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BB7 mountain to road conversion

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BB7 mountain to road conversion

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flag fuzzhead45
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Posted: Feb 4, 2015 at 5:27 Quote
Hello everyone! I'd like to share some information that I wish I was able to find before I started this project. I had a set of 2012 BB7 mountain calipers lying around that I wanted to throw onto my cyclocross bike. Unfortunately the road levers on the bike did not draw enough cable to properly actuate the caliper. Researching online I found out that the BB7 mtn and road calipers are identical except for a different set of cams inside of the caliper body (see below) and that it might be possible to convert them using a road internals kit. I ordered the kit and got to it last night. Swapping out the cam on the moving piston was as easy as unscrewing the old one and putting the new one in its place. The second cam is press fit into the caliper body and needs to be pressed back out. I used a table vice and a socket to drive it out, and the same process to drive the new cam into place. I reassembled everything, threw it on the bike, and viola! perfectly functional, super strong brakes!

Here is the instructions I used to take apart the caliper body and torque arm assembly.
https://www.sram.com/sites/default/files/techdocs/service_manual_bb7__bb5.pdf

Also, note the differences in the ramp length in the two cams, the mountain version is much much smaller.

Press fit cam
photo

Piston cam
photo

There was also a lot of discussion online about possible differences in the torque arm length between the two models, I can confirm that the mountain version and the road version have the same torque arm length. Feel free to contact me if you need any help doing a similar conversion of your own!
flag fuzzhead45
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Posted: Feb 4, 2015 at 8:14 Quote
The internals kit was about 16$ off of Niagara cycles per caliper. Just google "BB7 road internals kit" and you will find them The torque arm can be mounted at different positions based on how you slide it onto the piston cam. Its a bit hard to describe, but basically the torque arm mounts to the hex bit of this piston
photo
This basically allows you to adjust the angle of the arm in 1/6th of a turn increments. (6 faces on the hex bit, 6 different positions). My guess would be that the road version shimano sells is just rotated 1/6th of a turn. I left mine at the mtn version angle and it seems to be functioning fine.

 


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