I'm trying to upgrade the brakes on my partner's 80s Raleigh mixte frame from the old Weinmann side-pulls to a modern set of dual callipers.

As you can see from the photos, the current rear brake is an "upside down" version of the classic side pull, to allow the cable to be run from the long middle tubes below and up to the calliper. My new brake is of course just a standard one where the cable runs out of the top of the calliper. So I'm guessing I should just mount the new brake on the flat metal bridge between the long middle tubes? That would provide the straightest line for the cable...

Which brings me to my problem. The bolt supplied with the new rear brake looks far too long to be able to mount to the thin flat plate. The nut would need to screw on further than the thread of the bolt will allow (see the threadless area on the calliper bolt).



How can I get around this problem?

Should I remove the curved washers (seeing as they won't help in this case) and find some thick washers to take up the surplus space on the bolt? Would this be secure/stiff enough when braking?

Or should I try finding a shorter bolt (I'm not too keen on this as it will involve disassembling a brand new part).

Or should I send this one back and swap for a calliper with a different fixing? If so, what type of dual pivot calliper would fit best?

Try routing the cable housing up the seat tube and a couple inches before your hit the seat lug, curve back down to the brake. Buy a couple of metal or plastic cable housing stays (like those for fixie frames that don't have braze-ons).

there are other Brakes made such that the cable clamp and the housing stop are reversible
so the housing can come up from the bottom or top.. Tektro makes those..

the bolt that holds it on can be threaded down further , or you cam put a spacer under the nut. to fill the excess length.

FWIW, ,my Brompton uses both brakes with bottom route cables.. putting a rubber bellows off a V brake
keeps water from easily running into the housing and rusting it.. ,


new housing and cable and fresh Brake pads may have been sufficient.. .

particularly given the Front is the real Braking force.

the other place to put the brake is the lower mixte top tube.. center pulls work , there, the cable pull is then straight.

Thanks gyozadude - I thought of that originally, but won't that reduce braking performance? Mounting the brake in the lower position seems like a much more elegant solution - more aesthetically pleasing too.

If I stack the curved washers supplied on the nutted side of the plate, that provides enough thread to get the nut on tight. I won't actually fit this with the curved washers but if I use a spacer (about 10mm) do you think that will be a secure enough fixing?

Also the mounting hole on the flat plate is kind of an oval shape. Could that cause a problem? I'm thinking it should be fine so long as I mount to the bottom edge of the hole (in the direction the brake will pull) and fasten it nice and tight...right?

Seems like I'm talking myself towards to a solution But I just want to check that I'm not doing anything seriously wrong mechanically here...it is a brake after all!

I would have looked into those if I had thought ahead...oh well!

I agree. But I've found the existing ones such a pain to adjust - I just want something modern, easy and more reliable so I don't have to worry about my partner out there on the road!

Yes and Yes. It will degrade performance and it doesn't look as aestehtically pleasing. But it may not degrade that much, which is why I'd probably try that first, and then I'd try to find aesthetically pleasing cable clamps and paint them to match the frame. I'm routed cables that way in the past and surprisingly, the brakes still work fairly "crispy."

If you are moving to try and reverse the function of the existing hardware, be aware that the challenge will be to come up with a functional way to cantilever either the cable pinch bolt and brake QR assembly, or to cantilever the cable housing stop and tension adjuster barrel assembly. If you want to make it aesthetically pleasing, it probably requires some machining to make it look less than hokey (and still be reliable and lined up for the pull and still allow the brake to open wider to remove during wheel exchanges). Would your technique still allow for that?

I'm hard pressed to find a dual pivot brake that has reversible pinch bolt and qr assembly. But that might be the most aesthetically pleasing way to do it.

If you ask me, dual-pivots on the rear are a bad idea 99% of the time. They're too powerful to allow for good modulation when the wheel can lock up so easily.

I'd just keep using the old rear brake. A DP on the front is both necessary and sufficient.

