Question: Brakes rubbing w/25s (now with pics)

[akelman]

I finally built the Peg today. For brakes, I went with alloy Chorus skeletons. I love the way they look, but the problem is that the front brake, which is dual-pivot, doesn't allow for enough clearance for 25 mm tires. Any suggestions? For example, are older alloy, non-skeleton Chorus or Record brakes somewhat lower profile? To be clear, the issue is that the tire is too tall to clear the brake at the highest (tire) and lowest (brake) point.

http://i45.photobucket.com/albums/f99/akelman/DSC_0102.jpg

http://i45.photobucket.com/albums/f99/akelman/DSC_0113.jpg

http://i45.photobucket.com/albums/f99/akelman/DSC_0108.jpg

http://i45.photobucket.com/albums/f99/akelman/DSC_0111.jpg

http://i45.photobucket.com/albums/f99/akelman/DSC_0112.jpg

http://i45.photobucket.com/albums/f99/akelman/DSC_0109.jpg

[AngryScientist]

I finally built the Peg today. For brakes, I went with alloy Chorus skeletons. I love the way they look, but the problem is that the front brake, which is dual-pivot, doesn't allow for enough clearance for 25 mm tires. Any suggestions? For example, are older alloy, non-skeleton Chorus or Record brakes somewhat lower profile? To be clear, the issue is that the tire is too tall to clear the brake at the highest (tire) and lowest (brake) point.

thats going to be more a function of the fork than the brakes. I'm running 25c tires and campy skeleton brakes with plenty of clearance left.

are the pads at basically the top of their adjustment travel in the calipers themselves?

[palincss]

You'll get more "overhead" clearance with the Paul Racer M centerpull, I think.

http://www.paulcomp.com/images/racermd2thumb.png

http://www.paulcomp.com/racerm.html

[kohlboto]

What fork are you running on the Peg?
Maybe this is your opportunity to pick up a Falz from Dario...

[akelman]

thats going to be more a function of the fork than the brakes

Yeah, I know, but I'm not sure what else to do other than try some pre-skeleton Campy brakes.

are the pads at basically the top of their adjustment travel in the calipers themselves?

Yup. Again, my hope is that perhaps pre-skeleton, or maybe a single-pivot front brake, will have a lower profile. It certainly looks like the rear skeleton brake, which is dual- rather than single-pivot has lots more room.

[akelman]

What fork are you running on the Peg?
Maybe this is your opportunity to pick up a Falz from Dario...

It's the steel fork that came with the bike. Honestly, I'm surprised that I'm having this problem, as it's a steel, box-crown fork that has ample room for 25s. The issue is just the brake/tire interface.

[akelman]

You'll get more "overhead" clearance with the Paul Racer M centerpull, I think.[/url]

Hmm, if I were certain that you were right, I might give it a try. But even then, I'm really comfortable with Campy brakes and prefer to stick with what I know.

[jmeloy]

It's the steel fork that came with the bike. Honestly, I'm surprised that I'm having this problem, as it's a steel, box-crown fork that has ample room for 25s. The issue is just the brake/tire interface.
Similar experience....

[echelon_john]

Hey Ari,
Different brakes have different clearances. You can buy 2-4 millimeters, generally speaking, with a single pivot over modern dual pivot. Don't know the aesthetic you're going for, but if I were you I'd try some Dura Ace single pivots.

JC

[oliver1850]

I have some older Chorus if you want to try them, or we can try to measure from the mount bolt to the inside of the arch to see if there's any difference. I don't have any skeletons to measure.

[akelman]

I have some older Chorus if you want to try them, or we can try to measure from the mount bolt to the inside of the arch to see if there's any difference. I don't have any skeletons to measure.

I'd love to know that measurement. With the skeletons, that number seems to be ~1cm.

[hokoman]

Try swapping the back to test fit to see if the single pivot works better for the front.

[zmudshark]

I just went out into the dark, crowded garage, and it appears that with dual pivot Chorus not much is gained. Dual pivot Centaur, on the other hand, may give you enough. I will measure tomorrow when the bikes are not hanging above the cars. I don't have any single pivots to check.

[bobswire]

Did you try before attaching cable? If so it'll rub, once cable is attached it allows proper clearance. Just thought I'd ask.

[akelman]

Did you try before attaching cable? If so it'll rub, once cable is attached it allows proper clearance. Just thought I'd ask.

Yeah, thanks. With the brake cable properly tensioned, the bottom of the caliper still rubs the top of the tire. Well, strictly speaking, it doesn't rub until the front wheel is weighted. Otherwise there's a teeny-tiny bit of clearance with 25 mm Vittoria Corsas mounted on A23s. There's no clearance at all with 25 mm PR3s mounted on Open Pros.

[choke]

Single pivots should have a bit more room than doubles.

It's the steel fork that came with the bike. Honestly, I'm surprised that I'm having this problem, as it's a steel, box-crown fork that has ample room for 25s. The issue is just the brake/tire interface.That really surprises me as my Peg steel fork with Deltas will easily clear 28s.

[oliver1850]

On a 9 speed era Chorus, I get something like 8mm from center of mount bolt to the point where the tire would hit. An older monoplaner is about the same.

[akelman]

On a 9 speed era Chorus, I get something like 8mm from center of mount bolt to the point where the tire would hit. An older monoplaner is about the same.

Those 2 mms would probably make all the difference. The other options, obviously, is to mount 23 mm tires up front.

[akelman]

Single pivots should have a bit more room than doubles.

Yup, I think if I can find some single-pivot Chorus or Record brakes, I'll be in good shape -- or, again, I can just run a 23 mm tire up front.

That really surprises me as my Peg steel fork with Deltas will easily clear 28s.

Well, I think the Deltas have more clearance than Chorus skeletons of recent vintage. And as I said above, the fork isn't the issue. It has plenty of room for 25s or even 28s.

[fourflys]

strange, I has ProRace 2 tire in 25mm (really measure out to about 27mm) on my Litespeed with Chorus 11sp skeleton brakes and never had an issue... I wonder if the mounting hole for the brake was just drilled too low?

any way to try the brake on another fork and see if it makes a difference?

[Louis]

And as I said above, the fork isn't the issue. It has plenty of room for 25s or even 28s.

Ari, it may still be a fork issue. (or a fork + caliper issue, they may both be partially responsible, depending on various compatibility dimensions)

How much space is there from the bottom of brake attach hole to the bottom of the fork arch? If it's a very short distance (compared, to say, all your other forks) then that may be putting the calipers too close to the tire.

