Conversation of a rear rack to fit on disk brakes
The last brake upgrade to disk brakes was a problem. The brake caliper didn't fit under the rack mount. I had the choice disc brake or rear rack. Stupidly there was also a Rohloff speed bone. The part needed additional space, I didn't had.
So, I filed an adapter of alu. So the caliper and the speed bone found place under the adapter. The rack was rised for 100mm, what is no problem in my case. The frame has 64cm (25"), so the saddle is still much higher than the rack.
Above: initial state
Above: final state
Above: sectional view A-A
Above: sectional view B-B
To prevent bending stress of the M5 thread, the alu adapter is made in one piece and so it takes the whole bending load. The thread only takes tension.
On the right side, the punched flat section (original state) was doubled with the leftover flat section form the other side and so it rised the rack too.
So, all was done, my construction proved itself on daily commuting, 34 kms a day and a tour from my home to Vienna and back. Meanwhile it has stand 3000kms with two panniers.
The alu, I used is a hard one, but no duralumin. Nevertheless, I had no fatigue fasilures.
If there is no speed bone, the complete structure can be a little bit flattened (less offset) to lower stress.