http://www.parktool.com/repair/readhowto.asp?id=94
Once you've removed the cranks and the BB the length will be on the BB. Failing that, just take it to a shop and have them supply suitable replacement.
@hippy started
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http://www.parktool.com/repair/readhowto.asp?id=94
Once you've removed the cranks and the BB the length will be on the BB.
Failing that, just take it to a shop and have them supply suitable replacement.