[choke]

Well, I think the Deltas have more clearance than Chorus skeletons of recent vintage. And as I said above, the fork isn't the issue. It has plenty of room for 25s or even 28s.It had Chorus skeletons previously and they had more room.

[mvrider]

I have a 2010 Respo with the Trigon carbon fork, Chorus11 dual pivot in the front with Michelin Pro2 Race 25-mm... Lots of room, maybe 4-mm between the tire and the arms of the brake just below the mounting bolt. The brake pads are almost exactly centered in their mounting slot.

[oldpotatoe]

I finally built the Peg today. For brakes, I went with alloy Chorus skeletons. I love the way they look, but the problem is that the front brake, which is dual-pivot, doesn't allow for enough clearance for 25 mm tires. Any suggestions? For example, are older alloy, non-skeleton Chorus or Record brakes somewhat lower profile? To be clear, the issue is that the tire is too tall to clear the brake at the highest (tire) and lowest (brake) point.

Fork crown issue, not really brake issue.

[thwart]

Pegoretti with Reynolds Ouzo Pro, last gen Record brakes (pads 2/3 the way up the slot), Hed C2's, Mich PR3 25 mm tire.

... and lousy low light garage pic.

[Bob Loblaw]

I'd like to see a picture. If the fork can actually clear a 28c tire yet the brake rubs on a 25, it would seem there's an alignment problem. Maybe the brake mounting holes are off center, or the brake or the fork itself may be bent?

Well, I think the Deltas have more clearance than Chorus skeletons of recent vintage. And as I said above, the fork isn't the issue. It has plenty of room for 25s or even 28s.

[Germany_chris]

I have non-skeleton Veloce brakes and they clear my 22 tubulars and fenders with an Ouzo Pro.

[JayBay]

I have the same issue - A23 rims, Record skeleton dual-pivot calipers and an Easton EC90SL fork and there's no room for 25's :(

It seems like the brake mounting hole is just too close to the tire in this case.

[Doug Fattic]

As a framebuilder/painter, my bet is that the fork was made slightly short. I see all kinds of imperfectly made things when frames come in for refinishing – even those with big names. Measure from the center of the braking surface of the rim to the center of the brake hole. A Campy brake has 40 to 50 mm of clearance (Shimano's and others are 39 to 49). That means that if the brakes shoes are at the top of the slot, there is 40 mm from the center of the brake shoe to the bolt that attaches to the frame. And of course if they are at the very bottom of the slot the distance will be 50mm.

Typically a builder will make the fork length so the brake shoes will be in the middle of the slot for looks. That means your rim to hole distance should be 44 or 45mm. If it is less than that, than there is your problem. Sometimes builders will make the fork length long enough so that the shoes are at the bottom of the slot so larger tires can be used. That philosophy makes the most sense to me.

If the frame is made properly, it will position the shoes on both the front and rear brakes to be in the same position – either both will be in the middle of the slot or at the end. If they are different, than he was more careless than the best builders.

On occasion, a builder may position the brake shoe at the top of the slot to reduce the down tube length which will theoretically stiffen the frame. Mostly that just condemns the bicycle to use only very narrow tires.

[fatallightning]

I have the same issue - A23 rims, Record skeleton dual-pivot calipers and an Easton EC90SL fork and there's no room for 25's :(

It seems like the brake mounting hole is just too close to the tire in this case.

My EC70 fork wouldn't clear 25 tubulars, the brakes themselves did (skeleton DP). I have to go look, but I think my skeletons have more room then my Athena monos.

[Grant McLean]

As a framebuilder/painter, my bet is that the fork was made slightly short. I see all kinds of imperfectly made things when frames come in for refinishing – even those with big names. Measure from the center of the braking surface of the rim to the center of the brake hole. A Campy brake has 40 to 50 mm of clearance (Shimano's and others are 39 to 49). .

It sure sounds like the legs are too short, if that's the case, it will change the
geometry of the frame, considering the fact it's very unlikely the head tube
was designed on purpose to be lower to the ground with a shorter fork.

Most carbon forks are about 367mm to 370mm from tip to crown. 5 to 7 mm's
shorter than that, and i'd expect to be able to feel a change in handling.

-g

[akelman]

Just so everyone is clear, as I noted way upthread, I'm NOT talking about a carbon fork. It's the original steel fork that came with the bike that, when I use a double-pivot Campy skeleton brake, doesn't play nicely with a 25 mm tire. Still, it's not the end of the world. Even with the current brake drilling, the fork can comfortably accommodate 23 mm tires. Which is to say, suggesting that the blades are too short or the builder made a mistake seems off base.

I mention all of this because it's starting to feel like people are are calling into question Dario Pegoretti's frame building skills. Which, hey, if Grant and Doug want to do that, okay. I'm really not going to say that they're wrong, as I don't build bikes for a living. But my sense is that Dario (we're BFFs, which is why I use his first name) knew what he was doing when he built the Luigino and probably thought that 23 mm tires were just fine.

Thanks again, everyone.

[Grant McLean]

Just so everyone is clear, as I noted way upthread, I'm NOT talking about a carbon fork.

Pegoretti frames, like all production bikes are not made at the same time as the fork.
Your frame wasn't designed with a specific fork material in mind, it was created on
a jig with a particular fork span specification.

You should realize that frames are designed for a specific length fork,
regardless of material.

But the reality is - forks come in different lengths. The amount of variation
can be significant, and as I was trying to say in my previous post, combining
a difference of more than just 2 or 3 mm's will have a perceivable change
in the geometry.

If the fork you have is shorter, (which as Doug pointed out, likely) this would
explain the brake clearance issue. The reason I mentioned the carbon fork
length is because that is generally the fork span that most frames are
designed around in terms of a production standard. Since a steel fork is
made by hand, it can be cut to any number the builder makes it.
(intentionally or mistakenly)

-g

[akelman]

Pegoretti frames, like all production bikes are not made at the same time as the fork.
Your frame wasn't designed with a specific fork material in mind, it was created on
a jig with a particular fork span specification.

You should realize that frames are designed for a specific length fork,
regardless of material.

But the reality is - forks come in different lengths. The amount of variation
can be significant, and as I was trying to say in my previous post, combining
a difference of more than just 2 or 3 mm's will have a perceivable change
in the geometry.