That said, assuming you want to use the new brake anyway, instead of mounting it on a flexy bit of thin plate with a goofy-looking spacer making up for the long spindle, I'd mount the brake in the upper position and use a V-brake noodle or two to allow the cable to run along the seat tube for a bit and enter the brake from above as intended.



V-brake noodles are the answer to many a cable-routing nightmare. They can be bent or shortened if necessary.

I had to shorten one recently to fit V-brakes to a bike that only had that little s-shaped tube around the seat tube for cantis... I filed the end of the tube more square and used an old-style acorn to mate a short length of housing to it, running to a shortened noodle.

Center pull mounted lower, transverse cable passes around the seat tube. is pulled from the front.

was a common set up, 'back-in-the-day'.

Yes mounting on the center is better and basically correct for this bike. You will want to route your cable through holes in the frame between the two top tubes this may require section of bare cable bewtween the front hole and a couple of furrels.

+1

I've done that mod myself once and was very pleased with the outcome.

OP; That actually looks almost like a front brake which just happened to end up with the washer set intended for a rear brake on a bike with a round tube style brake bridge. If it was for the front, the curved washer/spacer would have a larger radius to match up to the fork better.

1) Since you have the brake as it is and you have a flat plate style break bridge, relocate those special rear washer/spacers to the parts bin as you don't need them here.
2) In past ages one could sometimes buy a replacement center bolt for a broken one or to refit a front to rear or rear to front. Probably not today through. I wouldn't bother chasing it.
3) Yes is is possible to thread the bolt down further, but many are hardened and chromed making them tough to cut with a threading Die. Seems more trouble than its worth unless you already have a set of dies and know how to do the job.
4) So you basically need to add a "really thick" spacer or a stack of washers to take up the extra shaft length. These are hardware items and an inch worth of them should be about a dollar US. If you can find them, special washers which are larger in diameter while still having a small center hole would be ideal to spread the clamping force. These are generally called "fender washers" and will often be a bagged item vice ones that would be in a bin on the shelf. Just ask the store help for some 3/16" fender washers (or the metric size if so inclined).
5) As long as you don't shorten up the housing so much that it binds the brake movement, the brake couldn't care less if the install is top or bottom cabled. For some models the bolts that hold/stop the housing and the one that do the cable clamping can be swapped to do the job. Consider if the ones from the old brake can be applied to the new one (if so buff them up to make the match better)...
6) If you can, you might want to switch to a rear rack with a different mount to get it out from under the brake bolt as the rack will try to sway under load and in turns which can break the bolt or cause it to loosen over time. Even on a frame without rack braze-ons, most modern racks can be mounted easily using P-Clamps (more correctly called Adel clamps). Get the ones with a rubber or nylon sleeve to protect the frame. At most hardware stores and auto parts stores.
7) Last tidbit; The lower quality caliper brakes used on the rear can tend to shutter, vibrate and squeal as the braking action bends the arms towards the front which then pivots the pads off the rims a bit letting them release and jump backwards to re-stick and repeat... It is simple to avoid by simply mounting the rear brake backwards (i.e., on the other side of the plate). That way both the front and rear brakes take the same toe in magic in the same way and all braking energy is trying to stretch metal in the arms, which is much harder than bending it. This is far from obvious, but give it a try! I have never seen it fail to really improve braking (on top of the line brakes like a Campy, it won't matter as those have very, very stiff arms).

Hope that helps some
/K

Thanks all. I think I'm going to try a spacer along with a large diameter washer as per ksisler's suggestion. If I'm happy with it once it's mounted I'll proceed to fit the new cables...if not I'll try mounting to the seat stays with v-brake noodle method.

I'll come back with pics of the finished result over the weekend!

For once I agree with you. I've done it more than once Using MAFACs. A longer than original transverse cable may be required.

It's possible to use a standard side pull by running the cable up the seat tube and down to the brake, but you'll end up with a sharper bend than is optimal for brake cables and it's not easy to find 1 1/8" brake cable clamps.