Brake clearance and wide rims

[tv_vt]

Switched out a pair of DT road rims (19mm wide) for a set of Hed Belgiums (23mm wide). I'm using Dura Ace 7700 brakes. While setting up the brakes for the wider rims, I noticed a lot of slack in the brake cable. And then noticed that the brake calipers just wouldn't open up past a certain point. There seems to be a maximum width of rim these calipers will take. With the narrower rims, I could have lots of lever pull to moderate the calipers. With the wider rim, I have very little lever pull to play with - they lock up pretty fast when I give them a squeeze.

Just wondering if this is an issue with most decent road brake calipers, or if newer ones may be more adapted to wider rims. Anyone notice this before?

I think it's more of a problem when the brake pads are new, too...

Thanks,

Thom

[Bruce K]

At the suggestion if a local mechanic I had to leave my Zero Gravitys open to accommodate the wider rims. There just wasn't enough clearance otherwise.

It was also suggested to use new pads as the angle of contact was different and there are different wear patterns (at least on the ZGs).

Try leaving the lever up (if Shimano or ZG) and see if that helps. You can also LIGHTLY sand the pads to get a little more clearance (but obviously less life)

BK

[oldpotatoe]

Switched out a pair of DT road rims (19mm wide) for a set of Hed Belgiums (23mm wide). I'm using Dura Ace 7700 brakes. While setting up the brakes for the wider rims, I noticed a lot of slack in the brake cable. And then noticed that the brake calipers just wouldn't open up past a certain point. There seems to be a maximum width of rim these calipers will take. With the narrower rims, I could have lots of lever pull to moderate the calipers. With the wider rim, I have very little lever pull to play with - they lock up pretty fast when I give them a squeeze.

Just wondering if this is an issue with most decent road brake calipers, or if newer ones may be more adapted to wider rims. Anyone notice this before?

I think it's more of a problem when the brake pads are new, too...

Thanks,

Thom

Not uncommon with the newer rims and a lot of brakes. The biggest problems I have seen is with some light weight, aftermarket brakes and some TT bikes with integrated into the frame and fork, brakes. Worked on a Boardman TT bike, gent had new Zipp rims and they wouldn't fit between the brakes even with the brake cable disconnected.

[Climb01742]

Worked on a Boardman TT bike, gent had new Zipp rims and they wouldn't fit between the brakes even with the brake cable disconnected.

how loudly did the customer scream when he saw this?:eek:

[Bruce K]

Some frame makers have had to widen the chain stays to accommodate the new wider rims

I bought a HED Jet disc with a PT Pro+ hub with only 20 miles on it at a VERY good price because it didn't fit the original buyers frame. Talk about someone who wanted to scream....

BK

[572cv]

TV,
My very limited experience in this arena is with Hed Ardennes C2, a sram group on one bike and ultegra on another.

- Ultegra 6600 brakes behave as you describe with a quick grab of the brakes that takes a bit of getting used to. They also BARELY accommodate a 25c tire, even fully open.

- Sram red brakes seem to have a wider full open position and a little more to work with on adjustment. It isn't much but is noticeable for the C2 rims. I am happier with this set up.

[atanz]

I've had to leave my 6700 and 7800 brake calipers in the open position to get decent modulation

[tv_vt]

Wow, didn't realize this problem was so widespread. Since the newer Shimano wheels are built with slightly wider rims (I think about 21-22mm wide), I thought maybe newer 6700/7900 brake calipers would work better, but sounds like this still needs some work.

My brake pads are pretty new (thick), so the lever modulation should improve a bit as the pads get thinner. Or I could file them down a hair, I suppose.

[tannhauser]

Switched out a pair of DT road rims (19mm wide) for a set of Hed Belgiums (23mm wide). I'm using Dura Ace 7700 brakes. While setting up the brakes for the wider rims, I noticed a lot of slack in the brake cable. And then noticed that the brake calipers just wouldn't open up past a certain point. There seems to be a maximum width of rim these calipers will take. With the narrower rims, I could have lots of lever pull to moderate the calipers. With the wider rim, I have very little lever pull to play with - they lock up pretty fast when I give them a squeeze.

Just wondering if this is an issue with most decent road brake calipers, or if newer ones may be more adapted to wider rims. Anyone notice this before?

I think it's more of a problem when the brake pads are new, too...

Thanks,

Thom

It's not a problem -- you can dial in more cable slackness so it actuates where you're used to or just rewire your brain to modulate with more finesse.

The brake lever is not a toggle switch.

[FlashUNC]

I've found my Campy calipers have plenty of clearance on Belgium rims and good feel, fwiw.

