Joe Minton

Motorcycles have had disc brakes for more than 40 years. They are reliable and simple in practice. There are millions of them and many, many millions more cars fitted with hydraulic discs. Hydraulic disc brakes have proven themselves in very many ways and are the standard for practical use.

Bicycle discs have been long in coming but they are here and they will prevail.

Automotive disc brakes are about the weight of the old drums were, perhaps a bit lighter but no one cares very much. After all, the things weigh a ton-and-a-half anyway, and -- all one has to do is push on the throttle to make-up for any miniscule weight increase. You know: --- car engines make Horsepower we make Watts ;o)
Bicycle disc brakes are mostly heavier than rim brakes. Weight is more of an issue with bikes. However, even that concern is diminishing.

Automotive and motorcycle hydraulic systems seldom or rarely need bleeding. Most are never bled and yet they remain reliable. If bicycle hydraulics need bleeding in use, then, there is something wrong that needs to be addressed.

There must be no air in the system, including the reservoir. Motorcycle brake systems accomplish this by fitting a sealed bellows under the cap of the reservoir so that the entire system can remain air-free. Like with motorcycles, one must be able to invert a bicycle without introducing air into the brake master cylinder, lines or calipers. There is no excuse, at any level, for things being otherwise.

Joe