The 40,000-mile chainring

I have been enjoying the heck out of my newly rebuilt LOOK KG486. There is nothing like a “new bike” to re-motivate (actually, the frame is 10 years old and most of the components only one year younger)—in the five weeks since I picked it up from the shop I’ve logged just over 1,000 miles on it despite it being the dead of winter! I don’t think I’ve never been as ga-ga over a 10-year old bike. From the beginning, however, I noticed trouble with the drivetrain. I already knew the chain was worn, and since I would need to replace it I also decided that a new cassette was in order—something with gears more suitable for flatland terrain rather than the old Shimano 105 12-27t cassette I had gotten for my latest trip to France and had slapped on when the previous cassette had worn out. I ordered up the chain, paired it with a 12-23t cassette (both Ultegra—no sense in paying top dollar for expensive Dura Ace components that will only wear away), and anxiously awaited their arrival. In a few days, I had them on the bike, hit the road to enjoy my new lease on a crisply functioning drivetrain, and CRUNCH!!! I hadn’t even thought about the chainring also being worn, but when I looked closely its teeth looked suspiciously small. The next several days confirmed the problem—no chain slip in the small chainring no matter how heavy the load, but whenever I was in the big chainring I had to really take it easy, or else CRUNCH!!! I ordered up the new chainring (and a small one as well, no sense in mixing old and new), and when they arrived I took of the old and this is what I found—teeth worn to nubs! I guess I can’t complain, since I probably logged around 40,000 miles on this chainring (for what it cost to buy a new one, that works out to about 1/5¢ per mile).

After 10 years and 40,000 miles, the teeth on this chainring are little more than nubs.

After 10 years and 40,000 miles, the teeth on this chainring are little more than nubs.

I had a bit of a scare when I was taking off the chainrings. The first four bolts came off fine, but the fifth just spun around as I turned the hex wrench—the nut spinning freely along with it. Now, it’s been a long time since I’ve changed a chainring, so I had forgotten what to do when this happens. I jumped on Google, looked it up, and found out that I needed a chainring wrench to hold the nut in place while I unscrewed the bolt. Great—now I have to wait until tomorrow, go to the bike shop, and buy a chainring wrench before I can ride again. I decided to go out to the toolbox and look for something… anything… that might serve as a chainring wrench in a pinch. As I was fumbling through the toolbox, what do you think I found? A chainring wrench! I don’t remember ever buying it, but I was sure glad I did. That problem solved, it was a quick matter to remove the last bolt, switch out the new chainrings, and voila… a “new” bike with brand new chain, chainrings, and cassette. Check out the teeth on the new chainring below!

The teeth on this brand new chainring will give fresh bite to my stroke.

The teeth on this brand new chainring will give fresh bite to my stroke.

© Ted C. MacRae 2015

About Ted C. MacRae

Ted C. MacRae is a research entomologist by vocation and beetle taxonomist by avocation. Areas of expertise in the latter include worldwide jewel beetles (Buprestidae) and North American longhorned beetles (Cerambycidae). More recent work has focused on North American tiger beetles (Cicindelidae) and their distribution, ecology, and conservation.
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