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Avid BB5 Caliper Damage

Damage to the rear Avid BB5 disc brake caliper after the top mounting screw of the caliper bracket came out while starting to descend The Rollercoaster at Stony Creek on 16-May-2008. This damage does not affect use of the brake at all.

Just after starting to descend The Rollercoaster at Stony Creek (a windy, narrow, fun descent from the highest point in Macomb County) I applied my rear brake and started to hear a tremendous houl from my rear brake and found myself slowing very quickly. I was able to finish stopping with my front brake, just as someone behind me asked if I was all right, and what the sound was.

A quick check showed that the upper bolt on the bracket which connects the caliper to the frame itself had come off and that in squeezing the rotor the caliper had rotated forward and lodged itself against the disk, slightly stuck between the frame and the disc. Walking about 15′ back up the trail I found the screw, I was able to partially put it back in by hand. Because of the length of the tool I couldn’t fit it between the rear rack and screw head, but thankfully the person who had stopped had a much shorter wrench and I was able to tighten things back up. A quick readjustment of the brake and I was on my way, with the brake actually working better than it had previously.

I’m not really sure how the screw came out. It was tight the last time I checked it (a few weeks ago), and it had thread locking compound on it. I do wonder if the combination of the rear frame, the slightly ratting bag, and the rough trails contributed to the bolt loosening.

Today I headed back out to Stony Creek with the frame removed and with only a multi-tool and my keys. While I didn’t like riding without the ability to fix a flat, I accepted the risk of a five mile walk until I can sort out the CamelBak Question. Things went well, and it seemed like it was a generally a quicker ride with the lighter bike, except it seemed like I had a much harder time getting up some of the steeper / longer hills (generally in the two-track area) because I kept spinning the rear tire. Twice I just stopped part-way up and walked. It was a much quieter / pleasant ride, although I do think I’ll get (or fashion) a soft chainstay guard to cut down on the loud chainslap.

Now it’s time to shower, eat something, and poke a bit with Ivan’s P3. I received new firmware, but it still doesn’t seem to be working, so I’m going to write a little test software for the PICs and be sure they are working right.

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