My LBS is building up a bike for me and has just told me
the Raceface single ring I was gonna put up front won't fit the Shimano crank
as new Shimano cranks aren't 104 diameter anymore.
So they're saying I either just use a standard middle ring or buy a new crank.
Saying even a Saint ring won't fit the crank, which is a basic Deore jobby.
I've trawled web and can't find any reference to similar problems, anyone else had this??
No idea about the not being a 104 BCD thing but most non-orignal (even other model shimano) chainrings tabs need a little tickle with a file to fit shimano spiders , unless there the original model too. Your LBS probably aren't interested in filing down a brand new chainring though (unless the BCD thing is correct)... I've been filing down chainrings tabs to fit, without issues for years and will continue to do so (some ppl prefer to file the spider).
Think some 2x10 cranks have odd BCDs, and some SRAM 1x ones, but most Shimano cranks should work just fine.
"What crank is it?" is probably the question to ask here.
Cheers, he actually showed me the bits and said they used to just file them down but now the actual bolt holes don't line up and are different diameter. So Shimano not 104BCD.
I put a Middleburn ring on an XT crank a few years ago but they've changed apparently - just seems odd I can't find evidence of others having the same problem, must be plenty of folk who've put a single ring on a Shimano crank.
honourablegeorge - it's a Shimano FC-M622. Doesn't give the BCD on Shimano's site.
Shimano slx crank here with a single blackspire ring, no issues.
FC-M622, do indeed have a [url= http://www.bike-discount.de/en/buy/crankset-fc-m622-40-30-22-175mm-schwarz-80081 ]96/64 BCD[/url] apparently, seems counter-intuitive after producing 104/64 for so many years.
([url= http://si.shimano.com/php/download.php?file=pdf/ev/EV-FC-M622-3547.pdf ]Shimano document says the same[/url])
kayak23 - is that a newish crank?
Yeah, the newest slx.
Thanks z1ppy. That's pretty conclusive then. Seems SLX and XT are 104 so looks like I need an(other) upgrade!
cheers.
Hmm. It's for 650 and 29er wheels, you see. Clearly needed a new BCD
"Shimano Crankset FC-M622 40/30/22 175mm schwarz – Crank. New Dyna-Sys compact 3-speed crank with 40-30-22 teeth for 27.5 - or 29-inch wheels."
It's a cheapo crank too, why make that a weird size?
Mainly to bugger up my day and mean I don't get to ride my new bike home I guess.
It's 29er specific (seriously, according to Shimano).
Surely so the 30t chainring can fit as normal, rather than have the little tabs to space it out as per the raceface 30t 104bcd chainring?
Makes sense to me... Though it is annoying.
Odd that it's the BCD that's the issue, it's normally the middle ring tabs that cause the problems. Shimano changed their cranks from 90mm to 88mm ID a while back, So aftermarket rings will be baggy on Shimano cranks but should fit.
Found a thread that explains a bit....
[url= http://forums.mtbr.com/shimano/bash-rings-new-96mm-bcd-pattern-m782-cranks-876969.html ]http://forums.mtbr.com/shimano/bash-rings-new-96mm-bcd-pattern-m782-cranks-876969.html[/url]
and ends with a possible solution - Blackspire doing 96mm single rings
[url= http://www.blackspire.com/SNAGGLETOOTH-96BCD-Chainrings ]http://www.blackspire.com/SNAGGLETOOTH-96BCD-Chainrings[/url]
Now need to find a decent price with shipping.
Fell foul of that one recently. Asked Works Components who said they'd have new 96bcd ones before end of year
honourablegeorge - Member
Think some 2x10 cranks have odd BCDs, and some SRAM 1x ones
SRAM have certain 2x10 cranks that are 120/80 bcd. Really annoying when I discovered that.
However a lot of their cranks also have replaceable spiders and you can get ones with 104bcd, and their 1x spider is available 104bcd. Plus you can get spiderless/direct-mount chainrings that don't need the spider at all.
As for the middle ring file off thing, I found that was the case with a triple if trying to fit a single ring to the middle. The single rings were designed for single spiders and needed tabs or crank filing down slightly.
I'm buying a chainset to run a single ring on. What's best to get, Deore or SLX? Double or triple?
Deore or SLX will work fine. Triples give better chainline in the middle ring position without having to faff with spacers.
Just make sure you get one with a 32T middle ring to avoid the odd BCD issue of the OP.
Found this now too, doesn't mention BCD but they are all 96.
[url= http://www.chainreactionhub.com/latest-news/1283-first-look-shimano-chainsets-for-big-wheel-mountain-bikes ]http://www.chainreactionhub.com/latest-news/1283-first-look-shimano-chainsets-for-big-wheel-mountain-bikes[/url]
spyke85 - Member
I'm buying a chainset to run a single ring on. What's best to get, Deore or SLX? Double or triple?
Just bought this - http://www.merlincycles.com/shimano-slx-m670-10-speed-triple-chainset-58295.html to do exactly that after my old XT crank finally required replacing.
Went for triple as the chain line is a little better and for the money you can't go wrong imo
RF only seem to do a 104, 110 and a 130 bcd chainring.
It's so people can now run a 28t narrow wide - once chainring makers do like they did for making 30t fit on 104 bcd cranks. cool. great thinking