cuyd

Are caliper length extenders dangerous? I've heard so multiple times but I want to clarify this. There are various types, this one is looks apparently fine but such construction will get these bolts leveraged. So whole thing might snap at some point.



Possible alternative, extended brake pads. Almost brilliant except it looks to me that braking hard will cause them to roll around arm.


Am I correct? Are there any sensible alternatives to extended arm length brakes?

FBinNY 

On the right situation and given normal robustness of the involved frame parts, the answer is yes, they are OK,both safe and practical.

If they work for you, go ahead.

Andrew R Stewart 

On the first image, the linkage brake w/ drop bolt mounted to the curved bridge, the problem I see is the lack of a flat mounting pad brazed onto that bridge. No mater what type of pads or drop bolt involved the braking forces will more easily twist the caliper about the bridge.

A drop bolt maintains the tire clearance within the caliper, only the pad reach from the bridge is changed. With a drop pad the tire clearance (and fender) grows, but the caliper's leverage reduces. Pick your need or poison.

I'll make a comment about "So whole thing might snap at some point." Stuff that snaps when the rider is not expecting it is often because the rider didn't die the diligence and keep on top of their equipment and inspect periodically. Especially when running modded stuff. Andy

BCRider

The first one might not be ideal but at least it will retain the proper brake feel. The second one extends the arms and changes the ratio between the brake lever and pad arms. You'd have to squeeze a LOT harder to stop well with the second style. Think of the difference between lever effort needed with the old single pivot style vs the more modern and current double pivot calipers. Basically in the picture shown it'll reduce the pressure at the pads by enough to make the nice double pivot caliper shown behave more like a poor single pivot style... Might even alter it enough to "add" the amazing stopping power of chromed rims into the question to boot!

So if you really must alter the brakes I would go with the first drop bolt style. Yes, it will pivot on the brake bridge. But only until the bolt is riding hard on the edges of the hole.

dedhed

I've been running Bdop drop pads on Ultegra 6600 dual pivot calipers for years and probably 15K miles without issue either in braking effort or performance

​​​​​​https://bdopcycling.com/product/bdop...rs-set-silver/

oldukbkr 

A drop mount is sometimes used in the tricycle world to mount a second front brake behind the front fork, which requires greater reach. Especially on older frames where it is not possible to install rear brakes and we don't want to rely on a single front brake. I've done this myself with no problems although, to Andy's point above, I inspect before each ride.

cuyd

Thanks for all the answers. As I said I have serious considerations related to safety of such modifications. I know some people do use those successfully, but I've also heard bad stories. Those BDop pads look much better than those on picture that I've posted, that's because the offset is much smaller so perhaps they wouldn't be rolling around brake pad's bolt axis.

In my case, because the needed clearance is relatively small I have decided to use normal pads and just cut the top of the pad rubber(like 1/32 of inch) with box cutter. I'm also using longer V-Brake pads with road caliper brakes and I didn't notice much difference in braking power. Is there anything wrong with such setup?

FBinNY 

The length of the pads doesn't braking meaningfully. Brake friction simply a function of the frictional properties of the material, ie. rubber on aluminum, multiplied by the force pressing them together. Note that this is FORCE not pressure, so pad size doesn't factor.

That said, length does have subtle effects. Longer pads are more stable and less prone the the rim's movement causing them to toe out under load. OTOH, the greater length can make it harder for them to squeegee off water, and thus worsen wet braking.

As for shaving vs. replacing, I've with you here. However I prefer to use a coarse file or rasp to shave the top edges on a curve following that of the rim. This is especially better with longer pads. BTW- Koolstop and others make curved pads which may solve your problem with less or no shaving.

Andrew R Stewart 

Not at all. This trick is done in many shops without the rider even knowing. I'll use a bench grinder to bevel the top edge of pads. The other trick if only a mm or two of more reach is needed is to increase the pad mounting slot in the caliper arms. However this is a non reversable method that if done too much can result in a cracked/broken caliper arm. Andy

cuyd

I looked at it exactly this way. I guess that bigger pads might also last bit longer(assuming same material).