How to improve front brake functionality?

Question

My front brake (cantilever brakes) does not make contact with the rim until I pull the brake levers almost all the way in, leaving me with very little space to apply extra force. That means the brakes are not working very well to slow down or stop the bike.

I'm not sure what I need to adjust -- whether it's the transverse cable or the link wire. Moreover, when I try to tighten the transverse cable, the brakes work well for a few times (or "pumps") but then suddenly revert to their original functionality. I'm not sure what's going on (if the brake cables are coming lose for example under the tension).

Any thoughts? Thanks.

Answer 1

It sounds like the cable's slipping after you adjust it.

Precisely how you adjust the cable depends on the brake design, and normally you would not shorten the straddle cable, since it needs to be a certain length for optimum operation. However, with many newer bikes the main cable makes up half the straddle cable, with a spacer to maintain the proper straddle length.

Sheldon Brown has an article on cantilever adjustment, though it's a little short on actual adjustment operations. Park Tool's article, on the other hand, almost goes into too much detail.

Answer 2

It depends on what sort of transverse setup you have.

If you have the one-piece where the brake cable goes through the block then out one side (while the other side is held with a fixed spacer cable), then your slippage point will be where the cable is attached to the end of the lever arm.

However, if you have the two-piece design (brake cable terminates at the block and a separate transverse cable connects the lever arms), then you need to look at how the cable attaches to both lever arms AND the transverse block.

If it tightens up to start with and then slips, look at all the tightening bolts. It's possible there is a stripped one in there which tightens up to a point but fails under stress.