Forum home Mountain biking forum MTB workshop & tech

Chainline weirdness with fc-m460 square taper chainset

davee128davee128 Posts: 26
edited April 2017 in MTB workshop & tech
So I have a 2005 vintage Specialized with 68mm BB shell that I bought 2nd hand. It came with BB and cranks (Deore m460). I believe the cranks were original to the bike when new. No idea about the BB but the axle length was 117.5mm. I replaced the BB when it died, with a 118mm as that was all that was available. The front mech I've been using was a circa 1995 Alivio. It's never been 100% reliable shifting to the granmy, but has been ok most of the time with the limit screw out at max (only just making contact).

I tried to upgrade the ancient front mech to a 9 speed deore triple in the hope of getting better shifting and found that it wont go anywhere near the granny!

Investigating this I found that the chainline is way off. Having trouble measuring it accurately, but I find that the chainline is below 45mm.

The cranks have never come loose so I'd be surprised if the taper was knackered.

Any ideas why?!


Sign In or Register to comment.