Finding out what bottom bracket length is needed

First fixed build so I have a few teething errors

I've measured both my chainlines, front =54 and the rear =40ish, but I can go up or down on this by 2mm.

http://www.chainreac...x?ModelID=17473 That BB has been suggested, but I'm not sure what size to go for.

Make of crank is unknown :(

Will the 68-110 be fine?

Cheers

[URL="http://www.sheldonbrown.com/fixed.html"][/URL]

Depends on the cranks you want to use really...If you're going to be using road cranks, then a spindle of 107mm or less should suffice.

This thread should help:
https://www.lfgss.com/thread3372-7.html#post1661401

Thanks Pifko, useful thread, but unfortunately I don't know the make of my chainset/cranks.

If I measure the spindle length on my bike (which gives me the crap chainline), minus 68 and divide by two, then minus 14 (54-40) then double it and add on 68, then this should give me the figure I need? Or is that fail maths

http://www.sheldonbrown.com/bbsize.html#chainline

Cheers Andy, that helps to a degree, but still seems to suggest that I need to know my crank make.

If it is any help the BB spindel I am running is a 68/120......just want to know if going to 110 or 107 will bring the chain ring in enough

What type of cranks are you using?

I bought them second hand so don't know. I'll get a photo and see if anybody can ID them, could help I guess

Are they road or track?

Track....or at least designed in that fashion:

Ignore the fact the lock ring is possible cross threaded :P

Have you had to cold sept the rear to get a 120mm hub in? I'd go for a 107mm BB.

Rear was already at 120 which I was surprised at (bike is a Triumph Cyclone - made by Raleigh)

I guess 107mm is my best option before I have to redish the wheel, cheers for the help (prompt help I will add!)

Have fun.