calculating bb axle length for any bike

[Markybeau]

Is there a method for calculating what length axle will be needed for a bottom bracket and crankset combination? If so, can an enlightened person share that information please because I'm in the dark.

I'm swapping an octalink es71 bb 113mm and Xt m751 crankset for a square taper STX-RC mc40 on a 94ish C16R.

 

[konacarl]

The best place is sheldon browns website. Theres a full listing of BB axle sizes required for cranks. You will need to check the BB width though.

 

[Markybeau]

Re:

I was going to suggest taking a look at Sheldon...should take my own advice.

Ta

 

[whayne]

Re:

Will be a 113mm for a STX crank.

Regards

 

[Splatter Paint]

Re:

FC-M751 requires a 113mm axle for a 47.5mm chainline, 118mm for 50mm chainline

FC-MC10 > FC-MC40 requires a 110.5 mm axle for a 47.5mm chainline, 113mm for 50mm chainline

SP

 

[FluffyChicken]

Honestly, not rule .... unless you know the profile of the crank. I guess you could work it out from pedal distances, chainring positions etc.

But for Shimano, just go to their tech site and look the crank up and read what it says. (or ask, or use sheldon or use google.)

FC-MC40 https://si.shimano.com/#/en/search/Keyw ... &name_web= Steel Orange with 7/8 speed will use 47.5mm chainline normally and you'll get as mentioned in the previous post. (or like me you grab the 1998 components catalogue and just read the numbers)

 

[foxb13]

Also Bikepro: http://www.bikepro.com/products/bottom_ ... table.html

 

[Retrobike93]

Good info