I find a 10 mm x 1 mm tap nice to have for the derailleur drop out. For just chasing threads, if you are courageous you can clean up with a 1/8" pipe tap (!) - just remember that it is tapered. If you go in too far, you have just made a unique 11 mm dropout. I haven't found matching derailleur mounting bolts for that size. Fortunately, I haven't needed one.
I also keep a pair of 9/16" pedal taps at home. Sometimes they are used for chasing threads -- just this week, in fact. More often, they are the instruments of blasphemy: I have converted a lot of 14 mm (French) crank arms to 9/16". The change is invisible, and it has been much easier not to worry about separate stocks of pedals for the bikes we ride.
Harvey Sachs
At 20:13 2/16/2001 -0800, alex wetmore wrote:
>On Fri, 16 Feb 2001, Tony Zanussi wrote:
> > I would love to hear from all what taps and dies (sources also!) that you
> > recommend for the minor work needed on small areas of bikes, or ANY that
> > you have found usefull. I am not talking BB's, but mainly axles,
> dropouts,
> > metric for 5 and 6mm, and ANY other, including pedals.
>
>As a home mechanic I haven't found myself using anything more than
>the 5mm and 6mm taps yet.
>
>5mm tap is really useful for cleaning up fender/rack eyelets on new
>bikes (sometimes they aren't tapped after painting). I also use them
>when drilling new eyelets into solid dropouts (did this on my folding
>bike, which has big BMX style dropouts).
>
>The only time I can remember using the 6mm tap was to fix some Deore
>XT II thumbshifters that I bought. They were $5 because the threads
>for the clamp were really screwed up (someone tried to shove way too
>big of a bolt into them). I drilled all the way through and retapped
>for M6. They've been doing well since.
>
>If I were repairing pedal threads I'd probably use the Edco helicoil
>style inserts. Loose Screws sells them, but they are too expensive
>to have "just in case".
>
>alex