Panicked by hanging chad
About half-way home last night, I hit my brakes for a stop sign and immediately felt the front brake grab hard and make an awful clattering noise on every revolution of the wheel. What the heck is going on? By rotating the tire with the brake lever slightly pressed, I could tell I had an issue of some kind but in the darkness I couldn’t see what it was.
I gingerly rode up to the next available street light and took a look. With my old eyes in the dim light, I couldn’t make out the extent of the damage, but I could see and feel what was definitely a pretty good sized burr of metal sticking out of the groove milled in the side of the rim. At this point I still wasn’t sure what was going on. Did I have a rim that was cracking? Surely not…this bike is less than a month old and has a little less than 300 miles on it. Was it safe to ride on home, or should I call for a ride? Lacking any further information, I decided to pedal homeward and just try to avoid using the front brake (which, by the way, isn’t necessarily an easy thing to do when riding in traffic). In hindsight, I could have answered all those questions if I had thought of taking one of my headlights off and using it as a flashlight. Doh!
After I pulled into the garage and got the lights on, I could see that the groove in the rim had what I can only term as a “hanging chad”. There was about an 1/8th of an inch where the rim material wasn’t completely milled out. It had pulled up at the front end and was catching the brake pad as it passed by. I grabbed a pick out of my tool box and quickly pulled it the rest of the way out. It probably would have come out on it’s own if I had used the brakes more. After inspecting the brake pad to ensure it hadn’t been badly damaged, I concluded that the problem was solved.
If you look closely, you can see where the burr pulled off in the middle of the rim just to the right of the spoke nipple.
I do have one remaining question, however. What is the point of that groove in the middle of the rim? I suspect it must be designed to channel water off the brake pads, but I’m not sure. My road bike doesn’t have that. Anybody know?
God bless….
TW
Tags: bicycle, Bike Commute, Bike Wheel, Cycling, Fitness
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December 16, 2009 at 2:34 pm
I believe it’s called a wear groove, analagous to the holes machined into rims. When the brake pads wear the rim to the point the groove or hole is no longer visible the rim needs to be replaced. If you want those rims to last get some softer brake pads like Kool Stops. But get the kind that don’t squeal and wide ones because of the groove. Think of the groove as a way for the manufacturer to sell you a pre-worn rim.
December 16, 2009 at 2:57 pm
In addition, pull off your brake pads and look for melted aluminum imbedded in the pad. Some pads generate enough heat to melt aluminum, causing aluminum to be imbedded in the pad, and subsequently, excessive rim wear. It does look like there is something in your brake pad wearing grooves in the rim.
December 16, 2009 at 6:12 pm
I agree with Garrison’s first comment. Wear ring get out the Simple Green & a lot of the coloring will come off and the rim color will look more even. BTW, I’mreassured to not ne the only one riding around in the dark with old eyes.