Chainline weirdness with fc-m460 square taper chainset

davee128

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?!

The Rookie

Easy, the cranks want a longer BB, someone has swapped to the wrong one at some point, most Shimano want a 122 which would move your rings out 2mm.

Not ancient, my MTB (Niota, link in sig) is a 2006 frame and cranks, it will get offended.

davee128

Yeah, that's the only thing I can think of too, but the only info I can find online suggests 117.5 is correct:
http://www.moruyabicycles.com.au/conten ... nkset.html
http://forums.mtbr.com/shimano/fc-m460- ... 61524.html (unfortunately linked shimano document no longer available)
In addition it is quite hard to find longer BBs.
I think I'm just going to swap it out for hollowtech II.

I think 1995ish counts as ancient for a front mech doesn't it?

The bike is also on 1998 Deore LX shifters! :-o

The Rookie

Plenty of 122 square taper around, you just need to look!

I get 88 hits on eBay for starters.