If the fork you have is shorter, (which as Doug pointed out, likely) this would
explain the brake clearance issue. The reason I mentioned the carbon fork
length is because that is generally the fork span that most frames are
designed around in terms of a production standard. Since a steel fork is
made by hand, it can be cut to any number the builder makes it.
(intentionally or mistakenly)

-g

Okay, now I'm seriously confused, Grant. Let me explain why. Let's say that, for science, I pulled the fork from the frame and then mounted a double-pivot brake and a wheel with 25 mm tires on there. It would still rub. Which is to say, I'm not sure how or why you and Doug are extrapolating from the data at hand to suggest that the fork's blades are too short for the frame. Again, as noted above, the fork is original to the frame. It was, I believe, made by Dario for this frame. Is it possible that it was made at another time, painted to match, and then mated to this frame? Sure. Is it also possible that it's too small for this frame and thus might, as you've said, change the intended geometry? Sure. But isn't it considerably more likely that Dario drilled the fork to accommodate 23 mm tires rather than 25s? I'm genuinely not being intentionally obtuse -- I was born this way -- or trying to pick a fight. I just don't understand what led either you or Doug to begin talking about this being the wrong fork for this frame when there seems to be a simpler explanation.

[Grant McLean]

Okay, now I'm seriously confused, Grant. Let me explain why. Let's say that, for science, I pulled the fork from the frame and then mounted a double-pivot brake and a wheel with 25 mm tires on there. It would still rub. Which is to say, I'm not sure how or why you and Doug are extrapolating from the data at hand to suggest that the fork's blades are too short for the frame.

The reason why I think the fork is a little short is based on the belief that
there should be more room under the crown than there is.



Again, as noted above, the fork is original to the frame. It was, I believe, made by Dario for this frame. Is it possible that it was made at another time, painted to match, and then mated to this frame? Sure. Is it also possible that it's too small for this frame and thus might, as you've said, change the intended geometry? Sure.

"original" or not, forks are physically different lengths. They can range from
380 to 360mm. The main question is "what length makes the top tube level?"
Can you not see that the span of the fork needs to be a specific length in
order to hold the frame in the intended position?




But isn't it considerably more likely that Dario drilled the fork to accommodate 23 mm tires rather than 25s? I'm genuinely not being intentionally obtuse -- I was born this way -- or trying to pick a fight. I just don't understand what led either you or Doug to begin talking about this being the wrong fork for this frame when there seems to be a simpler explanation.

No, i don't think it's possible to drill the hole in the wrong place. I think
it's possbile the blades are a little too short.

Does it matter? Likely not if you didn't have the tire clearance issue, we'd
never be having this conversation.

-g

[akelman]

The reason why I think the fork is a little short is based on the belief that there should be more room under the crown than there is.

There's more room, though not much more room, between the top of the tire on this bike and the fork crown than there is from the top of the tire on my Ottrott and the fork crown in that case. In the latter case, the bike has an F2 fork and can accommodate 25 mm tires between the brake and the tire (though it's somewhat tight).

"original" or not, forks are physically different lengths. They can range from 380 to 360mm. The main question is "what length makes the top tube level?"

The top tube is level. Or it certainly appears that way. And yes, I know forks can be different lengths.

Can you not see that the span of the fork needs to be a specific length in order to hold the frame in the intended position?

Yes, I can see that. But again, isn't it more likely that Dario drilled the fork to be used with either single-pivot brakes, 23 mm tires, or both?

Seriously, am I missing something? That's entirely possible. But at this point, I'm not clear at all on what leads you and Doug to suggest that the fork is too short for the bike. Is there a way that I can figure this out? Should I measure the legs? Or are you guys just speculating?

No, i don't think it's possible to drill the hole in the wrong place. I think it's possbile the blades are a little too short.

Does it matter? Likely not if you didn't have the tire clearance issue, we'd
never be having this conversation.

-g

I don't think, possible or not, that Dario drilled the whole in the wrong place; I think he drilled it where he wanted it, so that the fork could accommodate 23 mm tires. That said, I still wonder why you think it's more likely that the blades are too short than that Dario thought 23 mm tires would be sufficient for a race bike. Finally, it only matters insofar as I was trying to figure out a solution to a problem, which is that I prefer to run 25 mm tires on my bikes. Fortunately, several people suggested something doable: running a single-pivot brake up front. But now, based on what you and Doug have said, I'm wondering if the fork isn't appropriate for this frame. If you've got more insight into that, or you have some way for me to figure this out definitely, I'd be grateful.

[Grant McLean]

Is there a way that I can figure this out? Should I measure the legs? Or are you guys just speculating?




Post a photo, one of the builders will respond.
Measure the length... but it has to be accurate.
Checking the top tube for level is difficult. If the fork is "too short"
it's likely only by 5mm or so, that would take a very accurate measurement
to make.

Accurately comparing fork crowns visually is difficult based only the clearances.
The difference between some carbon crowns and steel is that many carbon
forks have a great deal more height between the bottom and the top
than steel crowns, which can be quite shallow.

-g

[Doug Fattic]

It isn't uncommon for small inconsistencies to creep into a handmade frame. Most investment cast fork crowns already have pre-placed brake holes so it is unlikely that he drilled the hole closer to the bottom of the crown than the center. It is very easy - when a builder is whacking off the extra length of the fork blades before they are brazed into the crown - to get them bit short when he is evening up the cuts so they are the same length.

The question isn't whether the fork is too short for 25mm tires. It is too short or the tire wouldn't rub. The question becomes whether that short length was intentional or not. As I mentioned a builder can have the philosophy to put the brake shoes at the top of the slot thereby lengthening the head tube and shortening the down tube. The advantage is supposed to be a stiffer frame. The disadvantage is the ability to only use narrow tires. I don't use a short fork length because the customer could get annoyed when he wants to use a slightly wider tire and it hits the brake. Italian bikes tend to be all about speed so that placement could have been part of his design philosophy.

A careful builder will make the length of the front fork and the distance to the hole in the rear brake bridge so that the brake shoes in the slots on will be in the same place on both frames. (As an aside it doesn't mean the length from the axle to the hole will be the same front and rear because the rim is rising up from the crown in front and down in the rear). So if he is a top notch builder you can just look and see if the shoes in the slots are in the same place if using the brakes that were intended to be used on the frame. If they are not then he wasn't as careful as the best builders and he cut the blades too short.

Another check like Grant says is to see if you have an absolutely level top tube (if it was designed to have a level top tube). This is hard to tell unless you have a spirit level to assist you. Sometimes a top tube can be slightly sloped so less head tube is sticking up beyond the lug or it can be the "compact" style of a more sloping top tube. My 1972 Gran Criterium Masi (made for me) has a top tube that slops unintentionally 6mm. It is builder error. It doesn't matter much but neither was it made as carefully as it could have been.

[akelman]

Thanks, Doug and Grant. I'll post some pics in a few minutes if I can.

