Anyone using direct mount road calipers?

[bicycletricycle]

Curious about these new fangled direct mount road calipers. The da 9010 brakes seem to be getting high marks, ee has a nice offering as well.

Anyone using these ? Anyone get a custom with these yet?

They look kinda cool. Better tire clearance, better performance (maybe)

[buldogge]

Getting ready to use one in the rear...Red Star Due will have the DA one mounted below the chainstays...SS/Fixed, short stays, track ends.

Still running Record Skeleton up front though (CF fork).

Just getting started cutting tubes...Maybe a mock-up in a few weeks...Painted/road-worthy by Spring, hopefully.

-Mark in St. Louis

[sandyrs]

Getting ready to use one in the rear...Red Star Due will have the DA one mounted below the chainstays...SS/Fixed, short stays, track ends.

Still running Record Skeleton up front though (CF fork).

Just getting started cutting tubes...Maybe a mock-up in a few weeks...Painted/road-worthy by Spring, hopefully.

-Mark in St. Louis

How will you accommodate the wheel moving in the track ends? You'll have to adjust the reach on the calipers?

[oldpotatoe]

Getting ready to use one in the rear...Red Star Due will have the DA one mounted below the chainstays...SS/Fixed, short stays, track ends.

Still running Record Skeleton up front though (CF fork).

Just getting started cutting tubes...Maybe a mock-up in a few weeks...Painted/road-worthy by Spring, hopefully.

-Mark in St. Louis

Back to the Future!!

I know..

[Peter P.]

Back to the Future!!

I know..

That's a good point, and something I didn't think about until you posted the picture of the U-brake:

The big problem with U-brakes was, as the brake pads wore they would arc toward the tire and it was very common to wear a hole in the sidewall. This was all due to the short span between the pivot and the brake shoe.

So is this an issue with direct mount ROAD brakes and no one is talking about it?

[mwynne]

I was asking some similar questions a few weeks back, might be worth checking out the feedback there too http://forums.thepaceline.net/showthread.php?t=180933&highlight=direct+mount

[lhuerta]

...here are a few pics of the new Campagnolo direct mount brakes. It is a shame, ...these are perhaps the ugliest Campagnolo calipers ever made. The two exposed direct mount bolts are unattractive compared to the hidden bolts on regular SR calipers.

[pbarry]

That's a good point, and something I didn't think about until you posted the picture of the U-brake:

The big problem with U-brakes was, as the brake pads wore they would arc toward the tire and it was very common to wear a hole in the sidewall. This was all due to the short span between the pivot and the brake shoe.

So is this an issue with direct mount ROAD brakes and no one is talking about it?

I built a Merlin road frame with a chainstay mounted WTB Mini Roller Cam brake for my gf at the time. The brake came with washers that were added between the arm and shoe as the pads wore. Have no idea about the need for that adjustment on the new brakes.

[unterhausen]

I'm going to build a frame with Paul Racers direct mounted, does that count? Have another frame that's going to get something else direct mounted, haven't figured out what yet. Maybe MAFACs

Do the Campagnolo direct mount actually have a cross bar that's bolted to the frame? That seems a little pointless

[thirdgenbird]

Do the Campagnolo direct mount actually have a cross bar that's bolted to the frame? That seems a little pointless

Yes. It's a hollow bit that covers the spring. It appears to be the same as the spring and cross bar on an ee direct mount, just hidden behind the arms. I haven't seen a campy caliper up close, but I'm suspicious they use the cross bar to help adjust left to right tension.

Bontrager direct mounts also have a cross bar.

[oldpotatoe]

...here are a few pics of the new Campagnolo direct mount brakes. It is a shame, ...these are perhaps the ugliest Campagnolo calipers ever made. The two exposed direct mount bolts are unattractive compared to the hidden bolts on regular SR calipers.

How else ya gonna bolt them to the frame/studs?

[kgreene10]

I've got direct-mount Bontrager Speed Stop brakes on my Emonda SLR. I have very few miles on the bike, but they have worked very well so far. I would need to get into the mountains to decide if they are better than standard-mount DA9000 brakes.

