 |
 |
Rites of Spring 2005 / rites042BANG! Fortunately we were on a straight, level, and smooth portion of the Springwater corridor when this happened. The sidewall of the rim split over a 10" long piece. Had we been riding one of the fast downhill sections, I'd probably be picking gravel out of road rash right now. At it is, I walked about 1½ miles to get to downtown Gresham. Fortunately, my wife had waited for me at Jazzy Bagels, and I asked her to ride home and fetch the van- this wasn't something I could fix on the road. Even more fortunately, Jazzy Bagels had a fireplace I could sit next to, coffee to warm my insides, and live music to keep me entertained. (If it had been just me on my own, I could have gotten a replacement wheel from the bike shop a couple blocks away. But I like building wheels.) That's how the Rites of Spring ended for me this year- the first ride I've failed to complete in several years. Too bad. Rim post-mortem: I knew the rim sidewalls were getting thin. The brake tracks had acquired a concave shape that worried me. However, I thought I'd have more warning before the rim let go completely. The rim was fine when I was cleaning the bike this week, and showed no distortions when I started to ride to Gateway this morning. It was only after we'd started along the path that I started feeling a slight pulsing in the brake- which I thought might have been a slop of oil on the rim. Beyond that, I had no warning: just BANG! and I was riding on the rim. Jeff Wills |
|
|
Post-mortem postscript: Here's a couple images taken after I removed and replaced the rim. I can't recall if the entire section blew off at once, or if it blew off at the folded corner and then peeled the rest off as I walked the last mile before my pick-up point. I don't have a micrometer, so my best guess is that the thin portion is 0.7mm thick.
This is a Sun CR-18 rim. After I built it, it's never needed more than a slight touch-up truing. It's seen several thousand miles, including winter commuting, two Cycle Oregons and one Oregon Bicycle Ride. I guess I'm a pretty good wheelbuilder. The replacement is a Mavic A719 rim, silver, with a deep center well (hurray!), welded seam, and machined sidewall (boo!). I'll keep a closer watch on the sidewall- but it should last a little while at least.
