front brake ?

[Slip Kid]

what size allen wrench is supposed to
be used to take off the caliper hold downs?
1/4" and 6mm are too small and
slip. 3/16" and 7mm are too big. !!! ???

:dunno:

 

[Matthew Currie]

I'm almost certain it's 7 mm, but if the heads are a little rusty, it may be a very tight fit. It is definitely metric, though. Try tapping in a 7 with a small hammer.