Henry III

This is just a curiosity thing. But since I'm not big into U brakes. Since the brake boss location on them or pretty similiar. If I wanted to run some centerpulls inplace of a U brake? Will it just swap over? Just thought it would be cool to ditch the bulky U brakes and toss on some Mafac Racers instead.

I just thought since a lot of folks here like dropbar mtb's and a good percentage of them have u brakes. I think a vintage centerpull looks 10x's better then U brakes.

Velocivixen

I'm going to venture a guess and say no. The reason why is because when I bought my Fuji Sundance it came with roller cam brakes front & back, and I read up a lot on them. My understanding is that the brake mounts for roller cams and U brakes are the same - mounted higher than the rim vs. traditional cantilevers which are mounted below the rim. Everything I read gave the impression that the only brakes that would mount on those were U brakes or roller cams and no others.

So Im interested in what others have to say. Great question.

By the way, Hi from another Oregonian.

Bianchigirll 

I am going to say no also. If I follow you, your talking about ditching the Mafac center mount and putting it on the U bosses? I doubt the Mafacs will easily mount on the studs and then there is the whole reach thing.

If the reach is OK you may be able to remove the studs and just use the Mafacs mounted to the BB bridge but either way in the end you stil have a type of U or center pull brake and its eccentricities.

repechage

The situation is more than just the dimension relative to the wheel axle center and rim, the distance from centerline too. U brakes are big bulky mechanisms designed to swallow mtb. tires. In my referencing long ago, the only alternative for my Shimano U brake was a Campagnolo unit.
This was before the Paul centerpull brakes, but I do not know if the stud diameter is compatible.

John E

Based on personal experience with my Schwinn mountain bike, I believe U-brakes and Rollercams, which are indeed interchangeable with each other's bosses, live in a mounting world of their own.

mechanicmatt

Or you could get these:

mechanicmatt

Also, check BMX U-brakes for some other styles.

likebike23

The issue is the springs. On a U or roller cam, the spring is in the brake and there is no hole in the boss to attach the spring. The boss will accept either roller cams or u brakes.

Henry III

That's the one thing I wasn't sure about. It's been quite awhile since I've had u brakes apart.

Grand Bois

MAFAC Racers don't need a hole in the boss to attach the spring.

likebike23

Ok. Maybe you could elaborate on it a bit. When you don't contribute in any other way it sounds like you are simply trying to say I'm wrong. Maybe that's not what you are trying to do, but I don't know you and can't see you to judge what your intension is.

Grand Bois

What's so hard to understand?

fietsbob

Paul Comp also puts a Spring in each side around the mounting bolt..

Wheel axle to brake Boss Measurement , radius, will be useful in communicating with the Manufacturer. Break out the tape Measure !

likebike23

I'm just confused how you manage to attach the springs when everything I've seen shows either a brazed spring hole or a plate with a hole that slides onto the boss. Are those other people wrong too? If you have a special way of attaching the spring, perhaps you could share that valuable information.

Grand Bois

Do you always take such a nasty tone when someone dares to disagree with you? I can't see the pictures, but I'm sure they prove whatever your point is.

You win. I'll keep my ideas to myself.

likebike23

@Grand Bois: As the immortal Ditka would say "Come on man"! You are really going to play the butt hurt victim with your history of jabs toward anybody who didn't route their cables correctly or level their rack? I gave you an opportunity to back up your position and clarify your cryptic post to which you replied "What's so hard to understand?". Sorry for getting nasty in response to your being nasty, I should have let it go.

crank_addict

likebike23-
Both Mafac Competition and Racer have the long portion of the spring perched on the nut that retains the brake pad post. The short portion of the coil spring partially wraps around the brake arm. There are subtle differences between them.

BTW: If one has a brake boss in the stay with a removable post, you could thread a U brake's spring perch. DiaCompe made them. Also, depends on the frame / wheel mish-mash but one possibly could use the Comp or Racer series WITH the U-brake coil. Its goofy and don't really see the need to other than to be different. I do have some of these mentioned on hand and experimented doing such.

Right now, my fun is with the Mafac Comp. with a simple 2:1 MA leverage. Power brakes with using just a pinky fingy

Grand Bois

I've got Campagnolo, Shimano and Suntour U, Suntour roller, MAFAC Racer and Competition brakes here and a Peugeot that takes a U or roller. I think I could put together something that might work, but it's too cold in the garage to put it to the test. I don't think that a MAFAC would be an improvement over the Campagnolo, but it might be fun to experiment when it gets warmer. With a chain stay brake and horizontal dropouts like I have, you can adjust the position of the wheel to match the reach of the brake....to some extent.

Note that my posts are less cryptic now. That's because I'm no longer at work.

likebike23

Crank_addict: I saw those power brakes in the Frankenparts thread, pretty cool. I've never seen a U brake spring used on a Racer, I love those kinds of experiments. I'm still not fully understanding the Racer brake without the spring being fixed near the post on one end, but I'll look for pics.

likebike23

Fair enough. I seriously love tinkering with bikes and would welcome any of your ideas with positivity, if positivity is a real word.

crank_addict

^^ha, I was going to do the same but would have to drag some stuff out of the cold attic. As for the frankenbrake MAFAC Comp, I lost one of the special fiber washer due to my stupidity. When I overhauled them, cleaned all the parts in lacquer thinner and left one of those washers too long. Melted away and left me a blob. Fortunately Home Depot has them in close enough size 5/16 i.d x 9/16 o.d. yet still had to thin it down.

So with that drama, I was going to borrow one of the Racers washers to go on the Franken' 'Competition' but no go! But it was good to compare on the bench and learned the differences between them. You wouldn't know it looking at them assembled. They have different bushings / type, arm length, spring length, etc. I do have an older Specialized Stumpjumper hardtail project that might end up with the 'Racers' with the t 2:1 mod. It'll be quite awhile before I get to it.

Here's the final version of the MAFAC Comp's. Old pads are no longer up to the task. Working on some Scott Matthauser finned but modified with cartridge pad replacements.




Another potential would be the early Shimano 500 EX centerpulls. May or may not work to adapt, but the only way is to try and have enough other old stuff on hand for mix / match. Plus you might have to make bushings, spacers whatever.

crank_addict

of interest:
MAFAC Brake Bosses v. Canti Bosses : La Rueda Tropical

neat pics> https://www.flickr.com/photos/8210984...n/photostream/

crank_addict

Another wild idea is to thread insert/ bosses into the fork. No post are used but rather the brake arms mount directly and pivot on the fork. Sort of like the modern Trek Madone.

fietsbob

Kool Stop has 4 dot Replica Inserts, to slip right in .

but TRP adjust-in-place shoes may be good Too . Then, toe-in is adjustable.

repechage

Time to set up shop in the kitchen. Household harmony is overrated when there is bicycle work to do.