Originally Posted by
_ForceD_
by not using that mounting bolt I think you may in danger of the claw slipping/pivoting back-and-forth on the axle without the second securing point. Seems like to prevent that you'd have to overtighten the QR to what might be too tight.
I disagree. The QR needs to be tight enough to keep chain tension from pulling the wheel forward, and there should be very little rotational force on the derailleur claw. This set-up will undoubtedly be a nuisance when removing or installing the wheel, but otherwise should work fine.
@
hokiefyd Derailleur 'claw' adapters are available at bike shops for less than $10. Having one welded on - probably aligned so the back of the claw's slot is lined up with the back of the dropout would be fine. Keep in mind that welding can weaken the material being welded, and dropouts are a fairly common point of failure on bike frames, but in my opinion (FWIW) is that it would likely be fine.
I would actually get two claws, or some other item to weld to the non drive side to make that dropout thicker as well. Stamped dropouts like that are often so thin that you need to shorten the lengths of the axle stubs so the QR can tighten properly. If this is not an issue with your bike than ignore this advice.