Derailleur hanger compatibility / fender angle I recently bought a pair of Qbicle Tangent fenders for my folding bike. The bolt for the derailleur hanger is in the way of the mount:



The fender is supposed to be installed at around this angle:


The derailleur hanger looks pretty much like this:


And the dropout is just flat (no grooves) with a hole beside it like this:


Is that derailleur hanger the only type of hanger that can be used for that kind of dropout?

I could install the fender so that the bolt of the hanger would pass through the fender mount. The fender would be mounted at around 170°; it would just cover the area between the 9 to 11 o'clock positions. Would the fenders be useless at that angle?
It looks like a tricky problem.  When I am faced with such problems I try to exhaust options before altering original parts..

With that in mind, I would look for a button head (rounded top) screw to replace the hex-head that hold on the derailleur hanger to see if the lower profile of the button head gives you the needed room to mount the fender in its designed configuration.  

If that does not do the trick I would weigh my options between the fender angles you mention (hard to comment on effectiveness not seeing pictures) and perhaps countersinking the derailleur hanger so a flat head screw can be used to buy you the clearance you need.

Final thoughts... the derailleur hanger hex head looks pretty beefy.  I have seen them attached with a couple 2M screws which are quite small.  Changing the screw to button or flat head will result in using a smaller hex wrench for tightening.  If getting the required torque to tighten it securely is a concern you may want to consider using some medium strength lock-tite as a measure against potential loosening due to vibration.