[Likes2ridefar]

I had them on my parlee esx. One of the reasons i sold the bike was because of them. The seatpost being the other.

The rear was mounted below the chainstays and besides getting dirty it was not good at stopping. Felt terrible too. It was duraace 9000.

The front was fine but didnt feel any nicer than the more common one bolt mount.

[buldogge]

Yeah...Brakes will have to be adjusted. I will try to set it up with the most range possible in relation to the pad slots...in both directions.

Realistically this is a relatively low use bike...one in a quiver, if you will.

If I was using it in a track situation, the caliper would be removed anyway, and gearing changes/chain length/axle position wouldn't be an issue.

Mainly, aesthetically, I want slender seat stays with no caliper mounted.

-Mark

How will you accommodate the wheel moving in the track ends? You'll have to adjust the reach on the calipers?

[pdmtong]

Back to the Future!!
I know..

I had a set up just like that - XT U with a shark fin.

Why did the CS placement always feel so spongy?

[JMacII]

Sorry, what's the point of these? Weight? Better braking?

[buldogge]

TBH, I have no idea...in my case, it is purely aesthetics/packaging!

-Mark

Sorry, what's the point of these? Weight? Better braking?

[zetroc]

My one issue with these brakes is the terminology - it seems like the manufacturers are insinuating that other brakes mount indirectly.

I do have a bike with Paul Racer Mediums mounted on posts, and they brake very well.

[marciero]

My one issue with these brakes is the terminology - it seems like the manufacturers are insinuating that other brakes mount indirectly.

I do have a bike with Paul Racer Mediums mounted on posts, and they brake very well.

The version of these that mount directly onto fork braze-on pivots are lighter and stiffer than the ones that mount to a center hole in the fork, since the latter essentially add a plate that the pivots attach to. This is the idea with "direct mount" brakes, which share that design feature with Paul Racer/Mafac -type centerpulls.
The actuation is obviously different.

[bikinchris]

A lot of time trial bikes use direct mount style brakes. It makes me money because they are total trash and I have to work on them almost constantly. Those companies should be ashamed of themselves. Frankly, it's a safety issue.

[bicycletricycle]

Are the shimano ones crap as well?

I've heard that the giant and trek branded ones are terrible but figured the shimano ones might be okay.

[Mark McM]

That's a good point, and something I didn't think about until you posted the picture of the U-brake:

The big problem with U-brakes was, as the brake pads wore they would arc toward the tire and it was very common to wear a hole in the sidewall. This was all due to the short span between the pivot and the brake shoe.

So is this an issue with direct mount ROAD brakes and no one is talking about it?

Each pivot on the direct mounts is at about the same offset as the offset pivot on traditional dual pivot brake. Therefore, the pads on directly mount brakes will arc upward as the pads wear about as much as the pad on the offset arm of a traditional dual pivot brake.

[559Rando]

Curious about these new fangled direct mount road calipers. The da 9010 brakes seem to be getting high marks, ee has a nice offering as well.

Anyone using these ? Anyone get a custom with these yet?

They look kinda cool. Better tire clearance, better performance (maybe)

when they came out Jan Heine had a blog post how they're essentially centerpulls. He's a big advocate for centerpulls on brazeon posts.

I have Dia Compe 750s on braze on posts on my custom. They're great.

https://c2.staticflickr.com/6/5037/14453449091_ea77bcd4c6.jpg
link (https://flic.kr/p/o2cGS8)

[EDS]

Are the shimano ones crap as well?

I've heard that the giant and trek branded ones are terrible but figured the shimano ones might be okay.

I think you are conflating three different types of brakes (v brakes on the Giant Propel versus direct mount center pull brakes on the Trek Madone versus the Shimano direct mount dual pivot).

