Centering caliper (side-pull) brakes

[Chris S]

I've just adjusted the caliper brakes on my Raleigh. On brake block is now a lot nearer the rim then the other.

According to my Haynes manual the brakes should be centred by rotating the brake body using a spanner. However my brake body appears to be fixed in one position, it doesn't even have the flats for the spanner.

Does it really matter if side-pull brakes aren't centered? The braking force is disproportionately greater on one side than the other no matter where the brake blocks are.

 

[tyred]

Are these the traditional single pivot design? If so, centering them can be tricky but is possible. It doesn't matter too much if they are not completely centred so long as one of the pads isn't dragging on the rim, a common complaint with this type of brake.

Work a little light oil (just a few drips) into the pivot and adjust the front nuts until both arms can move freely but free play is minimised. This will reduce judder. If there is a lot of play still, take it apart and take up the wear with a bit of an old fag packet as a shim. The nut which holds the caliper to the fork can then be slackened slightly and the caliper rotated until it sits central. Then tighten the nut, making sure the caliper doesn't move again. Some better versions have flats on the inside behind the spring to hold it with a spanner but a very thin spanner is usually required.

If this bike is an old Raleigh "light" Roadster, the design is slightly different as there are no nuts to the front but the principle is the same. The nut which holds the caliper to the frame adjusts everything.

If it's a modern dual pivot, it's easy. Just slacken the caliper mounting (probably an Allen key fitting) and rotate the caliper into place, hold it there and tighten.

 

[Chris S]

RE: "The nut which holds the caliper to the frame adjusts everything."

Thanks - it is an old Raleigh, I'll give this a go.

 

[ColinJ]

I just get hold of both sides of the brake assembly and pull it in the direction I want. It usually only takes a mm or so of movement. I check that it is right by squeezing the brake lever slowly and watching to see if the rim deflects. Both blocks should contact the rim at the same time so it shouldn't deflect under braking.

If you don't make sure that the brakes are centred, you will wear the block on one side much quicker than the other.

 

[tyred]

With Raleigh branded calipers, just be careful because if you over-tighten the mounting nut, the spring will not be strong enough to release the brake.

With single pivot calipers of any type, if the brakes don't appear to release properly, I sometimes have found it helpful to unhook the spring from the arms of the caliper and give it bend outwards as they can lose tension over the years.



You might like to read Sheldon's guide to servicing the English Three speeds as they have a few oddities which can confuse anyone used to working on modern bikes.