Sunday, September 14, 2008

Disc Brakes vs. Rim Brakes


The links below provide results of brake testing conducted by the German magazine Mountain Bike. They wanted to see how rim brakes and disc brakes compared when faced with the high temperatures of a simulated steep mountain descent. Of note most disc brakes did not perform as well as a rim brake with cloth rim tape and a standard tube. Although many of the disc brakes systems are out of date newer models are not built any more robustly and in fact many may actualy be less resistant to heat as lighter and lighter brakes are designed.

2000 Testing

2001 Testing [incl Avid BB7s]


This isn't to say disc brakes aren't a good idea for some applications [winter riding, muddy mtn biking, wet commuting], but they are not immune to overheating and failing on long descents. As such you need to manage the heat load you put into disc brakes just like you would a rim brake. Although disc brake failure won't result in a tire blow out in many cases the damage to the disc brake is permanent and the brake will no longer function - not great on long tour or miles from nowhere in the back country.

3 comments:

Anonymous said...

"Disc brakes fail as plastic parts melt". Just what plastic parts are being referred to? There are none on my Avids. Well, I guess there is the plastic on the metal wound cable housing to keep the rain out. Yet, if I took a match to them and set them on fire, my disc brakes would still work fine even with the plastic burning. It is clear that the whole "test" was biased against disc brakes from the start. Just don't try to take mine back as I don't want to return to rim brake heat induced blowouts and dragging my feet on the road to stop in the wet at the stop sign at the bottom of a steep hill.

Vik said...

All 3 pairs of my Avid BB7 disc brakes [the ones tested in the article] have plastic parts - such as the adjusters that move the pads in and out.

I'd be happy to read/post more over heating test data, but nobody else has published that sort of data.

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