crusoe said:
Good advice! I didn't know about the front mounting vs rear mount caliper problem - that would present HUGE amounts of work to get it working correctly. I have looked at the mech disc brakes, but the census seems to be a lot less modulation and slightly less stopping power. Those reasons alone are making me shy away from mech brakes.
"Modulation" is a poorly defined term that basically means "feel". Feel doesn't stop you faster, and hydraulics only have one feel that can't be tuned. I got my first pair of hydraulic brakes in the early 90s when that implied Magura rim brakes, and I got my first Mountain Cycle Pro-Stop cable/hydraulic discs about the same time, so I've had a lot of time to get my head around what hydraulics and discs do and don't do. I started working as a bicycle mechanic in 1992, so I've gotten a pretty good overview since then.
Having had up to 450 pounds rolling on my normal pedal only bikes, and over 500 pounds on my e-bikes (and over 3200 pounds on my pedal powered parade machines), I have had plenty of opportunity to sort out myth from facts when it comes to braking. Here are some of the things I've learned:
Disc brake power is mostly a function of rotor size and pad material. There are cheap and horrible OEM calipers that waste the opportunity to deliver decent braking, but the cable-pulled Avid BB7 and its predecessor the Avid Mechanical disc are every bit as powerful as hydraulic brakes when set up with equal pads. Using their Speed Dial levers and carefully laying out and prepping cable housings gives you a lot of command over the feel and reactivity of the system, as does switching between different pad compounds. I like EBC Gold pads.
Cantilever and linear-pull brakes can be stronger than any discs. Really. They have 22" to 25" rotors with way more heat capacity and conductivity than disc rotors. There are more variables to be controlled and things to be adjusted in order to make rim brakes perform at their best, but it's no harder than keeping a bike index shifting crisply. Booster arches help, as do Kool Stop pads, high quality cables and careful setup. Linear-pull brakes are much easier to set up than cantilevers, so they are more likely to deliver powerful braking.
When hydraulic brakes have a problem, it usually causes a safety issue and often diminishes braking to zero on the affected wheel. Analogous problems with cable brakes usually cause progressive degradation of braking and are often fully addressable on the roadside or trailside. Hydraulic systems can't generally be serviced on the road and often not even in an ordinary bike shop! Many hydraulic systems require special fittings to do routine maintenance and special tools and proprietary parts to do major repairs. In my shop, fixing a rim brake or a mechanical disc is usually a while-you-wait repair, but fixing a hydraulic brake is always a scheduled repair that usually has to wait for special ordered items to arrive.
Disc rotors are less in harm's way than rims, but they are much more fragile. More often than not, they can't be repaired satisfactorily when damaged and thus must be replaced.
Users are generally more oblivious about how to set up and adjust cable-pulled disc calipers than they are about rim brakes. So even though mechanical discs are lower maintenance items in principle, they seem to be in disarray at least as much of the time as rim brakes. And hydraulics leave most users utterly helpless to do
anything to rectify their brakes when it's necessary.
Hydraulic disc brakes on bicycles are the brake equivalent of proprietary package wheels-- set up well from the factory, but much more difficult and time consuming to service, more dependent on proprietary parts and supplies, and much more expensive than the conventional equivalent. Disc brakes weigh a lot more than rim brakes, too, and cause weaker yet heavier wheels. They'll leave your bike out of service more of the time and cost you more all the way along. And when it comes down to it, they do not work any better than the real thing-- they just look and feel a little different. Maybe that's worth it to you, but not to me.
I use disc brakes on bikes with such fat tires that they don't play well with rim brakes. I would use hydraulics for a machine that had such a long, crooked route between the levers and the brakes that cables didn't work well. Otherwise, why bother?
Chalo
