by: Naoki Sakai

Disc brake road bicycles are being popularized abroad and in Japan.  It is safe to say disc brakes are here to stay. The technology goes from a full hydraulic system to wire controlled flat mount brakes and thru-axles. Clearly, the braking futures in disc brakes, as its all weather, in wet conditions, are superior to caliper brakes.


As the market moves to less expensive prices for disc brakes, the challenge for quality control and efficiency becomes paramount in importance to riders, and segue ways naturally, to bicycle shops. The requirement for high precision vs. cost becomes a necessity.  When rotor-pad clearance is fractions of millimeters, having the caliper centered and square onto the rotor is critical. Getting the proper alignment is required for noise avoidance and excess pad wear.


Suffice it to say, the critical measurement makes for proper functioning disc brakes, where the mount of the brake to the frame creates a need for absorption of the transmission of force. Frames are reinforced around mounting areas with metal inserts and bolts to thread the brakes to, and these inserts have a need to be perfectly square. 


In disc brake systems, there are many areas of possible misalignment or unwanted movement, and interfaces and connection points need to be in perfect alignment for quiet, efficient and powerful stoppage.  The Mount alignment and preparation…called ‘facing’ is where braking performance is highly dependent upon. 


At Y’s Road Chigasaki, our main mechanic, Mr. Koyano, has recently made use of the Park Tool DT-5.2 flat mount kit, a very expensive, state of the art tool, used exclusively to create a flat mount for disc brakes.  The DT-5.2 is a highly detailed machine tool, as it cuts mounting areas to allow the caliper to sit flat and the rotor to run true.  It’s a minute difference, in some cases, fractions of a millimeter, but where pads sit so tightly to the rotor, a huge amount in functionality. 

If you want your flat mount brakes to run true, it is a must to use a high level tool as the DT-5.2. The caveat is if you want this service done here at Y’s Road Chigasaki, your bicycle must have been bought at Y’s road. Please see us if you have any questions and would like your disc brake mounts cut.