Originally Posted by
juvela
one hanger variable i have not seen much discussed on the forum is the distance from the centre of the axle slot in the dropout to the center of the hanger hole/tab.
on campag and on the copyolo dropouts this dimension is about 26mm. on most asian hanger plates and some asian dropouts this dimension is about 32mm. some home builders get a surprise when they attempt to get their maeda touring mechs rated at 34t to handle that size cog when fitted to a campag dimension dropout as happened to member LucasT-603 on his allegro build -
http://www.bikeforums.net/classic-vi...storation.html
Shimano has a tech sheet on this and describes for road dropouts 26mm is approved, and then also shows 32mm as being ok, and standard on mtbs.
what seems to be just as significant (for indexing) dimension is the face to face dimension between the inside of the axle land and the derailleur mount face, 7 mm as I recall is the suggested max.
There is also a radial dimension tolerance for the stop.