I have.
Made several changes over the standard fittings, though. For one, I filed/ground/cut both halves of the QR that clamps to the seat rails flat, getting rid of the original curved profile. That’s allowed me to put the QR clamp further back on the saddle rails. Yes, that’s taking a risk because it reduces the clamping area, and therefore increases the pressure n the rails. But they’re pretty solid.
And I also modified the stays that go to the rack mounting points, by threading the end of the stay and using a couple of M8 nuts on it. In part, that’s because I managed to strip the thread in the original Al fitting. But mostly it provides a stop that absolutely prevents the stay from sliding through the fitting - adding to the strength pretty significantly.
Note that this was all done because (1) the B17 has stupidly short rails, and (2) I had a couple of incidents where the saddle tilted backwards, pressing onto the mudguard which in turn pressed onto the tyre (and I thought I was just having a bad day, getting consistently dropped by the group; Nope, I was trying to ride with the brakes on!). The extra nuts on the stay make the bag support making contact with the mudguard pretty much impossible. Plus that second stay gets close to fouling the rim brake unless it gets significantly modified.
I don’t feel the need to use the second stay; this bike isn’t intended to be any sort of "load lugger" (if it was, I’d use a proper pannier rack).
At some point I’ll get around to tidying it all up, painting bits black, chopping off extraneous bits etc.
- QR clamp
- Modified stay
<edit> Less a garage, more a sort of bike workshop meets general dumping ground. One of my winter projects has to be getting rid of the junk and rubbish, reorganising the limited storage, and returning the space to car parking and woodworking area.