[EricEstlund]

Sounds like the legs are short for a 25. This is only a mistake if the frame was designed for a 25- if it was designed for a 23 then it's a non issue on that front.

Slightly older shimano brakes are slightly more roomy under the brake arch then their Campy brethren. Single pivots will be taller but generally narrower (though it doesn't sound like width or fender clearance are a concern).

While it might not buy you enough height, spacing the caliper slightly forward will move it to a different part of the tires arc, and may give you the room for a 25.

http://www.bicyclebuysell.com/images/2012/02/1328984715.jpg

[akelman]

Lots of pics. The relevant ones are at the bottom. I can take more later if you want to see something specific. Again, though, I can run a 25 on the back without any problem. Up front, you can see how tight it is below.

http://i45.photobucket.com/albums/f99/akelman/DSC_0102.jpg

http://i45.photobucket.com/albums/f99/akelman/DSC_0113.jpg

http://i45.photobucket.com/albums/f99/akelman/DSC_0108.jpg

http://i45.photobucket.com/albums/f99/akelman/DSC_0111.jpg

http://i45.photobucket.com/albums/f99/akelman/DSC_0112.jpg

http://i45.photobucket.com/albums/f99/akelman/DSC_0109.jpg

[Louis]

The bolt hole doesn't look that low on the crown.

I bet it's the brake that hangs lower than most.

[christian]

Nonsense. The fork legs are short, simple as that. Look at where the pads are on the brake arms. That's the way the fork was built.

[Grant McLean]

Lots of pics. The relevant ones are at the bottom. I can take more later if you want to see something specific. Again, though, I can run a 25 on the back without any problem. Up front, you can see how tight it is below.

Nice bike!

From the look of the brake slots, it's a few mm's shorter than i'd imagine
would be perfect. In terms of function, I don't see it being any issue other
than it being a tire clearance problem. My guess is 25mm tires wasn't
something that was planned on. A bit of a shame.

Two potential work-arounds if you're game:
Since the tallest part of the tire is a radial line from the hub,
(which winds up pretty much directly under the brake, it may make
a little bit of difference to space the front brake forward a little bit
by putting a few mm's of washer between the fork and brake.

Also, there is no reason you need to have the hub completely buried
in the drop out tips. You can most likely "lift" the hub out the the tips
by 2 mm's that could buy you some real estate under the front brake.

-g

[Louis]

Another idea - if you can get the brake arms to move closer in to the rim (the parts that hold the pads) that will allow the upper arm to move up and farther away from the tire.

I can think of a few ways to do that, none of them terribly attractive. 1) Shaving down the pads, 2) Removing the conical washer between the pad holders and the arms.

[Louis]

Nonsense. The fork legs are short, simple as that. Look at where the pads are on the brake arms. That's the way the fork was built.

But the tire clears the crown by a mile. So the legs can't be that short.

[echelon_john]

One other factor to consider is that you're running slightly wider rims. With those brakes, that effectively forces the outer pivot down closer to the tire when you open the brakes up to clear the wider rim.

I'm still of the opinion that a single pivot brake will buy you back plenty of room for a 25mm tire if that's your priority.

I agree with the other posters that, upon seeing where the pads are in the brake, the fork legs may have been cut a little short. Normally the builder would want them in the middle, unless the bike was specifically designed to max tire clearance, then the brake pad would be closer to the bottom of the slot.

[slowgoing]

Where does the frame builder measure from to decide where to put the brake bolt hole? Is it from the dropouts up, or from the fork crown down?

[Doug Fattic]

From your picture, it looks like the back brake also has the brake shoes at the top of the slot so it would appear that was his intention to design the frame that way. There is less brake flex that way. The reason that the front brake hits the tire and the back one does not is because the rim arch is higher in front and lower in back (your picture of your tire near your fork crown illustrates this).

This is a good example frame design choices. Maximizing one aspect can minimize something else. Frame design is always a series of compromises. As you gain advantage by doing one thing you lose something else (in this case tire clearance).

[Grant McLean]

But the tire clears the crown by a mile. So the legs can't be that short.

On a steel fork, it's not an issue of crown clearance, the brake arch
is going to be closer to the tire than the bottom of the crown.

There is lots of "capacity" to leave room for a bigger tire and a
campagnolo brake. The legs just need to be long enough.
The Peg apparently wasn't made with this in mind.
Just like Doug said - it's about choices.

this is the same brake and crown:

-g

[e-RICHIE]

this is the same brake and crown:

-g

Gee - these are not the same crown atmo. Craig is using my Richie-Issimo part
and the hole appears to be even lower than the as-cast version) and the Peg has
a Hitachi casting that was marketed under at least six different labels. These were
not sold drilled - that was a maker's mark to hit.

[jds108]

I think somebody in the other thread suggested trying your back brake (single pivot) in the fork, just to see if the single pivot clearance was better. Did you try that?

[Vientomas]

Upside-down brake drop bolt?

http://harmonywaterrestoration.com/drop%20bolt_pg.html

[Grant McLean]

the Peg has
a Hitachi casting that was marketed under at least six different labels..

Sorry, thought for sure it was an issimo crown on the Peg.
The have the same dimensions except for socket width, yes?

Anyway, the point of the photo was to show that it's possible to make
lots of clearance with a dual pivot brake and a 25mm tire.
( but at the risk of beating this issue to death already )
The Peg looks to be intended for 23mm tires.

-g

[hokoman]

Upside-down brake drop bolt?

http://harmonywaterrestoration.com/drop%20bolt_pg.html

wow - that's as much as new brakes that might work!

[Vientomas]

wow - that's as much as new brakes that might work!

Agreed. I used the image to illustrate what a "drop bolt" is. I suspect there are more reasonable alternatives to this manufacturer.

[Doug Fattic]

Where does the frame builder measure from to decide where to put the brake bolt hole? Is it from the dropouts up, or from the fork crown down?
A framebuilder determines the length of the fork from the axle up if he is using brake clearance (determined by where the brake shoe will be in the slot of a chosen brake) and from the crown down if he is using fender clearance as his reference. Once he has established his chosen distance, he can determine how much of each end of the fork blades he has to cut off. Usually this is done after brazing in the front dropouts and raking the blades. Almost all fork crowns already have a hole where the hole will be drilled. It is the builder's reference point when measuring how much blade should be cut off (if using the brake clearance model).

[akelman]

From your picture, it looks like the back brake also has the brake shoes at the top of the slot so it would appear that was his intention to design the frame that way. There is less brake flex that way. The reason that the front brake hits the tire and the back one does not is because the rim arch is higher in front and lower in back (your picture of your tire near your fork crown illustrates this).

