6

I rebuilt an old Peugeot and swapped out the old steel rims for new alloy rims. I then cleaned the existing caliper brakes and put on new brake pads and cables, but they just don’t stop the bike. So I bought new Shimano brake pads designed for AL rims + caliper brakes, but same issue - no stopping power! The rims keep going even with full braking pressure applied?

Any ideas?

Improve this question
4
  • 5
    Welcome to the site - could you please add a photo of your brakes using edit ? Ideally one with the lever open and the other with the brake applied. It could be angles/tolerances in the alignment of pads, or in the cable and photos will help clear that up.
    – Criggie ♦
    Dec 27, 2022 at 23:18
  • 2
    I assume you have sufficient cable tension and the lever is not hitting the handlebars?
    – Michael
    Dec 28, 2022 at 8:43
  • 1
    Can you say exactly what you mean by '…with full braking pressure applied'? Does that mean at the handlebar end, you're squeezing the levers as hard as you can, or are you somehow measuring what power is actually applied to the wheels by the brakes?
    – Robbie Goodwin
    Jan 24 at 21:43
  • 1
    Did you get this solved? I also have an early-80s Peugeot (Corbier) that I replaced the original bent steel wheels with alloy on. I also have terrible braking power now. I have cleaned the braking surfaces with an automotive painter's solvent for paint gun cleanup, and with some other no-residue volatile solvent. I also took the brake pads and exposed some new rubber material using the belt sander, as some aluminum dust was embedded in the pads. I adjusted them to make even contact across the whole braking surface, and so there is minimal travel to make initial contact. It's still crap.
    – RHBronco
    Oct 2 at 21:48

2 Answers 2

Reset to default
5

You may have already done this but make sure the new brake pads align with the rim so that the flat face of the brake pad is completely touching the surface of the rim. If it is at an angle then you will have much reduced effectiveness of the brakes.

I would also be looking at the cable tension and that there is enough travel on the brake levers to apply sufficient pressure for the brake pads to grip the rim.

I also assume that you are using the same width rim as this could also be the cause of the issue. If the rim is thinner than the old ones the brakes may not be gripping the rim correctly reducing the effectiveness of the brakes.

Improve this answer
2
  • Aren't rim brakes supposed to have a certain amount of toe-in?
    – DavidW
    Jan 24 at 12:06
  • 3
    @DavidW yes, but they should stop adequately without toe in. One thing that Oliver didn’t mention is that wiping the rim down with rubbing alcohol may help by removing any surface contaminants. Same goes for the brake pads. Oliver, you can consider adding this to your answer if you agree and find it helpful
    – Weiwen Ng
    Jan 24 at 12:26
0

Is there a chance your rim diameter changed?

It would be reasonable for the original rim to be a 630mm because that was the style of the time, and for the newer rim to be a 622mm.

That results in the rim being 4mm smaller on each side, so the brake pad has to move down that far to be on the brake-track.

This alters the ratio of leverage giving less mechanical advantage overall.

One solution is to change to longer-reach modern dual pivot calipers, or to try and "drop" the entire caliper down with some kind of drop-bolt or mounting plate.
New caliper costs a fair amount, but brakes are not somewhere you want to skimp. Whereas a drop mounting can be a bit sketchy.

Example of both a modern caliper and still needed a drop plate, and yet the brake pads are still close to bottom of adjustment slot. enter image description here

Improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.