[Alta825]

Figured this would be a good ? for y'all in the vintage forum-

Rumaging in an old box of my parts/pieces came across a pretty good condition XCPro microdrive crankset I ran for a year or so back in the day. What size BB would I need to run in a 68mm shell? I have a pretty good assortment of Shimano UN72's and was hoping one of the spindles would be a good length. Rather not strip the bike down to do a couple of trial/error, someone out there has got to have an answer....

 

[J Ro]

depends on the frame

Figured this would be a good ? for y'all in the vintage forum-

Rumaging in an old box of my parts/pieces came across a pretty good condition XCPro microdrive crankset I ran for a year or so back in the day. What size BB would I need to run in a 68mm shell? I have a pretty good assortment of Shimano UN72's and was hoping one of the spindles would be a good length. Rather not strip the bike down to do a couple of trial/error, someone out there has got to have an answer....

i'd say. I am currently running Pro's with a 125 length spindle on my Yo Eddy with plenty of clearance. Some frames may require less or more spindle length. Also you may prefer a different "Q factor" which may require some "trial/error"

 

[Fillet-brazed]

i'd say. I am currently running Pro's with a 125 length spindle on my Yo Eddy with plenty of clearance. Some frames may require less or more spindle length. Also you may prefer a different "Q factor" which may require some "trial/error"

Ya, its not a low profile crank so Id start with a 122 or so and go from there. Depends on your frame like J Ro said. The narrower the better for chainline and pedaling. Nice cranks.

 

[floibex]

xc pro md

... was the first "low q-factor" crankset. you should be fine with axles between 111mm and 116mm. with my bontrager race lites i always used 113mm ti axles. a '93 suntour cataloge you will find here.

ciao
flo

 

[Fillet-brazed]

... was the first "low q-factor" crankset. you should be fine with axles between 111mm and 116mm. with my bontrager race lites i always used 113mm ti axles. a '93 suntour cataloge you will find here.

ciao
flo

Ya, the ad calls it a low profile, but its not a low profile in the same way the 1992 M900 XTR arms were, where the arms arced out to the pedal. These are still old style needing the wider spindle.

The smaller rings however should allow a narrower spindle than say a non- micro drive XC Pro crank...

Do you use the 113 spindle with the XC Pro cranks?

 

[ssmike]

113mm also seems to strike a chord of rememberance with me. I'm running an XTR UN92 109mm bottom bracket with an XC Pro crankset for single speed use on my Salsa.

 

[DeeEight]

www.bikepro.com/guide.html

check the BB compatibily table.

 

[-Anomie-]

I also ran a 113mm with those cranks on my Bonty, which has a 68mm shell, but it really depends on the chainstays on your frame. That's where I would start though.

 

[floibex]

...

Do you use the 113 spindle with the XC Pro cranks?

standard xc pro (110 bolt circle) -> 125mm
xc pro md (94mm bolt circle) -> 110 and 113mm

ciao
flo

 

[Fillet-brazed]

I also ran a 113mm with those cranks on my Bonty, which has a 68mm shell, but it really depends on the chainstays on your frame. That's where I would start though.

Ya, I guess those smaller rings really allow it to come in according to that chart and what you guys are able to use. Ive got Microdrive on one of my bikes but just figured it was a 122ish just due to the old style arms. The XTR crank shows using a 109 with the full size rings due to its low profile arm shape.