Nov 7, 2010


Earlier this week as I was leaving the office, I noticed that I had lost another bolt from my crank. This has been a bad year for chainwheel bolts for me. That's like... the 4th one I've had fall off a bike this season. While contemplating this most recent loss and tightening down the 4 bolts the remained, I also noticed that my chainwheel had gone from a 42-tooth to a 41-tooth somewhere along the way - one tooth was entirely gone and the others were pretty worn.

I picked up an Origin8 replacement chainwheel and some new bolts, popped the crank off and replaced the chainwheel this afternoon. I was quick and simple, but definitely necessary. I inspected the rear cog and that was just fine, with very little wear. The chainwheel that was on there was very cheaply made - it was probably the original wheel and seemed like it was just heavy stamped steel. The cog, on the other hand, was a newer Shimano cog, so that was in much better shape.

I probably took a little life off the chain by riding the chainwheel in that condition, but measuring it, it's not too bad, and with winter coming on I am not going to deal with that until Spring (hopefully).

I learned today that Park no longer manufactures the nifty caliper for measuring bolt diameters to replace these components. The best solution is apparently to consult Sheldon Brown to calculate your bolt diameter.

I find being able to do these kind of simple repairs to be very empowering.

Unseasonably warm temps brought us outside today for an afternoon ride with that little chore out of the way. We stopped at the Midtown Freewheel and got Molly outfitted with some full-finger gloves, a flasher and a head-band type ear warmer. She's kept riding as the weather has gotten colder, so she's earned a little investment in gear to keep her comfortable in the chilly. She'll be rocking a rechargeable Blackburn Flea rear flasher around the neighborhood effective tomorrow. I like these - they are small, bright, and last a long time between charges. I have yet to run one in really cold weather, but I suspect it will be just fine.


  1. I think this is totally bizarre that you keep busting chainring bolts. I have entirely the opposite problem. I can never seem to get mine off no matter how hard I try.

  2. Agreed - I have never seen this before. All I can think is that they were poorly installed the first time. The first time this happened it was on the Rawland, which was a new ground-up build. It may be that the mechanic simply forgot to tighten them when he assembled the components and I never caught it. This time, it was on a single speed conversion that I bought used. These bolts I did check mid-summer and found them to be tight. The chainwheel was poor quality and may have been flexing or something, I suppose. The bolts that remained were torqued down well and took some force to release. Very mysterious. I am coming to think I have gremlins in my garage.