Bicycle Mechanics - mechanics

my back brake seems to lock on when it is pulled fairly hard, especially when keeping brake on for a longer time. i am using alloy rims and centre pull brakes the brake blocks are ordinary type and the rim is free of contamination. any idea why this should happen:confused: [COLOR=firebrick][QUOTE]let the wheel of life go on round and the non pollutant blossom[FONT=times new roman][SIZE=3]

Center pull brakes? How old is your bike? 1970's or maybe 1980's? Nothing wrong with an older bike, but it will help us understand the situation.

I guess that your brake mounting is loose allowing the brake to deflect in toward the front of the bike. Look at the mounting bolt that is located on the side TOWARD THE FRONT OF THE BIKE. Make sure it is tight.

Otherwise, you brake mechanism might be dirty, neat lubrication, OR, it might need replacement.

If you do need to replace the brakes and you have an older bike, switch to side-pull brakes instead of center pulls.

thanks mike i willgo and check the advice out that sounds as though it maybe right. the bike is a claud butler majestic, i think it was made in 1983. asyou have pointed out side pull have a more graduated stop:beer:

Originally posted by briger
thanks mike i willgo and check the advice out that sounds as though it maybe right. the bike is a claud butler majestic, i think it was made in 1983. asyou have pointed out side pull have a more graduated stop:beer:

Well, I don't know about side-pull brakes having a more graduated stop, but they are more positive, easier to maintain, and less trouble.

Just out of curiosity, has you bike been sitting around unused for a long period of time? Brakes can get sticky when a bike sits around. The gunk in the brake arms hardens, the brake parts oxydize and the cables rust in the housings. All of these things can contribute to the phenominon you described.

You would be amazed at how much the cables can rust inside the housings. I just worked on a bike yesterday. It took all my strength to remove the cable from the housing because the two had been rust-welded together. I wondered how the brakes could function at all under those conditions.

Your next step might be to replace the cables, clean and lubricate the brake arms.

got any lumps on your rim?

funny you should talk about the bike lying around, it gets used fairly frequently but the storage area is abit on the damp side, it lies against an old stone wall. as for the brake cables I renewed the inner and the outer recently and renewed the brake blocks. I followed your advice and lubed the brakes moving parts also tried squaring the centering of the brake calliper and I think it is not causing the wheel to jam up but will keep an eye on this and may move over to side pull if I have more trouble

thanks pat will check for any bumps on the rim thats another good point