[559Rando]

Here's the link to Jan's blog posting:

https://janheine.wordpress.com/2012/06/10/new-dura-ace-inspired-by-classic-technology/

and what he said about the brakes:

Not only does Shimano offer a centerpull brake, but they even offer it for use with brazed-on pivots. From back in the very first issue of Bicycle Quarterly, we have advocated brazed-on pivots to reduce flex and improve stopping power. This also reduces the weight and makes the brakes more elegant. In Shimano's case, the main advantage appears to be the ability to tuck the brake into the fork crown of time trial bikes. I think it will only be a matter of time until the brazed-on (or glued-on) pivots will show up on road bikes as well.

The new Dura-Ace brakes also are optimized for wider rims following the trend of professional racers toward wider (25 mm) tires. I am afraid that they still won't fit over a 32 mm tire with fenders, much less a Grand Bois Hetre, but it's a step in the right direction.

[guido]

I'm putting Paul Racers on the 650B project currently under construction...

[bicycletricycle]

I think you are conflating three different types of brakes (v brakes on the Giant Propel versus direct mount center pull brakes on the Trek Madone versus the Shimano direct mount dual pivot).

yes, i am.

wondering which ones bikinchris was talking about

[marciero]

when they came out Jan Heine had a blog post how they're essentially centerpulls. He's a big advocate for centerpulls on brazeon posts.

I have Dia Compe 750s on braze on posts on my custom. They're great.

https://c2.staticflickr.com/6/5037/14453449091_ea77bcd4c6.jpg
link (https://flic.kr/p/o2cGS8)

Would be the big question for me with 650b custom-centerpull or just go with Paul touring, which, frankly, are pretty awesome on my current 650b.

[bicycletricycle]

paul centerpulls feel and work better than paul cantis in my experience.

i have had direct mounted racers and medium racers, they both work extremely well.

[Mark McM]

Here's the link to Jan's blog posting:

https://janheine.wordpress.com/2012/06/10/new-dura-ace-inspired-by-classic-technology/

and what he said about the brakes:

Not only does Shimano offer a centerpull brake, but they even offer it for use with brazed-on pivots. From back in the very first issue of Bicycle Quarterly, we have advocated brazed-on pivots to reduce flex and improve stopping power. This also reduces the weight and makes the brakes more elegant. In Shimano's case, the main advantage appears to be the ability to tuck the brake into the fork crown of time trial bikes. I think it will only be a matter of time until the brazed-on (or glued-on) pivots will show up on road bikes as well.

The new Dura-Ace brakes also are optimized for wider rims following the trend of professional racers toward wider (25 mm) tires. I am afraid that they still won't fit over a 32 mm tire with fenders, much less a Grand Bois Hetre, but it's a step in the right direction.

Uh oh. Do we have to have another round of pointing out the flaws in Jan Heine's blog posts?

Shimano's direct mount brakes are not centerpull brakes. They are dual pivot sidepull brakes. Unlike in a center pull brake, the arms of dual pivot brakes are interlinked. This provides two features:

1) The arms on dual pivot brakes always articulate in unison. This is why dual pivot brakes need only a single return spring. Centerpulls may articulate unevenly, depending on pivot friction and spring tension. This united articulation allows dual pivot brakes to be centered more repeatedly, which also allows them to be set-up with less pad clearance (since the pads will always retract evenly).

2) The interlinking of the arms increases the overall leverage of the brakes. Traditional dual pivot brakes (with only one pivot offset) typically have a leverage ratio of 1.5:1. Direct mount brakes, with both pivots offset, typically have a leverage ratio of close to 2:1. In comparison, centerpull brakes typically have leverages closer to 1:1. The leverage of the caliper amplifies the cable force, so that dual pivot calipers generate more braking force for a given hand lever force.

Shimano's direct-mount brakes are actually very similar to the orginal dual pivot brakes from the 1960's, the Altenburger Syncron brakes:


http://www.mytenspeeds.com/My_TenSpeeds_1/Bicycles_Table/English_Bicycles/Phillips_Bicycles/PhillipsWPegBrakeCaliperRear.jpg




In the photo below from the back of the Altenburger brakes, the interlinking can be seen. Specifically, notice that the lower arm (longer cable arm) has nylon bushing that pushes upward on a stub arm extending from the upper arm (shorter cable arm). Note too that there is only one return spring, on the pivot on the left. This mechanism is very unlike a centerpull brake, were the two arms are semi-independent.

http://velobase.com/CompImages/Brakes/640430BD-F6D9-41D8-BE9C-3C0CBD889F09.jpeg

[559Rando]

Would be the big question for me with 650b custom-centerpull or just go with Paul touring, which, frankly, are pretty awesome on my current 650b.

