Bicycle Hack: Can You Use MTB Mechanical Disc Brakes With Road Brifters?
Learn by error, then adapt for free
I converted my 26" mountain bike into an "all road" bike. This included the addition of drop bars and 27.5" (650b) wheels and tires. For brakes I went with mechanical discs. I decided to buy a cheapo Chinese disc brake set off of eBay. For $30 I got front and rear discs, calipers, and cables!
I installed the disc brakes and later on I realized that mountain disc brakes will not work well with short-pull road brifters. MTB disc calipers have a long pull ratio, much like v-brakes. Road brifters are designed to work with short-pull road caliper rim brakes.
They worked but felt mushy and allowed a lot of lever travel before the brakes would bite.
I discovered a very simple hack that will allow you to use long pull mountain bike disc brakes with short pull road brifters. This hack also improves modulation, as well as giving a crisper feel. There is slightly less power but it is not a huge deal. There is plenty of stopping power to go around if you use discs.
This article is not for every type of cyclist. It is aimed at the do-it-yourself type of cyclist who will not, or cannot, spend thousands on a bicycle.
It is for the mechanically inclined cyclist who is not afraid of building or repairing his/her own machine: the kind of cyclist who has a stash of bike parts, odds and ends, that are still 'good' but completely out of date. You can't throw it away because you might need it someday. If this describes you, then read on.
Long Pull / Short Pull
Road bikes traditionally had rim brake calipers which required a very short pull to actuate. Meanwhile, in the mountain bike world, popular V-brakes required a much longer pull, so when disc brakes were released, the long-pull characteristics of the V-brake levers were retained.
What I Did To Make It Work
By simply altering the mounting point of the cable you can have the functionality of the mountain disc brakes with the usage of the regular short-pull road brifters and without having to purchase new short-pull mechanical road disc calipers or an entire hydraulic levers-and-calipers set up.
The idea is to simply re-position the brake cable on the other side of the pull arm. Refer to the photo above. It appears that the cable goes down then around to the mounting screw. I would also recommend replacing the screw that holds the cable to the caliper for a longer one. This will give the cable somewhere to hold onto so it will not slide off the side of the caliper's bake arm. With this new position you're altering the geometry of your pull, your cable is pulling much less, while the caliper's brake arm is moving the same distance; yes you're getting a little bit less power, but I find the loss of power isn't the worst thing in the world. The modulation is greatly improved and the overall feel of braking and gives you much more confidence over having to pull almost to the bar before the brakes would bite. One thing to watch out for is your adjustment barrels. With this hack, your cable is traveling at a harsher angle and it might it might eat away at the cable. To avoid this, I would screw my adjustment barrel so the end of it stays just inside the body of the brake assembly. Give yourself at least five or six turns to maintain some adjust-ability.
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