Well, I’ve been on a journey dealing with brake chatter from this 203 mm disk. Before I get into it, I’d like to thank kunstrasen again for sharing the design to stiffen the D’brake adapter’s large cantilever arm.
I copied Kunstrasen’s basic design, but since my son has a 3D printer, I thought I’d design a nice (plastic) bracket to clamp onto the KH frame. Also, I noticed that one of the M6 threaded mounting holes on TRP’s “disk brake adapter” (a.k.a., the standard mountain bike bracket that fastens to Unicycle.com’s D’ Brake Adapter to position the brake caliper at the correct location for the 203mm disk, phew…) was nicely pointed in the direction of the KH frame.
So, I though I could easily lengthen the M6 screw and then hold the extended screw with the 3D printed bracket mounted to the KH frame. The design worked sort of nice. Check out the pic below:
The problem was that I did not buy a longer M6 screw. I tried to wedge a rod between the 3D printed bracket and the “disk brake adapter”. (Figuring that the rod would always be in compression.) After a few rides, the relatively flimsy 3D printed bracket became lose and the rod fell off.
So, for the 2nd design attempt, I still used a relatively weak 3D printed bracket, but this time I got rid of the original M6 socket head cap screw and bought a 4" long M6 threaded rod. I then used the threaded rod to mount the Slate T4 caliper while the 3D printed bracket held the other end of the threaded rod (still just used compression between the 3D printed bracket and the threaded rod). Two pics below:
This worked great for several weeks. But, I’ve been braking pretty hard and either from yielding the plastic bracket, or creep, or low cycle fatigue, the 3D printed bracket started to twist on the frame and under really extreme conditions I could hear the brakes start to make noise (I believe this is the precursor to chatter once the bracket became even looser).
So, I bit the bullet and redesigned the bracket out of aluminum. I know that the bracket is huge, but this 3rd try has got to work! Also, I’ve threaded the M6 rod into the aluminum bracket. Super stiff… Below is my final design. if this does not work, I’m biting the bullet and buying a 180 mm disk and the Shimano Saint caliper…
Look at how little clearance there is between the disk and the bracket. Hope this is OK. It was Ok for ~6 weeks of riding with the plastic bracket (and that bracket had even less clearance because of thicker walls).
In a few weeks, I’ll let you know how this works. My guess is that it’s going to be super solid and I’ll be able to brake hard and fast with no chatter!