Bicycle Mechanics - Dia Compe 986 cantilever help

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Schwinnrider
07-17-11, 07:39 PM
I recently bought a cheap front mini rack on eBay, and attempted to mount it today. I took the cantilever brakes off(Dia Compe 986 on my '93 Bridgestone XO-2). Turns out the holes on the rack struts are too small to fit over the cantilever posts, so I'm going to have to borrow a drill and ream them out. I put the cantilevers back on and now they're way out of adjustment and are rubbing. Sheldon Brown covered this brake a bit on his website, but the instructions aren't clear. Anyone know a good online walkthrough on Dia Compe cantilevers?

FBinNY
07-17-11, 08:03 PM
It's been a while, so disregard this if it doesn't seem to match your brake. If I remember correctly 986 brakes used the same spring balancing system as the Sun Tours I'm still riding.

On side the spring engages a hole in the boss like any other brake. On the other the back of the brake is a large flat nut which is one piece with the bushing the brake pivots on. The springs leg goes into this nut, then is mounted on the post. Tightening the outer mounting bolt jams the nut so it can't turn. Once the brake is basically set up ease of the mounting bolt slightly and use a cone wrench (my Sun Tours take a 19mm) to rotate the block until the springs balance and the brake is centered. Then tighten the mounting bolt to keep it there.

BTW- it's important that the pivots are properly lubricated with oil, otherwise the arms are sticky and it won't keep the perfect adjustment. Also I have a bunch of cone wrenches for this, PM me if you need one.

Again, disregard the above if you don't have the flat nut in the back of one side.
dsbrantjr
07-17-11, 08:14 PM
Schwinnrider: Check the instructions for mounting your rack; I believe it is supposed to mount to the front of the cantilever brake bosses in front of the brakes, not go over them in place of the brakes. So check before you drill. Here's an example of how they mount: http://store.velo-orange.com/index.php/accessories/racks-decaleurs/racks/gran-compe-ene-mini-rack.html

Here's an overview of adjusting cantilever brakes: http://www.sheldonbrown.com/canti-trad.html

Edit: Here is the special hardware used to mount the rack to the cantilever bosses, if it isn't included with your rack: http://store.velo-orange.com/index.php/accessories/racks-decaleurs/racks/canti-brake-rack-mounting-bolts.html