You quoted the photo of my bike, but it does not 650B wheels and tires. I like the centerpulls for a few reasons and am glad I went with them over cantilevers.

[phutterman]

Semi-OT, but related, but does anyone know if the braze on locations are the same for the DA (or other modern road direct mount calipers) and the (shorter) Paul Racer Mediums? Just academic curiosity.

[bicycletricycle]

The leverage ration of mafac style centerpull or cantilever brakes is not fixed, you can raise or lower the straddle cable hanger. Depending on the starting layout of the brakes this can change the performance of your brakes quite a bit.

The interlinking of the arms does not in itself increase or decrease the leverage ratio. You can design a side pull road caliper with any leverage ration you desire by changing the lengths of the arms, pivot locations, etc.

Not sure if uneven actuation of arms is ever a real problem but that is a difference.


Jan was focusing on some things that are actually similar between the systems

1. They have two major pivots, one for each arm. (as opposed to the now basically extinct single pivot calipers)

2. The pivots attach directly to the frame and not through some kind of intermediate plate.

I don't think this really proves anything but what Jan was pointing out is true(ish)

Old WTB roller cam brakes are an interesting example of how a basic arm layout can be actuated lots of different ways with different results in leverage ratio and effectiveness (multiple profile roller CAMs, multiple profile toggle CAMs and now a new lever link) some are center pull, some are side pull.

anyways, I think one can talk about the optimal layout of rim brakes forever.

I was just curious if the new shimano ones worked well or not

Uh oh. Do we have to have another round of pointing out the flaws in Jan Heine's blog posts?

Shimano's direct mount brakes are not centerpull brakes. They are dual pivot sidepull brakes. Unlike in a center pull brake, the arms of dual pivot brakes are interlinked. This provides two features:

1) The arms on dual pivot brakes always articulate in unison. This is why dual pivot brakes need only a single return spring. Centerpulls may articulate unevenly, depending on pivot friction and spring tension. This united articulation allows dual pivot brakes to be centered more repeatedly, which also allows them to be set-up with less pad clearance (since the pads will always retract evenly).

2) The interlinking of the arms increases the overall leverage of the brakes. Traditional dual pivot brakes (with only one pivot offset) typically have a leverage ratio of 1.5:1. Direct mount brakes, with both pivots offset, typically have a leverage ratio of close to 2:1. In comparison, centerpull brakes typically have leverages closer to 1:1. The leverage of the caliper amplifies the cable force, so that dual pivot calipers generate more braking force for a given hand lever force.

Shimano's direct-mount brakes are actually very similar to the orginal dual pivot brakes from the 1960's, the Altenburger Syncron brakes:


http://www.mytenspeeds.com/My_TenSpeeds_1/Bicycles_Table/English_Bicycles/Phillips_Bicycles/PhillipsWPegBrakeCaliperRear.jpg




In the photo below from the back of the Altenburger brakes, the interlinking can be seen. Specifically, notice that the lower arm (longer cable arm) has nylon bushing that pushes upward on a stub arm extending from the upper arm (shorter cable arm). Note too that there is only one return spring, on the pivot on the left. This mechanism is very unlike a centerpull brake, were the two arms are semi-independent.

http://velobase.com/CompImages/Brakes/640430BD-F6D9-41D8-BE9C-3C0CBD889F09.jpeg

[bicycletricycle]

Semi-OT, but related, but does anyone know if the braze on locations are the same for the DA (or other modern road direct mount calipers) and the (shorter) Paul Racer Mediums? Just academic curiosity.

doesn't look like it.

[marciero]

You quoted the photo of my bike, but it does not 650B wheels and tires. I like the centerpulls for a few reasons and am glad I went with them over cantilevers.