(Not that this is meant to start another group argument.)

[Chance]

It's not a problem -- you can dial in more cable slackness so it actuates where you're used to or just rewire your brain to modulate with more finesse.

The brake lever is not a toggle switch.

Sounds to me that he is saying the brake caliper won't open much past a 23-mm wide rim, and since it's not good practice to leave a brake cable loose (that is without tension from brake return spring) then the pads will contact the rim as soon as he starts to pull on lever. To me that would suck big time, particularly if the rider had smaller-than-normal hands.

As stated, it sounds like caliper won't open enough to set it to normal clearance between pads and rim.

[christian]

Worked on a Boardman TT bike, gent had new Zipp rims and they wouldn't fit between the brakes even with the brake cable disconnected.Wider rims make you faster, right up to the point where they make you a lot slower.

[tannhauser]

Sounds to me that he is saying the brake caliper won't open much past a 23-mm wide rim, and since it's not good practice to leave a brake cable loose (that is without tension from brake return spring) then the pads will contact the rim as soon as he starts to pull on lever. To me that would suck big time, particularly if the rider had smaller-than-normal hands.

As stated, it sounds like caliper won't open enough to set it to normal clearance between pads and rim.

I don't know that's it's bad practice to keep the cable "loose", but it's good to have a predictable engagement point. There is no absolute when it comes to cable tension -- it's personal preference. I've kept my loose, tight, in-between...it all works if I know what to expect.


If engagement is too "sudden" for the op the new, thick grabby pads on some clean rims could be the culprit.

I'm just trying to give the OP some possible solutions to his problem rather than having to rely on Shimano, Sram or Campy to engineer the solution, which I think is coming anyway.

Another issue is the rim's ability to take a tire that otherwise fits through the pad stop dead, which is somewhat irritating but can be solved by letting some air out.

That reminds me...off to clean my rims and brake pads.


Edit: done -- much better!

fwiw I have a Campy brake on HEDs -- no problem.

[tannhauser]

Just to clarify I have had trouble with too loose a cable with v-brakes, maybe has something to do with the pull ratio.

[Rueda Tropical]

Anyone use the Mavic SSC brakes with 23mm rims?

[FlashUNC]

Anyone use the Mavic SSC brakes with 23mm rims?

Mechanic I know uses SSC brakes with Hed Belgiums. No issues.

[thwart]

Campy Record brakes with salmon Koolstops and Hed C2 rims... nirvana.

[tannhauser]

Campy Record brakes with salmon Koolstops and Hed C2 rims... nirvana.

Me!

[oldpotatoe]

how loudly did the customer scream when he saw this?:eek:

He brought all the stuff(bike and wheels) in..sponsored rider from DownUnder...not a happy camper, trying to get set for Kona. He has been having more than a 'few' problems with this bicycle...

[Chance]

Switched out a pair of DT road rims (19mm wide) for a set of Hed Belgiums (23mm wide). I'm using Dura Ace 7700 brakes.
................
................
Just wondering if this is an issue with most decent road brake calipers, or if newer ones may be more adapted to wider rims. Anyone notice this before?



For what it's worth, older Shimano Ultegra dual-pivot calipers worked well with at least up to 24-mm wide rims. And they had plenty of stopping power. Just guessing older 9-speed Dura Ace probably open enough too.

[Kontact]

One thing to play with is the centering screw. You can sometimes fudge the width or pressure by moving the screw then centering by hand.

[Chance]

I don't know that's it's bad practice to keep the cable "loose", but it's good to have a predictable engagement point. There is no absolute when it comes to cable tension -- it's personal preference.

One potential problem with leaving a brake cable with any slack is that the head end could become unseated in some brake levers. And if it snagged on next application you'd have little predictability.

Installation instructions when followed completely would never leave a brake cable with slack. At least not in my recollection for the ones on my bikes.

[tannhauser]

One potential problem with leaving a brake cable with any slack is that the head end could become unseated in some brake levers. And if it snagged on next application you'd have little predictability.

Installation instructions when followed completely would never leave a brake cable with slack. At least not in my recollection for the ones on my bikes.

Yes, that was the point in me adding the anecdote about my experience with v-brakes.

Referring to modern aero brakes where the hood covers the ferrule and bar tape secures the cable housing there is little to no chance of the detent to be other than what it needs to be.

[PacNW2Ford]

Doesn't really help the OP, but I have 23mm rims with:

Shimano BR-600 standard reach
Paul Racer-Ms
Paul Mini-Motos
Campagnolo Chorus 11 Skeleton dual-pivots

and all work fine.