XT 9speed triple chain ring (outer) replacement or new crankset

User avatar
V17L
Posts: 349
Joined: Sat Jan 31, 2009 9:22 am
Location: Alice Springs, NT

XT 9speed triple chain ring (outer) replacement or new crankset

Postby V17L » Sun Oct 22, 2017 5:29 pm

Hi,
Thought I would ask the brains trust.
I have an xt 9 speed triple crankset, and the outer ring 48T is somewhat old, like its owner. I can purchase a new deore M590 crankset, but kind of wonder if it is just as easy to change the outer ring.

Looking on the interweb ie wiggle, I have found a replacement a TA chinook 104mmPCD four bolt. The marketing blurb espouses that the chain ring is not a stamped chainring, but rather made in a traditional manner ie on a lathe.

Has anyone had any experience with this brand of chain ring, re fit and longevity? Will I also need to purchase replacement bolts to hold it on. Which leads to the next question are all the bolts the same?

I have also wondered if the chain ring are agnostic in terms of 8, 9, or 10 speed, as the speed of the bike is more about the spacing between the chanrings. Is this correct?
cheers
steve t
Giant Defy 1

mikgit
Posts: 660
Joined: Fri Jul 27, 2012 8:26 pm
Location: Launceston

Re: XT 9speed triple chain ring (outer) replacement or new crankset

Postby mikgit » Sun Oct 22, 2017 8:54 pm

your crank comes with chainring bolts, you just reuse them for the next replacement chain ring (but i guess a new chainring could be a different width... but then where to get various size bolts?). Pretty easy, you undo, take off and replace and do up. So long as you know your BCD of the crank/ring and the teeth, just buy any one you choose. 8 & 9 speed work fine, 10speed may not.
Look 675 Pro Team, Cervelo R3, GT Xizang, GT Zaskar, Scott Spark 710, Yeti ARC

User avatar
bychosis
Posts: 5065
Joined: Sat Jan 14, 2012 1:10 pm
Location: Lake Macquarie

Re: XT 9speed triple chain ring (outer) replacement or new crankset

Postby bychosis » Sun Oct 22, 2017 9:16 pm

10speed should work the same as 8 and 9. The inner plate width is the same on all chains.
bychosis (bahy-koh-sis): A mental disorder of delusions indicating impaired contact with a reality of no bicycles.

User avatar
Duck!
Expert
Posts: 6353
Joined: Tue May 21, 2013 8:21 pm
Location: On The Tools

Re: XT 9speed triple chain ring (outer) replacement or new crankset

Postby Duck! » Mon Oct 23, 2017 7:59 pm

bychosis wrote:The inner plate width is the same on all chains.

No it's not; you take a link roller from an 8, 9, 10 and 11-sp. chain, and they're all progressively thinner. However due to the shaping of the chainring teeth there's enough tolerance for the differences to not matter.

What you do need to note with XT cranks is that although the BCD is common 104mm, the locating steps on the spider arms are closer to the holes than many other cranks - even other Shimano models - so if you wind up with different rings, expect to have to file the tabs back slightly to fit on the spider.
I had a thought, but it got run over as it crossed my mind.

User avatar
bychosis
Posts: 5065
Joined: Sat Jan 14, 2012 1:10 pm
Location: Lake Macquarie

Re: XT 9speed triple chain ring (outer) replacement or new crankset

Postby bychosis » Mon Oct 23, 2017 11:33 pm

Duck! wrote:
bychosis wrote:The inner plate width is the same on all chains.

No it's not; you take a link roller from an 8, 9, 10 and 11-sp. chain, and they're all progressively thinner. However due to the shaping of the chainring teeth there's enough tolerance for the differences to not matter.

Ok. I thought I’d read that it was the outer width that reduces while the inner width (gap between plates) was the same. ie 3/32” or 2.38mm for derailleur equiped bikes up to at least 10spd. I went searching (quickly) and what I read seems to agree. So the fog thick red is the same, but the space between is shrunk.

I know you’ve got a lot of knowledge on bikes Duck, can you point to what the inner widths are? The quick search on a phone I did didn’t provide any extra help.
bychosis (bahy-koh-sis): A mental disorder of delusions indicating impaired contact with a reality of no bicycles.

User avatar
Duck!
Expert
Posts: 6353
Joined: Tue May 21, 2013 8:21 pm
Location: On The Tools

Re: XT 9speed triple chain ring (outer) replacement or new crankset

Postby Duck! » Tue Oct 24, 2017 10:20 am

10-sp. is 11/128"; I don't know the exact figure for 11-sp. but it is slightly but visibly narrower.
I had a thought, but it got run over as it crossed my mind.

User avatar
bychosis
Posts: 5065
Joined: Sat Jan 14, 2012 1:10 pm
Location: Lake Macquarie

Re: XT 9speed triple chain ring (outer) replacement or new crankset

Postby bychosis » Tue Oct 24, 2017 11:17 am

I looked further on a proper computer, like with a bigger screen etc. Appears that there is conflicting info out there on the internet lands. Most general info sites (Wikipedia, Sheldon Brown, several others) seem to point to 3/32" for all, but apparently tech docs from KMC and Shimano point to 11/128" for 10spd and some 9spd.

There is agreement though that the outer chain width shrinks for every spd increase for anything over 7spd.

Still, for the .2mm difference in chain widths at 10speed chainring should run a 9spd chain no problems assuming it fits on the spider properly (see Duck's note above)
bychosis (bahy-koh-sis): A mental disorder of delusions indicating impaired contact with a reality of no bicycles.

User avatar
V17L
Posts: 349
Joined: Sat Jan 31, 2009 9:22 am
Location: Alice Springs, NT

Re: XT 9speed triple chain ring (outer) replacement or new crankset

Postby V17L » Tue Oct 24, 2017 1:48 pm

Thanks Duck, Mikgit and Bychosis,
Always good advice.

Will grab a file when I fit a TX Chinook to the outer ring.
cheers
stevet
Giant Defy 1

User avatar
Duck!
Expert
Posts: 6353
Joined: Tue May 21, 2013 8:21 pm
Location: On The Tools

Re: XT 9speed triple chain ring (outer) replacement or new crankset

Postby Duck! » Tue Oct 24, 2017 9:07 pm

bychosis wrote:There is agreement though that the outer chain width shrinks for every spd increase for anything over 7spd.

Actually, that's not entirely correct either, because the bike industry has a decidely loose interpretation of the word "standard" at times.... 7-sp. is an odd middle-ground, and chain width can be either 7.3mm, shared with 5 & 6-sp, or 7.1mm, shared with 8-sp.... The difference really only rears its head if you're chasing a joining link for "7-sp.", because a 7.1mm link won't fit a 7.3mm chain.

Still, for the .2mm difference in chain widths at 10speed chainring should run a 9spd chain no problems....

This is quite true; in fact (diverging slightly) many of the aftermarket MTB 1x chainrings are listed as 9/10/11-sp. In theory the only problems you could potentially strike are running a narrow chain (eg 11-sp.) on a "thick" 7/8-sp ring, but as I said previously, with the tooth shaping on multi-speed (2x/3x) chainrings, there is enough tolerance that it really does not matter.
I had a thought, but it got run over as it crossed my mind.

Who is online

Users browsing this forum: Google [Bot], xastorm