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September 22, 2007
Fourth time's a charm
I climbed aboard the Mighty Schwinn a short while ago and took it out for the first ride since I had the most recent broken spoke replaced. My thought yesterday was that I'd put 50 miles on it today. I modified that thought when it occurred to me that I've been breaking spokes lately and that I lacked the type of rear-wheel confidence a person needs for longer rides.
So, I opted for a 15-miler instead. Which I shortened to 12 when at 8.5 I broke a spoke.
I know, without a doubt, when it happened. I was approaching a light I knew was about to change to green and I wanted to be close enough to it when it changed to make it through (I obey the traffic laws when I bike). When I bore down on my right pedal to accelerate I heard the tinking noise that suggested something had broken; a glance down at the now-wobbly rear tire verified it was a spoke.
This is four spokes on the new rear wheel and I've been breaking a spoke almost each time I go out for a spin.
I'd thought the breaking of the spokes had something to do with my body weight (I'm 233 pounds) though the old wheel never had trouble with my weight and I weighed more than I do now for a lot of the time I rode around on that one.
The last time I picked the bike up from the shop the tech suggested that taller guys might break more spokes than the less tall. I wasn't sure what he was getting at even when he mentioned torque and I thought he was just trying to be polite and unwilling to say "well, you weigh a lot."
This last week one of the engineers at work said something about spokes breaking that shed some light on this and made some sense. It isn't the weight pushing down on the tire that causes spokes to break it's the force applied to the spokes by the the rear gears (and, therefore, the chain and the crank.)
While I'd like to think I have super powerful manly-man legs and that I'm capable of chirping The Mighty Schwinn's rear tire in all 12 gears I'm more inclined to believe the new wheel was assembled with crappy spokes.
In any case, it looks like I'll be guying a new rear wheel.
[By the way, the engineer at work said something that made a lot of sense. If I've explained it in a way that sounds sort of stupid, well, the stupidity is all mine.]
Posted by delmer at September 22, 2007 8:38 PM
Comments
Going to town on the cranks puts a lot of torque stress on the rear hub. You need to get a better rear wheel. Or have the entire rear wheel relaced with quality spokes. I have broken two spokes in 10 years but that's all, you only have two inches on me and we weigh similar.
Get this......http://tinyurl.com/yrp225
Posted by: mikeo at September 22, 2007 10:44 PM
I think whoever built your wheel over-tensioned the spokes and/or used inferior-quality spokes. A good wheelbuilder checks the spokes with a tensionometer to avoid over-tensioning.
Posted by: Bill at September 23, 2007 3:06 AM
I support Bill in his comment. Your technician probably just put in one spoke and did not check the tension on all spokes, thus causing the next break.
Posted by: Jack at September 23, 2007 11:28 AM
I'm inclined to think the spokes are substandard. After the first break the tech told me he'd checked the tension of the other spokes, and I've no reason to doubt him.
This is a wheel the bike shop got pre-made. They didn't build it themselves.
Posted by: delmer at September 24, 2007 2:49 PM