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How to measure BB size?(5 posts)

How to measure BB size?overtrained
Aug 7, 2003 1:21 PM
Going to change my BB from square taper to octalink. How do I know what BB size I have?
re: How to measure BB size?Akirasho
Aug 7, 2003 1:36 PM
... aside from width and thread issues... and assuming you're talking road (probably 68mm), Octalink BB spindle lengths are directly related to the crank/rings used (double or triple).

http://www.sheldonbrown.com/gloss_bo-z.html#bottom

If you're using a double, it's 109.5 mm... a triple uses 118.5 mm

Be the bike.
Thanksovertrained
Aug 7, 2003 1:41 PM
Actually it's for my Mtn. Bike. BB shell width x spindle lenght.
DRATZ!!!!Akirasho
Aug 7, 2003 1:58 PM
That's different then! I assumed the wrong thing (road)...

For MTB, you've got 113 mm and 118 mm .

http://www.shimano-europe.com/cycling/catalogue/content_prodx.phtml?pid=10006&psid=1
http://www.shimano-europe.com/cycling/catalogue/content_prodx.phtml?pid=10006&psid=1
http://www.shimano-europe.com/cycling/catalogue/content_prodx.phtml?pid=11140&psid=1

http://www.shimano-europe.com/cycling/index.phtml

Measure your current BB spindle length to find an approximation (note: it's still somewhat dependent on crank/rings and chainline on your specific frame).

Be the bike.
mtbRusty Coggs
Aug 7, 2003 2:23 PM
shell width is 68 or 73mm, measured on the frame,and Spindle length still has to match crank for application, length and type. www.branfordbike may have some of the specs and guidelies in the catalogue section.