This is a good example frame design choices. Maximizing one aspect can minimize something else. Frame design is always a series of compromises. As you gain advantage by doing one thing you lose something else (in this case tire clearance).

This is, I believe, absolutely right, Doug (if I may). Dario (again, my BFF) designed this bike for 23 mm tires or narrower. The workaround, as others have suggested, is probably to use a single-pivot brake up front, as I have no issues with the single-pivot brake in the rear clearing a 25.

In the end, then, I think the fork legs are, as I guessed (and hoped) the right length for this bike. It's just that they're not the right length for a guy (me), who wants to run 25 mm tires *and* a double-pivot front brake.

Thanks, everyone, for all of your input.

[dave thompson]

As others have suggested, on your front brake use a spacer of 2~3mm thick which will move the caliper up as well as out. You may have to use a longer brake nut, which is easy to find, and as long as the nut can grab about 5 threads of the brake bolt, you're golden.

[akelman]

As others have suggested, on your front brake use a spacer of 2~3mm thick which will move the caliper up as well as out. You may have to use a longer brake nut, which is easy to find, and as long as the nut can grab about 5 threads of the brake bolt, you're golden.

Looking at the bike, I'm not seeing how this will work. But I'm absolutely going to try it as soon as I get home. And there's no doubt that I have plenty of brake nut to play nicely with a spacer.

[Peter P.]

Alright; I'm gonna make a "whack job" suggestion.

From the photos, it looks like this is doable:

Is there any reason the front brake mounting hole can't be filed or machined oval a couple millimeters to shift the brake arch up and provide the clearance needed? I imagine any competent framebuilder with a drill press would be able to accomplish this without disturbing the paint.

I realize this might be considered butcher-work or sacrilege, but it seems a reasonable workaround that would be all but invisible.

I also imagine some other brand dual-pivot brakes might mate better. I'm sure some would think breaking up the Campy group would be heresy, but I'm just trying to think of viable solutions.

Comments?

[Louis]

Comments?

1) Way easier to try a different caliper (or tire, which is what I would do)

2) A slot might allow vertical motion as forces are applied to the brake bolt during braking. You never want to rely on friction to carry loads. Let the bolt and nut bear up against the hole, as they were designed to do.

Edit: Let me rephrase that - If you can avoid it, you would rather not depend on friction in an important load path. It happens all the time on bikes, but that doesn't mean that it's a good idea. IMO the most egregious example of this is brake cable pinch bolts.

[buldogge]

If you wanted to get crazy with it, you would drill the holes oversize and use a bushing(s) with an offset hole.

I would just use the double rear caliper action, or run a 25/23 combo.

-Mark in St. Louis

[cnighbor1]

Perhaps try another brand of tire. Might have a lower profile
Or go to a fatter brand tire in 23c
But has shown you need to try another brake. Just try something you have on hand
charles

[velomateo]

The Vittoria Pave' CG's are 24mm, and I think they come in all black too. Might be enough to get your clearance issue solved without going to a 23mm tire. And they ride like butter.

[cnighbor1]

If you could get a cresent shape wedge at top of drop outs it would lower axle and of course wheel
Quick releases would hold every thing in place
Till you take wheel out
I have had with pads at bottom brake just below top of rim Not a nice thing to ride width
That is why my wacko idea came from to lower wheel

[rwsaunders]

You could always send an email to Caldonazza...

http://www.pegoretticicli.com/contact

[Chance]

Another idea - if you can get the brake arms to move closer in to the rim (the parts that hold the pads) that will allow the upper arm to move up and farther away from the tire.

I can think of a few ways to do that, none of them terribly attractive. 1) Shaving down the pads, 2) Removing the conical washer between the pad holders and the arms.

Valid point. As he mentioned having tried in a previous post, using narrower Open Pros instead of A23s will also allow the caliper to be adjusted in a more closed position that should move that arm more out of the way of the tire.

http://i45.photobucket.com/albums/f99/akelman/DSC_0112.jpg


Also, if more stopping power is needed beyond what a single pivot caliper can provide, a brake like a Zero Gravity or similar may provide more clearance and maintain adequate stopping power.

[choke]

Since we're throwing out crazy ideas.....

You could always take a dremel to the arm and grind away until you're happy with the clearance.

[StephenCL]

A campy delta caliper was mounted with a bolt that could be adjusted up or down about 10mm if I remember correclty. This allowed you to adjust the complete caliper up or down relative to the bolt hole.

I would be trying this as my solution....

FYI, I have seen this issue before....Grant is right, the fork legs are not long enough to accomodate a 25mm. Either by design, or by screw up....

Warm regards,

Stephen

[Louis]

Let's assume for the sake of argument that a 23 tire will fit.

In a blind taste-test do you think you would (a) notice an appreciable difference, and (b) prefer the 25 over the 23? I doubt I would.

If the 23 fits you must acquit.

[dave thompson]

Louis, all things considered equal, you could feel the difference between a 23 and 25MM tire.

[kceb_cire]

I didn't read the rest of this thread, 5 pages is too long.
But... I know that my shimano dual pivot brakes give me more clearance than campagnolo centaur calipers. Same wheel, same tire, same bike.

[Louis]

Louis, all things considered equal, you could feel the difference between a 23 and 25MM tire.

Dave, perhaps, I don't know. For example, I can't tell the difference between Michelin Pro Race 3s and Conti GP 4000s. Other folks say they can tell. To be honest I'm a bit skeptical of that sort of statement, but don't deny that it may be true.

[choke]

I was curious regarding fitment so I tried a few different calipers on the back of one bike that has minimal clearance with a Ruffy Tuffy on a Neutron. The results were as follows;

Chorus skeleton single pivot: It clears but doesn't have a lot of room when the brake is applied. The arms move downward and because of the shape get very close to hitting the tire.

Chorus monoplaner: More room than the skeleton but the arms also get close to the tire. In either case you could probably shim the pads out a bit and have enough room to be comfortable, though if I was doing that I'd likely choose the monoplaners as they don't get quite as close to the tire.

CdA Delta: Clears with bit less room than the two Chorus models but because of the design there's no problem with the brake arms getting close.

Record Delta: Won't fit at all - the body hits the tire long before the pads are low enough to contact the rim.


A campy delta caliper was mounted with a bolt that could be adjusted up or down about 10mm if I remember correclty. This allowed you to adjust the complete caliper up or down relative to the bolt hole.The Record Delta does adjust that way, and I just measured one and it's closer to 15mm so your memory is pretty good. The problem with them is that they don't have much pad adjustment so the body has to be placed fairly close to the tire for the pads to contact the rim. The Croce d'Aune Deltas don't have the adjustable body and offer more adjustment at the pads and thus more clearance.