Got it. Much of these deliberations for me are in the context of 650b, since that is the bike I would be likely to try them on.

Would like to see a modern dual pivot direct mount sidepull with just a bit more clearance than this latest crop, just to have side-pull alternative to Paul Racer, Compass.

[559Rando]

Got it. Much of these deliberations for me are in the context of 650b, since that is the bike I would be likely to try them on.

Would like to see a modern dual pivot direct mount sidepull with just a bit more clearance than this latest crop, just to have side-pull alternative to Paul Racer, Compass.

If you're going to use fenders, the clearance on centerpulls might make the most sense.

[Mark McM]

The leverage ration of mafac style centerpull or cantilever brakes is not fixed, you can raise or lower the straddle cable hanger. Depending on the starting layout of the brakes this can change the performance of your brakes quite a bit.

This is a common misconception. Changing the straddle cable angle only has a significant affect on the leverage of low-profile cantilevers, and not high profile cantilevers or most centerpull brakes, like the Mafacs:

http://velobase.com/CompImages/Brakes/316743EE-4730-46CA-A858-C2CB55EA84E6.jpeg
http://mombat.org/Stump0375Brake.JPG


The reason is simple. Torque generated on the caliper arm is proportional to component of applied force that is perpendicular to the lever arm. This means that for caliper arms that are substantially horizontal, the torque on the arm is affected only the vertical component of the cable force. The vertical component of the straddle cable force is not affected by the angle - each end of the straddle cable has a vertical force equal to half of the total vertical cable force. (Further, this means the primary affect of the straddle cable is to cut the force on each caliper arm to only half force in the main cable).

The interlinking of the arms does not in itself increase or decrease the leverage ratio. You can design a side pull road caliper with any leverage ration you desire by changing the lengths of the arms, pivot locations, etc.

Depending on geometry, linkages can be designed to either increase or decrease ratio. But the standard dual pivot sidepull design definitely does increase ratio.

While it is technically true that you can vary the ratio of a non-linkage sidepull brake by varying the arm lengths, in reality it is not practical to increase the ratio much beyond 1:1. The length of the pad arm can not be too short for reasons of tire clearance and travel arc, so instead the cable arm must be lengthened to increase ratio. But if the pad arm is already 50 mm long, you must use a 100 mm cable arm to achieve the 2:1 ratio of Shimano Direct Mount brakes. that means that the cable arms (and the cable itself) has to stick out 4" from the brake pivot - a very cumbersome arrangement. However, employing a linkage of some type (as on dual pivot brakes) allows one to increase leverage ratio while remaining within a small package.

Not sure if uneven actuation of arms is ever a real problem but that is a difference.

It becomes more of an issue as the leverage ratio increases. The higher the leverage ratio, the shorter the pads travel for a given lever motion. Therefore, the higher the ratio, the narrower the pad/rim clearance must be. If the arms aren't linked, small variations in retraction force or friction can affect how far a pad retracts, so the smaller the pad clearance, the more likely that there will be pad rub if the pad doesn't retract far enough. Since the dual pivot linkage mechanism guarantees even and consistent pad actuation/retraction, pad rub can be eliminated even at high ratios/low clearances.


Jan was focusing on some things that are actually similar between the systems

1. They have two major pivots, one for each arm. (as opposed to the now basically extinct single pivot calipers)

2. The pivots attach directly to the frame and not through some kind of intermediate plate.

These are distinct advantages of the Shimano Direct Mount brakes. But again, that doesn't make them centerpull brakes, as not all centerpull brakes use pivots attached to the frame, such as these Mafac centerpull brakes:

http://thecabe.com/vbulletin/images/imported/2013/08/image1277-1.jpg

[marciero]

This is a common misconception. Changing the straddle cable angle only has a significant affect on the leverage of low-profile cantilevers, and not high profile cantilevers or most centerpull brakes, like the Mafacs:
The reason is simple. Torque generated on the caliper arm is proportional to component of applied force that is perpendicular to the lever arm. This means that for caliper arms that are substantially horizontal, the torque on the arm is affected only the vertical component of the cable force. The vertical component of the straddle cable force is not affected by the angle - each end of the straddle cable has a vertical force equal to half of the total vertical cable force. (Further, this means the primary affect of the straddle cable is to cut the force on each caliper arm to only half force in the main cable).


