Disc brake catastrophe–Or, failure is the root of all learning

Okay, “catastrophe” might be a little strong. More like “potentially very bad situation.” Regardless, it has to do with my new(ish) Soma bike, which you may recall has disc brakes.

Disc brakes are a new system to me. If they’re not familiar to you either, they look like this:

avid bb7 road disc brakes

The rotor–that circular metal disc–is attached to the hub of the wheel, and the brake itself is attached to the fork (in that picture, it’s the black thing that’s sort of hidden behind the black fender attachment). When you brake, two pads in the brake on the frame squeeze together against the rotor and you stop. (I think this is basically how brakes in a car work too?)

Anyway, it’s all very nifty because since you’re not rubbing against the rims of your wheel to slow yourself down, your wheel lasts longer (unless you destroy it through means other than wearing out the rim;). And they gather a lot less gunk in wet weather, which means that when it’s raining and you brake, your bike still actually stops. Also, if your wheel comes out of true, you can still ride just fine, relatively, since the brake is on the hub and the wonkiness of your wheel won’t affect it the way it would rim brakes.

So I’ve been pretty psyched on my disc brakes.

The braking power in my front brake has been gradually declining, and I’ve been gradually tightening it, but the other day I decided that for realz I needed to actually replace the pads. I had a general idea of how to do it, but since it’s a whole new system to me I wasn’t sure about the finessing details. So I watched some YouTube videos, and talked to one of the mechanics at Seven Corners Cycles when I bought a new set of pads from him. Feeling cocky, I took out my old pads and put in new ones.

avid bb7 road disc brakes2(the copper-colored tabs that stick out of the brake are the arms to the brake pads. They sit super tucked away inside the brake)

Great! Pads replaced! Commence the better braking! Except that I did it wrong, and as I was biking home from work on Monday, I hit a bump while I was braking down a hill. With a hideous ping, one of the brake pads shot out, hit the spokes, and wet careening off into the road. Yikes! I stopped as best I could with only my back brake (only about 20-30% of your stopping power comes from that one), pulled over, and gathered up my errant pad.

Luckily I was actually able to find it. And since I knew I’d done it wrong the first time, I tried again, differently, to put the two pads back in together. Tighter this time.

But sure enough, another hill, another bump, and the same brake pad went flying off my bike again–except this time it flew into traffic and promptly got run over by a car. So much for my mechanical skills.

To make a long story short, I was only a few blocks away from The Bike Gallery, which was still open for another 20 minutes. I stopped in to buy new brake pads again but mostly to ask if one of their mechanics would mind walking me through what I was doing wrong. Sure enough, a super awesome fellow (thanks, Nathan!) walked me through exactly what I should have done–and unlike the first time, when I hadn’t yet tried it myself, this time I could identify my personal mechanical pitfalls. (Mostly, it came down to not pushing hard enough. Disc brakes are burly.)

So there you go. It was a good reminder to me that sometimes near-catastrophic failure is necessary to show you exactly what you’re doing wrong. I’m pretty sure that when I go to replace my back brake pads in the near future, I’ll be able to do it right:) I hope:)

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