[rwsaunders]

Louis, all things considered equal, you could feel the difference between a 23 and 25MM tire.

I would have disagreed with Dave until a month ago, when I replaced 23's with 25's on my Legend. Night and day difference with the same model tires and wheels; Conti Gran Prix 4 Seasons tires on DA/Open Pro wheels. Fwiw, the 25's fit on an F1 fork too.

[jmeloy]

This is, I believe, absolutely right, Doug (if I may). Dario (again, my BFF) designed this bike for 23 mm tires or narrower. The workaround, as others have suggested, is probably to use a single-pivot brake up front, as I have no issues with the single-pivot brake in the rear clearing a 25.

In the end, then, I think the fork legs are, as I guessed (and hoped) the right length for this bike. It's just that they're not the right length for a guy (me), who wants to run 25 mm tires *and* a double-pivot front brake.

Thanks, everyone, for all of your input.
Gang, had the same issue with the same tire on my Marcelo but on the rear brake. I wrote Dario for advice and he kindly replied "it is a race bike designed for 23s... switch and you will have no issue, my friend".

[mister]

Gang, had the same issue with the same tire on my Marcelo but on the rear brake. I wrote Dario for advice and he kindly replied "it is a race bike designed for 23s... switch and you will have no issue, my friend".

lol.
i just read the first page and skipped to the last to say...the fork is made short on purpose.
shorter blades make a stiffer fork.
notice the pads all way up in the slots...any brake on the front is going to have problems clearing a 25mm tire

just run a quality 23mm tire and enjoy the bike

[akelman]

the fork is made short on purpose.
shorter blades make a stiffer fork.
notice the pads all way up in the slots...any brake on the front is going to have problems clearing a 25mm tire

Just so. That said, it clears a 25 now (as seen in the pics), albeit barely. And I'm reasonably confident that a single-pivot in the front will provide ample clearance for a 25. I'll update this thread when I try it -- perhaps as soon as Thursday. In the meantime, I've ridden it with a 25 mm tire, tight clearance be damned, and the bike is just fantastic.

[Grant McLean]

lol.
i just read the first page and skipped to the last to say...the fork is made short on purpose.
shorter blades make a stiffer fork.
notice the pads all way up in the slots...any brake on the front is going to have problems clearing a 25mm tire

just run a quality 23mm tire and enjoy the bike

Yeah, thanks for pointing out the obvious.
unfortunately the photos weren't added until the conversation
was already well underway. Apparently it's true a picture
is worth a thousand words!

-g

[bobswire]

Maybe running a wide rim like velocity a23 will allow you to use the 25's? Anyway it makes sense to me.

[Doug Fattic]

There is one more trick that you can try to provide a tiny bit more room under the brake and that is by playing with the centering adjustment screw. First you pivot the brake a bit to the side (probably turn it towards the non-drive side) by loosening and then retightening the recessed bolt on the back of the crown after the brake has been cocked over a little. Next use the very small screw that centers the brake to adjust it so the shoes are evenly spaced between the rim. This may create more space under the one arm that is closest to the tire. I'm not sure if this method will work on every dual pivot brake but I know it will on some. It looks like you need very little more room to keep the tire from rubbing. Try it and see.

[Fixed]

There is one more trick that you can try to provide a tiny bit more room under the brake and that is by playing with the centering adjustment screw. First you pivot the brake a bit to the side (probably turn it towards the non-drive side) by loosening and then retightening the recessed bolt on the back of the crown after the brake has been cocked over a little. Next use the very small screw that centers the brake to adjust it so the shoes are evenly spaced between the rim. This may create more space under the one arm that is closest to the tire. I'm not sure if this method will work on every dual pivot brake but I know it will on some. It looks like you need very little more room to keep the tire from rubbing. Try it and see.

i like this fix
cheers :banana:

[Germany_chris]

Let me be the first to say it..

isn't it kinda sad that we have to "tweak" brakes to make perfectly normal tires fit..

what possible benefit could those short arms have to a normal rider?

[jmeloy]

Just so. That said, it clears a 25 now (as seen in the pics), albeit barely. And I'm reasonably confident that a single-pivot in the front will provide ample clearance for a 25. I'll update this thread when I try it -- perhaps as soon as Thursday. In the meantime, I've ridden it with a 25 mm tire, tight clearance be damned, and the bike is just fantastic.

Rode mine (25's) for ~150 miles and no more rub and YEP she rides beautifully!

[akelman]

Let me be the first to say it..

isn't it kinda sad that we have to "tweak" brakes to make perfectly normal tires fit..

what possible benefit could those short arms have to a normal rider?

First, the fork isn't short. As I suggested when that first came up, the more likely explanation, it seemed to me, was that the builder thought 23s were sufficiently wide for a bike like this. Why that seemed less likely to some other people than builder error still isn't entirely clear to me*, but that's water under the bridge. Regardless, as it turns out, it's almost certainly the case that the builder intended that this bike should be run with tires that would max out at 23 mm.

Second, using 25s on a race bike is something I like to do. In fact, it's now something lots of people like to do. But a) it's a relatively recent phenomenon for that to be the case; and b) it's not entirely uncontroversial.

Third, and perhaps most important, I'm running 25s on there now. With a single-pivot brake in the rear, there's ample room back there for a 25. But even up front, a 25 will fit. It's just tighter under the brake than I'd like it to be. Still, I'm nearly certain that if I run a single-pivot brake up front, I'll be just fine.

Finally, if I wanted to be certain that a Luigino would run 25s, 28s, or even wider tires than that, I would have needed to commission a custom frame. That's just the way it is. Stock frames always have certain limitations baked into the cake. I expect that were Dario here, he would say that this frame is designed for going fast (comfortably), and that he didn't think that building in plenty of room for 25s was a good trade-off for a slightly more flexible fork. Which is just a long way of saying, again, if running wide tires was my highest priority, I should have gone custom or bought an off-the-rack frame designed for such a thing: a Hampsten Strada Bianca or something like that. But then I would have had to contend with other design limitations, including, of course, surrounding my choice of brakes.

* Being extra careful now: I'm still not trying to pick a fight about this issue. I think both Grant and Doug had their reasons for making the suggestion they made. My guess, based on what they said, is that such a thing -- builder error -- surely must happen frequently enough for it to have seemed likely in this case. Regardless, I appreciated their comments, even if they confused me slightly and briefly freaked me out.

