Using my best schoolboy art, here is the problem, using a 42t ring

with a 102BB the chainring bashes (touching, jamed against, won't move) on the chainstay and is already at about 44mm chainline,

with a 107BB the chainring clears the chainstay but I am out at like 46-47mm now,

so, is there a way to get a 42mm chainline? Bend the chainstay out of the way? Bash a dent in with a hammer? Something less drastic? ??!?!!!?!

nurse? NURSE!!!

does the chainstay already have a dent for clearance? if so you can make it bigger (did that on my MTB conversion) if not you can make a dent for more clearance, or go for a wider rear hub, the londonfixiebike shimano bolt on jobbies give a dishless wheel with 46mm chainline using a 10mm spacer each side.

If there is enough space on the rear threads, use an old BB lockring to space it out a bit.

yep I go with this advice make the crimp bigger or new hub. To make the crimp bigger you can either make a crimper or use a (ideally shaped) block of wood behind the chainstay for non denting support and a cold chisel.

I will have a go at making a crimp I think, would like to keep it to standard track wheels if possible
Cheers

...I'm not going to change your sheets again, Mr Hastings.

just a thought, if your getting a 44m chain line with a 102bb are you planning on changing cranks to get down to 42mm?

I seem to remember when crimping the stay on mine, I put the stay in a vice with a bit of very soft wood behind it to prevent crushing as best I could, then I think I used a little nail puller crow bar, put the flat tip where I wanted the crimp section extending (mine was already crimp/dented I was just lengthening it) and wound the vice up gradually tighter and I think I had to wiggle the frame a bit as I went until the crimp/dent was long enough.

Put the crimp in with a pair of pliers, and a long flat piece of metal along the back to stop me crimping both sides. Used a small bit of wood between the pliers and the frame to prevent scratching, seemed to work fine, I have added a crimp of about 3mm and all is well.

My mesurements where based on the cranks not going full on because they where stuck against the chainstay, with the crimp, I am pretty much bang on I think.

Cheers for all the advice