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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?

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    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
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    I assume you have sufficient cable tension and the lever is not hitting the handlebars?
    – Michael
    Dec 28, 2022 at 8:43
  • 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? Jan 24 at 21:43

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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.

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  • Aren't rim brakes supposed to have a certain amount of toe-in?
    – DavidW
    Jan 24 at 12:06
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    @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

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