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I bought my frame from a sponsor of this site. I asked them to install the BB which I had bought for my FSA double compact crank, a 108mm. The bike came just fine, I built it and rode a few times. I kept throwing the chain over the small ring on front downshifts and got sick of it. I took it to the LBS and had them diagnose.

They tell me the wrong BB length was installed and the one in there was for a triple!! They installed a like model 108; the bike indeed shifts more reliably.

OK, I could use a new drivetrain on my commuter and have need for a triple BB. Except, I'm not positive of what I have.

It's an FSA Platinum Pro Titanium. The only markings which COULD be size are:
801.37" x 24T (I'm assuming the 24T is a thread pitch and that 801.37 doesn't convert to anything metric) and NN122 (Their's no such thing as a 122mm spindle)

It measures (as best I can) 4 5/8" which converts to 117mm. Besides, exactly which two points are measured from?

So, what in the wide, wide world of sports do I have? I think it's 68x118, but I'm not positive. I have an email open to FSA tech support, but no answer yet.

Thanks.

Dave
 

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measure from outside of the axel ends. the one you have sounds like the 118. one way is to compare lenghts to the shimano counterparts. a triple ultegra is 113- 115, triple campy is 111mm for example. i had a bb uncrew on me because the shop installed the wrong lenght. sell the triple on eBay. visit http://www.fullspeedahead.com/fly.aspx?layout=product&taxid=29&pid=72 to see the info on your bb. Measure from BB shell to either the center of a double crankset or the middle chainring (on a triple crank) to establish chainline dimension. then go to shimano for whatever your running and see they would recommend. Chainline dimension determines spindle length. refer to http://bike.shimano.com/media/cycli...ponents/FC/SI-1F30H_v1_m56577569830572764.pdf for shimano......
 

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ISIS BB spindle length, threading

From the discription, it sounds like it must be an ISIS splined spindle. The ISIS standard calls for only 3 different spindle lengths - 108mm, 113mm, 118mm. 4 5/8" works out to 117.475mm, so your BB must be a 118mm.

The marking 801.37" x 24 TPI must refer to the threading of the cups/rings. A standard English BB shell uses a 1.37" x 24 TPI thread. English threaded BB shells come in only two widths - 68mm and 73mm. 73mm is found almost exclusively on mountain bikes, so your road BB shell must 68mm wide. My best guess is that that 8 refers to 68mm, and the 01.37" x 24 TPI refers to the threading.
 
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