Tuesday, August 05, 2008

Bicycle Maintenance

I have always feared the words: "mechanic owned."  It is one of those things that people boast about when trying to sell something.  Well, I'm a believer that what this really means is that any form of maintenance has been neglected until the last conceivable moment. Same sort of principle in play when you see the nurses and doctors outside of the hospital or clinic smoking.  I believe the rationale is that "I'll fix it later."

Having been professionally (under-)employed at a bike shop for more than a decade, and earning my certificate of completion from the Barnett Bicycle Institute, I consider myself a pretty-good mechanic.  From this personal experience, I can tell you that there are bikes that I own that "neglect" is the only form of maintenance.  Chief among these would be my Quickbeam commuter.

I had spun by Hiawatha Cyclery to pick up the part for my fender that I broke sometime better than a week ago.  When I got home last night I took after the bike with a bucket of hot soapy water and a scrub brush.  I had to resort to using acetone to remove much of the congealed grease from months of abuse.  (The last time I did any form of cleaning was in April.)  It was time to remount the fenders and lights since it is dark in the mornings when I leave.  For the last month-plus the rear wheel has had an awful vibration to it when braking.  I figured that I had dented the rim or something somewhere along the line and I would do my best to fix it.

Said a few colorful words and remounted the fenders (having misplaced much of my original hardware.)  Before going much further, I test-fit my rear wheel to see if my tires were going to clear the fenders.  Clearance was worse than I had recalled, but the tires were not very consistent in width.  Running out of patience, I decided that I would see what I could do about truing up the rear wheel.

I found that the wheel was nearly perfectly true, but there was significant wobbling of the sides of the rim?  Both sides of the sidewalls were striking the calipers on the truing stand!?  I stopped the wheel in the stand and inspected for dents.  No luck.  I dismounted the tire and put the wheel back in stand and found now that the wheel was both true, round, and no variation in sidewalls?

I removed the rim tape to find that the center of the rim is cracked, almost all the way around the wheel.  When the tire is mounted, it seems that the air pressure is enough to force the crack to open up.





This wheel was built in March with a Velocity Dyad rim.  It has only lasted about 4,000 miles.  Wondering what's the deal?  Combination of the rigors of commuting, carrying a lot of weight, wide tires, neglect?  

4 comments:

Jim Thill said...

I used to think your brother S. was hard on bike parts.

Pete said...

d) all of the above?

rigtenzin said...

That's a nice photo. It contains an illusion, sort of. It looks like a tubular rim with no "hooks" even though it's not.

I like photos of broken bike parts. When I remember, I post them on my blog too.

-d said...

J.B. Weld. You will get another 4000 out of it easy.

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