brakes on a non-braking rim....

[lordjenks]

so i have just bought a second hand bianchi pista and it has veloctiy b43 rims on which have no braking surface... so my question.... if i were to put a front brake on what would happen, would it crack all the paint or would the paint slowly just wear away, also could you recomment a half decent front brake, i only have about 20-25 to play with so....
thanks guys

 

[mickle]

It's a heavy duty road rim, available in drillings up to 48 and built to cope with stunt riding. The paint will simply wear off.

 

[MartinC]

A good quality rim with a braking surface will have:
- parallel brsking surfaces so the the brake pads can be aligned properly
- milled surfaces for even braking
- a decent thickness of metal where the pads bite to stop them wearing away and allow a wear marker that will show when the rim walls have worn too thin.

A rim with no braking surface won't have any of these. The B43 doesn't seem to from the pictures I've seen - it appears to derive it's strength from the depth of the rim section and the transverse bracing not from the thickness of the walls. When a rim is worn too far it the tyre pressure can detach a sharp section of the rim circumference - both the loose shard of metal and the tyre blowing off the rim are potential hazards.

Using brakes on a rim not designed for rim brakes isn't a generally a good idea. The paint isn't much of an issue - it may provide a frictionless surface for the pads which will stop the rims wearing (and the brake working) or it may just wear off. If it's anodised not painted then it should make the rim surface harder - for a little while until it wears off.

 

[accountantpete]

I'd also be a bit concerned about heat build up especially on a long steep descent - you don't want your inner tube popping.

 

[mickle]

Eh?? Eh?? Honestly, just stick a brake on it, it'll be fine.

 

[alecstilleyedye]

i'd use a soft compound brake pad. you'll wear them out quite quickly, but better than wear out the rim.

a pair of £2 blocks from lbs are used on the 1960s sprint rims on my old fixed; not only do they look the part, they don't damage the rim at all in the dry.

 

[Sheffield_Tiger]

Forget riim brakes, go for the "sneaker brake"

Go on, we've all done it as kids..