This analysis neglects the force at the pad.
Is true that the force at the arm is due only to the component of straddle cable force in the direction of rotation. But the force at the pads is what is important here.
Changing the straddle cable angle, making it closer to horizontal, does in fact decrease component of force in direction of rotation at the arm (bad) but also has the effect now of rotating the arm less when you pull on the cable. (If the cable were horizontal, pulling the cable a tiny amount would not turn the arm at all, and in fact the component of force in direction of rotation would also be zero.) And so the brake pad moves a shorter distance. In fact the leverage ratio, or mechanical advantage, and force at the pad is multiplied by the same ratio of distances. To see this you could imagine pulling up on the brake cable with force F1, with the brake engaged, and now imagine moving the yoke upward a tiny amount further d1 with against the force F1. (You must imagine since if we assume no flex in system nothing would move at all) The work done at the cable would be simply F1*d1. The work that would be done by the pad, F2*d2, would have to be equal, so F2=F1*d1/d2, with d2 smaller for more horizontal straddle. This effect is like that of a simple lever/fulcrum device. (I'm sure that mechanical engineers will recognize this method of virtual work to compute force. A rigorous analysis of the multiplying force and dependence on the geometry, though non-trivial, should not be that difficult.)
High profile cantilevers offer the greatest range of adjustment. Of course, there are practical considerations like the need for enough travel to overcome flex, etc. to limit the multiplying force.

[bicycletricycle]

I agree

This is a common misconception. Changing the straddle cable angle only has a significant affect on the leverage of low-profile cantilevers, and not high profile cantilevers or most centerpull brakes, like the Mafacs:

http://velobase.com/CompImages/Brakes/316743EE-4730-46CA-A858-C2CB55EA84E6.jpeg
http://mombat.org/Stump0375Brake.JPG


The reason is simple. Torque generated on the caliper arm is proportional to component of applied force that is perpendicular to the lever arm. This means that for caliper arms that are substantially horizontal, the torque on the arm is affected only the vertical component of the cable force. The vertical component of the straddle cable force is not affected by the angle - each end of the straddle cable has a vertical force equal to half of the total vertical cable force. (Further, this means the primary affect of the straddle cable is to cut the force on each caliper arm to only half force in the main cable).



Depending on geometry, linkages can be designed to either increase or decrease ratio. But the standard dual pivot sidepull design definitely does increase ratio.

While it is technically true that you can vary the ratio of a non-linkage sidepull brake by varying the arm lengths, in reality it is not practical to increase the ratio much beyond 1:1. The length of the pad arm can not be too short for reasons of tire clearance and travel arc, so instead the cable arm must be lengthened to increase ratio. But if the pad arm is already 50 mm long, you must use a 100 mm cable arm to achieve the 2:1 ratio of Shimano Direct Mount brakes. that means that the cable arms (and the cable itself) has to stick out 4" from the brake pivot - a very cumbersome arrangement. However, employing a linkage of some type (as on dual pivot brakes) allows one to increase leverage ratio while remaining within a small package.



It becomes more of an issue as the leverage ratio increases. The higher the leverage ratio, the shorter the pads travel for a given lever motion. Therefore, the higher the ratio, the narrower the pad/rim clearance must be. If the arms aren't linked, small variations in retraction force or friction can affect how far a pad retracts, so the smaller the pad clearance, the more likely that there will be pad rub if the pad doesn't retract far enough. Since the dual pivot linkage mechanism guarantees even and consistent pad actuation/retraction, pad rub can be eliminated even at high ratios/low clearances.




These are distinct advantages of the Shimano Direct Mount brakes. But again, that doesn't make them centerpull brakes, as not all centerpull brakes use pivots attached to the frame, such as these Mafac centerpull brakes:

http://thecabe.com/vbulletin/images/imported/2013/08/image1277-1.jpg