[fourflys]

I'd sure like to know if any other Pegs have this issue... I have no doubt Dario could have built this bike with only 23's in mind but I'm pretty it would be the same with many other Pegs as well... at least this model of Peg anyway...

anyone else have this model?

[Germany_chris]

First, the fork isn't short. As I suggested when that first came up, the more likely explanation, it seemed to me, was that the builder thought 23s were sufficiently wide for a bike like this. Why that seemed less likely to some other people than builder error still isn't entirely clear to me*, but that's water under the bridge. Regardless, as it turns out, it's almost certainly the case that the builder intended that this bike should be run with tires that would max out at 23 mm.

Second, using 25s on a race bike is something I like to do. In fact, it's now something lots of people like to do. But a) it's a relatively recent phenomenon for that to be the case; and b) it's not entirely uncontroversial.

Third, and perhaps most important, I'm running 25s on there now. With a single-pivot brake in the rear, there's ample room back there for a 25. But even up front, a 25 will fit. It's just tighter under the brake than I'd like it to be. Still, I'm nearly certain that if I run a single-pivot brake up front, I'll be just fine.

Finally, if I wanted to be certain that a Luigino would run 25s, 28s, or even wider tires than that, I would have needed to commission a custom frame. That's just the way it is. Stock frames always have certain limitations baked into the cake. I expect that were Dario here, he would say that this frame is designed for going fast (comfortably), and that he didn't think that building in plenty of room for 25s was a good trade-off for a slightly more flexible fork. Which is just a long way of saying, again, if running wide tires was my highest priority, I should have gone custom or bought an off-the-rack frame designed for such a thing: a Hampsten Strada Bianca or something like that. But then I would have had to contend with other design limitations, including, of course, surrounding my choice of brakes.

* Being extra careful now: I'm still not trying to pick a fight about this issue. I think both Grant and Doug had their reasons for making the suggestion they made. My guess, based on what they said, is that such a thing -- builder error -- surely must happen frequently enough for it to have seemed likely in this case. Regardless, I appreciated their comments, even if they confused me slightly and briefly freaked me out.

Who's talking about the fork?? Are there arms on a fork?

I was talking about the brake arm..thats the offending part

I hope this picture illustrates what I'm talking about..I have 22mm Tubulars and fenders on an Ouzo Pro and there is room to spare

[soulspinner]

I like trying the Vittoria 24 mms. Great riding tire, prolly better than some 25s out there, prolly just enuff room..........

[mister]

Who's talking about the fork?? Are there arms on a fork?

I was talking about the brake arm..thats the offending part

I hope this picture illustrates what I'm talking about..I have 22mm Tubulars and fenders on an Ouzo Pro and there is room to spare

dude
forks come in a variety of lengths, measured from the axle to the fork crown race...
akelmans is short
yours is longer
the brakes have almost nothing to do with the problem
nobody is gonna go from having a mm of clearance with a 25mm tire to being to run 22mm tires and a fender just from a brake caliper swap...

[akelman]

I'd sure like to know if any other Pegs have this issue... I have no doubt Dario could have built this bike with only 23's in mind but I'm pretty it would be the same with many other Pegs as well... at least this model of Peg anyway...

anyone else have this model?

Check out jmeloy's comments in this thread. He's in the same boat, though his Peg isn't a Luigino.

[fourflys]

Check out jmeloy's comments in this thread. He's in the same boat, though his Peg isn't a Luigino.

ah, interesting... guess that may cross a Peg off my list then as I won't ride a tire smaller than a 25 anymore... I'll have to research pretty thoroughly if I decide to get a Peg at some point...

[Germany_chris]

dude
forks come in a variety of lengths, measured from the axle to the fork crown race...
akelmans is short
yours is longer
the brakes have almost nothing to do with the problem
nobody is gonna go from having a mm of clearance with a 25mm tire to being to run 22mm tires and a fender just from a brake caliper swap...

He will..he's got plenty of clearance on the fork itself..guy just wants to put 25's on..

[weaponsgrade]

fwiw, I had a first year luigino and was able to run pro race 25s and chorus dual pivots (preskeleton) on velocity aeroheads no problem.

[fourflys]

fwiw, I had a first year luigino and was able to run pro race 25s and chorus dual pivots (preskeleton) on velocity aeroheads no problem.

ProRace3 25's or ProRace2 25's? the reason I ask is the 2's are huge while the 3's are barely 25 on a good day I think... at least that was my experience with them...

BTW- a sad note, my last ProRace2 25 died today... :butt: such awesome tires that totally outshine the 3's or, from what I've heard, the new 4's...

[Doug Fattic]

I think there is a lesson here for those in the market for either a production or custom frame and that is what inspired me to comment in the first place. You want the brake clearance on your frame to match the widest tire you would commonly use. Check and see where the brake shoes are in the slot first before making the purchase or tell your builder the widest tire you might want to run and if fenders would ever be an option. Most racing brakes have a range from 39 to 49 mm or 40 to 50 if they are Campy. When Campy came out with their original sidepull brakeset in 1968 or so they were 47 to 57 mm. This was a reduction from the centerpulls most common before that. As racing bicycles became more specific to their purpose and roads in Europe improved, then brakes clearances could tighten up.

However I was surprised that Dario went to the max on this frame he made. It is certainly uncommon for a builder to make a frame designed so the brake shoes need to be at the top of the slot. However his frames are supposed to be max and one shouldn't expect a Maserati either to be comfort oriented.

Of the last 150 students that have taken my framebuilding class only 3 of them have chosen to use a 39 to 49mm brake – and then they made the clearance to be at the bottom of the slot in case they might want to use a 28. This is because they are mostly making practical bicycles and not primarily for speed (although they might want to get somewhere fast with their load).

[TMB]

I read this thread last night and was really quite puzzled as I have the same frame and run 25 or 27 tires routinely.

No problems at all.

I think the issue, honestly is the Skeleton brakes. Just not enough room.

These pics are today - Conti 25's

[echelon_john]

the 23mm rims are playing a role too. it would be interesting to see a pic of the same setup, adjusted for an open pro/19mm rim. i bet it would buy at least another 2-3mm of daylight.

[TMB]

More,

I did not adjust the brakes or anything, just threw the wheel in for the picture.

Vittoria 27 tubulars at 75 psi.

[TMB]

I think you have all the room you need or want with the fork, the issue is those silly Skeleton brakes.

[akelman]

I think you have all the room you need or want with the fork, the issue is those silly Skeleton brakes.

I suppose I should pull a non-skeleton caliper off another bike -- oddly, I only have skeletons in the shed -- and see if it works. That said, it might just be that your fork, which is the coolest thing in the history of cool, has slightly longer blades than mine.

