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My understanding is that it’s important to regularly test one’s brakes, by grabbing the lever and squeezing it hard, perhaps all the way down to the bars. The theory is that if they’re going to fail, it’s far better that they do so on the workstand than during a panic stop.

My question: does this testing itself cause wear or damage? And if so, how can I mitigate or compensate for it?

To clarify: This test is designed to see if anything is broken, not tightened sufficiently, etc., rather than “do the brakes stop the bike”. For example, this weekend I discovered that the cable had worn down over a corner [aside: I have an appointment to re-route the cable] by breaking it during this test.

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Testing by riding and stopping suddenly of course adds wear, just like "normal" braking. So long as you don't overdo to the point of overheating the brakes, and so long as you don't get into the habit of "testing" your brakes every 30 minutes, should add negligibly to the overall wear. Testing by just squeezing while the bike is stopped adds only miniscule wear to cables and pivots, but also proves very little. –  Daniel R Hicks Jul 15 '12 at 18:48
    
The exact answer is "yes", but that is why you are testing. If something is going to break the next time you brake hard, you want that to be when you're stationary rather than when you're doing an emergency stop. What you are most likely to break is a cable that has frayed to the point where it's dangerous but not broken. Happened to me at a traffic light the other day, I was idly squeezing the brakes and track standing when the rear brake cable snapped. It was mildly annoying, so I just stopped at the LBS 1km later and bought a new one to fit when I got home. –  Kohi Jul 15 '12 at 23:51
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Frankly, if you let a brake cable get frayed to the point that it broke, you're not paying enough attention to regular maintenance. –  Daniel R Hicks Jul 16 '12 at 0:47
    
@Daniel: Oh. I didn't realize that. –  Reid Jul 16 '12 at 4:05
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3 Answers 3

First of all, if you can squeeze it all the way down to the bars, your brakes are probably not set up correctly.

When braking, there is a point where squeezing too hard will not get you any benefit, and will only destabilize you instead. So, it's important to test the brakes while moving (slowly, e.g. 3 km/h, to be safe). And so, as you discover the point where there is no point in squeezing harder, your testing will not put too much wear on the brakes (that is, no more than regular use).

As a side note, testing the rear brake will probably involve locking your rear wheel while moving, and that will wear the tire alittle. I guess this is more significant than the wear you cause to your brakes (cables, pads, etc).

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Sometimes I can take them all the way to the bars, sometimes not. It’s very hard to do so. They are cantilever brakes (non-V-brakes). The wheel is true within a couple of mm, and the pads ride just a hair away from rubbing with very modest toe-in. I don’t think they’re set up wrong. –  Reid Jul 15 '12 at 20:48
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As others have noted, your brakes probably aren't set up correctly if you can squeeze the lever so far that it touches the bar while the bike is stationary. That said, squeezing the brake levers while the bike is on a stand won't cause any more wear than normal braking would [1].

If you want to determine how hard to squeeze the brakes while on the stand, a good test is this: ride at a moderate speed in a safe environment and then try to rapidly stop. Your brake levers should not touch the bars, and (obviously) nothing should break loose. A properly adjusted rear brake should be able to skid the rear wheel (but it is considered poor braking technique to skid the rear wheel). A properly adjusted front brake should should be able to lift the rear wheel off the ground (you don't want to actually lift it, so use care). Try to get a feel for how much pressure you apply to the levers when you practice a panic stop and then apply a little more when the bike is on a stand.

Please note that it is unsafe to suddenly fully-apply the brakes (suddenly squeeze both levers as hard as you can) while traveling at speed. If your brakes are properly adjusted, you should be able to easily lock either wheel by pulling hard on the brake lever.

For the rear wheel this is less of a problem: You will simply skid the wheel, wearing down the tire. If you do this enough, or at a high enough speed or with a thin road tire, you risk wearing down the rubber to the innertube. If that happens, the tire will rapidly deflate and you will be riding on the rim (this is bad).

Locking the front wheel is a bigger problem: the front wheel will NOT skid. If you lock the front wheel, you will go over the bars and hurt yourself.

[1] Within reason, of course. If you're some sort of Olympic weightlifter, it's possible that you might squeeze hard enough to damage something. Also, if the brakes are "looser" after you squeeze really hard (ie, if you have to pull the lever farther, not harder, to make the brake pads touch the rim) then you are either squeezing too hard, or you need to readjust the cable and tighten the cable clamp on the brake.

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From the principle that the brakes are designed to brake, and that "braking" means locking the wheel with a rider on the bike, I think that is the proper way to test the brakes: on a safe place, get the bike to a not-too-high speed and grab the brakes fully.

That should do no harm PROVIDED the brakes are setup properly. For example, I had a bent bolt in a dual-caliper road brake (the bolt that attaches the brake to the fork) because there was a small play - the screw and nuts were not properly tightened.

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