I have a 2004 Cannondale ‘cross bike. Since the day I bought it, its front brake (it’s a cantilever brake system) has had the shudder of death. The sensation is rather like that of antilock brakes in a car, except that the front wheel is actually hopping off of the ground, which is obviously bad in an emergency stop situation on a bike. The problem goes away in the muck or when the rims have a lot of crud on them, but if you’re trying to descend at speed on a normal road, the front brake will throw you on the ground. I finally decided to do something about this.
I found this thread at bikeforums.net and discovered that I am by no means the only person to experience this problem, and that my bike is not the only bike to experience it. This came as a surprise to me, as my first two mountain bikes were equipped with cantilever brakes and I never experienced any shudder problems. Many people proposed many different solutions, but it was their explanation of probable causes that got me thinking and allowed me to get the thing fixed.
The cable hanger for the front cantilever was originally of the “headset spacer” type, in that it was a glorified headset spacer that happened to have the ability to terminate a brake cable housing. When braking, the fork flexes towards the rear of the bike. If you think about that motion, it actually has the effect of amplifying the tension on the front brake cable, thereby applying the brakes harder. This causes the wheel to lockup and hop, which I guess is better than having it just plain lockup and throw you on the ground.
At any rate, one person in the above thread suggested the following, and I thought it sounded like a good idea: replace that headset spacer cable hanger with one that bolts to the top of the fork, where a traditional road caliper brake or reflector might mount. The carbon fork on my bike is drilled to accept a hanger / reflector there, so I decided to track one down.
Harris Cyclery has one listed as a Tektro Front Brake Housing Stop f/Cantilevers. My Cannondale’s fork is too thick for the through-bolt that comes with the Tektro part, but I was able to find another bolt that fit suitably. This seems to have cured the problem for me. It also never hurts to have a tight headset and properly toed-in pads, but this change of hanger was the magic.