[akelman]

Seriously, I could look at pictures of that fork all day. I'm smitten.

[akelman]

Equally seriously, I've now ridden this bike several times, and it's really making me happy. I could still use a 1 cm spacer under the stem, but that's nobody's fault but my own (and the previous owner, who cut the steerer).

[TMB]

I suppose I should pull a non-skeleton caliper off another bike -- oddly, I only have skeletons in the shed -- and see if it works. That said, it might just be that your fork, which is the coolest thing in the history of cool, has slightly longer blades than mine.

I would really be surprised if my blades were longer, I am fairly sure I have more pairs of these things.

I will scout around and find a set. If I do have some I will throw a pair in the mail so you can try them out.

[TMB]

Seriously, I could look at pictures of that fork all day. I'm smitten.

My bike is in the garage, blushing!

[akelman]

My bike is in the garage, blushing!

You keep that beauty in the garage? Tell her that if she lived here, she'd have a bedroom all to herself.

[John M]

That Peg is beautiful. Solve all of your problems and send the frame to Seattle. I'll happily ride it with 23s!

[akelman]

That Peg is beautiful. Solve all of your problems and send the frame to Seattle. I'll happily ride it with 23s!

TMB's is closer! And he makes it live outside!!! (Though, having seen pics of TMB's garage, I'd be pretty happy living there.)

[choke]

I'd sure like to know if any other Pegs have this issue... I have no doubt Dario could have built this bike with only 23's in mind but I'm pretty it would be the same with many other Pegs as well... at least this model of Peg anyway...FWIW my Responsorium will clear 28s with skeleton brakes front and rear.the 23mm rims are playing a role too. it would be interesting to see a pic of the same setup, adjusted for an open pro/19mm rim. i bet it would buy at least another 2-3mm of daylight.I have no experience with wider rims but it seems to me that the height of the tire would be a bit shorter since it's spread out more.

[akelman]

FWIW my Responsorium will clear 28s with skeleton brakes front and rear.

I wonder if: a) the Respo is designed to be more of an all-day bike and thus has more room for bigger tires; b) the Respo has a carbon fork, which Dario might have designed -- if you have one of the new ones -- but almost certainly didn't build, so it's not clear that the data point is relevant; and/or c) Dario makes his bikes by hand, and there's inevitably going to be some variability between them, and particularly between different models.

I have no experience with wider rims but it seems to me that the height of the tire would be a bit shorter since it's spread out more.

I think you're right. I had an 18 mm rim (Mavic OP) with a 25 mm Vittoria on there, and it was, if anything, tighter.

[TMB]

I wonder if: a) the Respo is designed to be more of an all-day bike and thus has more room for bigger tires; b) the Respo has a carbon fork, which Dario might have designed -- if you have one of the new ones -- but almost certainly didn't build, so it's not clear that the data point is relevant; and/or c) Dario makes his bikes by hand, and there's inevitably going to be some variability between them, and particularly between different models.



I think you're right. I had an 18 mm rim (Mavic OP) with a 25 mm Vittoria on there, and it was, if anything, tighter.


For reference, the two tires I posted shots of:

The Conti 25 is on a Neutron rim.

The Vittoria 27 is on a Nemesis rim.

[choke]

b) the Respo has a carbon fork, which Dario might have designed -- if you have one of the new ones -- but almost certainly didn't build, so it's not clear that the data point is relevant;Mine has his steel fork like yours.

c) Dario makes his bikes by hand, and there's inevitably going to be some variability between them, and particularly between different models.I'd say that this is the most likely answer and certainly a factor.

[akelman]

For those who care, I put a single-pivot skeleton on the front, and all's well. There's actually room for 28s now, though that's not how I roll. The next step is to try a set of Chorus Monoplaners. And if I can find a relatively cheap pair of non-skeleton Chorus dual-pivots, I may try those as well.

[Louis]

So the key is the distance from the attach bolt to the bottom of the caliper arch.

You learn something new every day.

Thanks for the education.

[akelman]

So the key is the distance from the attach bolt to the bottom of the caliper arch.

Exactly. The lingering question is whether TMB is right, and the culprit is these "silly" skeleton brakes. In other words, will a non-skeleton, dual-pivot brake have more clearance. Stay tuned!

[Charles M]

Go buy a set of EE...

They have adjustable height for the body of the brake it's self and will rotate up and clear the tire.

[khjr]

For those who care, I put a single-pivot skeleton on the front, and all's well. There's actually room for 28s now, though that's not how I roll. The next step is to try a set of Chorus Monoplaners. And if I can find a relatively cheap pair of non-skeleton Chorus dual-pivots, I may try those as well.

Regret that you received far more constructive criticism of your frame that you had solicited when your original question of "what caliper arms have more clearance under them than others," seemed pretty straightforward. I had a similar challenge with a too-tall Panaracer Pasela in a steel frame that I was building for my girlfriend. That squeeze was in the back, though, and caused by the brake bridge being a little low. In that case I found the Campagnolo 8 speed Mirage Monoplaners to have LESS clearance between the arm and tire than a dual pivot. The Tektro dual pivot that I tried next worked perfectly with way more clearance. Someone else suggested using an additional or thicker knurled washer, and I experimented to find that to yield more clearance than one might think as well (although it ultimately wasn't necessary with the Tektro).

[akelman]

Regret that you received far more constructive criticism of your frame that you had solicited when your original question of "what caliper arms have more clearance under them than others," seemed pretty straightforward. I had a similar challenge with a too-tall Panaracer Pasela in a steel frame that I was building for my girlfriend. That squeeze was in the back, though, and caused by the brake bridge being a little low. In that case I found the Campagnolo 8 speed Mirage Monoplaners to have LESS clearance between the arm and tire than a dual pivot. The Tektro dual pivot that I tried next worked perfectly with way more clearance. Someone else suggested using an additional or thicker knurled washer, and I experimented to find that to yield more clearance than one might think as well (although it ultimately wasn't necessary with the Tektro).

Eh, it all worked out in the end. And I think people were trying to be constructive throughout the discussion. Regardless, I remain curious to see if the Chorus Monoplaners that I have en route will work. They're very pretty brakes, and I'd love to run them. But if not, I'll try some more recent non-skeleton Chorus or Record dual-pivots. It just feels silly to have two rear brakes on the bike, and wasteful to have two double-pivot Chorus skeletons sitting in the shed.

[Fixed]

Exactly. The lingering question is whether TMB is right, and the culprit is these "silly" skeleton brakes. In other words, will a non-skeleton, dual-pivot brake have more clearance. Stay tuned!

great news enjoy
cheers :hello: