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Chain hitting v-brake

A friend has a P-38 XT and the chain hits the front brake when he rides in the big chainring and the road is bumpy. Anyone else have this problem?

I have heard of some P-38 riders having chainline interference with REAR cantilever brakes, but not with front brakes.

The P-38 was originally designed way back in the early 1980s, before the mountain bike boom and the popularity of cantilever and (later) V-brakes. So road calipers were the original only option, and the tight clearances in the rear of the bike reflect this. With certain combinations of cantilever brakes and rear cassettes, and certain frame sizes, you can get an annoying rub of the chain over the top of the drive-side cantilever brake.

With the replacement of cantilever brakes by V-brakes (aka linear pull brakes) this problem may have been eliminated. I don't know, but have not heard of riders complaining in recent years.

I think your friend needs to take his bike to a competent mechanic who is recumbent-friendly and have his bike examined. Something is not quite right: could be a bottom bracket that is the wrong width, or a missing chain idler washer, or something else.

It is not the kind of problem that is easy to diagnose without eyeballing it though.

Safe riding,
Joel

1995 model with cantilever brakes. assembled it today and noticed some chain rub on the drive side brake. can it be converted to V brakes or is there some other way to eliminate this rub? if not maybe i'll try to make a cap of some kind to put over the brake attachment assembly

Yes, older cantilever brakes can be replaced with V-brakes. V-brakes are easier than cantilevers for ordinary mortals to set up properly and maintain in proper adjustment. They are cheap, give you room for fat tires and fenders, and work well in most situations.

Some V-brakes - like the old Odyssey A-brake - even allow you to route the cable from either side of the brake. There must be other V-brakes that let you do this too, and this can be useful on recumbent bikes.

Generally, V-brakes require longer cable pull from the levers than cantilevers. So if you keep the existing brake levers on your P-38 - which were intended for use with cantilevers - you may need to position your brake pads closer to the rims than you would ordinarily. If your rims are true, this should not cause problems.

Alternatively, you can get modern brake levers that have the longer cable pull. If you put an aluminum brake lever handle in a vise, heat it up with a torch, and give it a good whack with a mallet, you can get the bend that conforms to the Lightning drop handlebar.

Safe riding,
Joel

i like that! got a good smile out of it. glad about the V brakes. when i finally get to ride the bike i'll see how much rub there actually is. there is a rubbed place on the brake attachment point so with the few miles the bike has it must not be insignificant.

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