Technical FAQ: Durability of disc brake pads

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Dear Lennard,

I’m moving up to disc brakes and was surprised to read they have a short life span. Most searches give me 500-1200 miles, depending on material. I asked a friend who uses these who replied that this is nuts, as he gets 3,000-plus miles.

What is your sense?

– Jeff

Dear Jeff,

In general, I agree with your friend. I generally easily get 3,000 or more miles out of organic pads, and sintered pads last a lot longer. However, it completely depends on the weight of the rider, the terrain being ridden, the weather conditions when riding, and the road or trail surface. In some conditions and under some riders, pad wear can be way faster than the rates you quoted.

For instance, I have a very big, strong customer goes through pads very fast. He has bought a dozen titanium custom road bikes from me over the years and rides them a lot all over the world. His weight has fluctuated over the years between 300 and 350 pounds (135-160 kg), and he has undertaken many multi-week cycling trips in the Pyrenees and Alps. With Shimano organic pads and 160mm rotors, he was going through a set of pads every day on those trips! With sintered pads, he was generally able to get an entire week in the Alps out of a set of pads.

To envision this, I had to recognize that he and his bike weigh the same as me, my wife, and our tandem together. When we go downhill on our tandem, we pick up speed incredibly fast and have to do a lot of hard braking on serpentine mountain descents. We, too, would go through a lot of pads if we were to do four- or five-pass rides on it day after day in, say, the Dolomites.

Another example of high pad wear is when riding technical terrain in really light, wet mud or wet snow. For the former, I recall the Thursday and Friday races of the 2013 US Cyclocross National Championships in Verona (Madison), WI, when disc brakes were just starting to arrive in cyclocross and were not hydraulic. Deep snow had fallen two days prior and above-freezing temperatures combined with so many riders churning over the course turned it into thin, light mud.

Normally, disc brakes have a big advantage in mud over cantilever brakes; sticky mud collects around the rims and cantilever brake pads (as happened on the Saturday races in warmer temperatures at this same Nationals) while being thrown away from disc-brake rotors. On the Thursday and Friday of that January Nationals, though (I raced that Thursday in 55-59, with cantilever brakes), riders with cantilever brakes didn’t necessarily have to pit (I didn’t). However, riders with disc brakes were having to switch bikes (or pit for service if they didn’t have a second bike) every lap or two, because their brakes didn’t work anymore. They had to get their brake cables tightened multiple times during the race and their brake pads replaced at least once. I wrote this article about it.

Another time I remember being at an early-season NORBA National MTB race at Big Bear, California when the mountain was covered with snow. Downhillers in the event were going through disc-brake pads every run (maybe two miles).

For road riding in dry conditions on rolling and flat terrain and a rider under 180 pounds, however, pad wear can be very long, perhaps 5,000 miles with organic pads and more with sintered pads.

― Lennard

Dear Lennard,

The late Jobst Brandt claimed that going down a hill slowly caused more rim heating than going fast, since more of the energy was dissipated heating the wheels, and less by wind resistance.

As usual, he is very certain, but you seemed to imply that cautious descending would lower the risk. (And no doubt, it lowers other closely-related risks like sliding out or missing a turn.) You had a long and thoughtful discussion of an incident in a neutralized descent at the Tour of Oman (where admittedly, it was beastly hot) a few years ago.

I am not going to descend at 60 MPH because Mr. Brandt says it makes my tires safer; I am just curious what you think.

– Jon Blum

Dear Jon,

I agree with Jobst in the sense that higher relative wind speeds will cool the brakes better. The question is, what to do when descending switchbacks. The method I use is to let the brakes go as much as possible between turns, to cool them, and then brake as hard as I need to (and no harder), just before the turns. This will result in lower average brake temperature than keeping the brakes on the entire time when descending.

― Lennard

Dear Lennard,

Should we believe the official weight and heights listed for riders in their team profiles? Some seem to be impossibly light for their height and I suspect riders rather have lighter weights listed, the same way basketball players want to be taller and football lineman as big as possible.

– Bruce

Dear Bruce,

I always take those with a grain of salt. Many times, I see it the other way around, though, especially for riders at the Tour de France, who have thinned down to the point of having bird arms and sunken cheeks. I have seen riders in pre-race bios listed at 145 pounds that can’t weigh more than 130 when they’re at the race.

Given that power-to-weight ratio largely dictates who has a chance to win the Tour, I can imagine that riders might exaggerate their weight in order to not be considered as seriously as a contender, and hence not be chased down as determinedly. Their threshold power might be estimated from time trial performances or found in Strava records, so sandbagging might be accomplished by overstating body weight.

Also, the few really tall pro riders seem to tend to downplay it. I don’t have a theory for why, other than, opposite of basketball players who want to intimidate with their height, they perhaps want to appear less out of the ordinary. When I was covering the Tour a lot (decades ago), I was 6’5” (I’ve lost more height since). There were a couple of riders whom I stood back-to-back with who were taller than I was yet whose bios listed them as 6’3” or 6’4”.

― Lennard

Lennard Zinn, our longtime technical writer, joined VeloNews in 1987. He is also a custom frame builder and purveyor of non-custom huge bikes , a former U.S. national team rider, co-author of “The Haywire Heart,” and author of many bicycle books including “Zinn and the Art of Road Bike Maintenance,” “DVD, as well as “Zinn and the Art of Triathlon Bikes” and “Zinn’s Cycling Primer: Maintenance Tips and Skill Building for Cyclists.”
He holds a bachelor’s in physics from Colorado College.

Follow @lennardzinn