Replacing Shimano Deore LX Chainrings -- Cannot find a compatible middle
 

Sorry, but here's another post from a guy who cannot find chainrings for his Shimano crankset.

My MTB has a Shimano Deore LX Hollowtech II Crankset with 44-32-22 chainrings. This crank can be seen here and here.

I can find the outer chain ring a few places. Example.

The inner chainring is also available.

However, the middle chain ring appears to be discontinued.

Nobody seems to stock it anymore. Typical example.


The Shimano derailleur compatibility chart sheds no light on this that I am able to discern. Am I reading it wrong?

Questions:

1) Any tips on how to identify a currently available compatible middle chainring?

2) If there are no identified compatibles, what are the critical specs to match up? Obviously the number of posts and the Bolt Circle Diameter. What else?

3) Is this a particularly difficult crank to match up with? Should I abandon ship and buy a new crank?

Don't know why any 32T 104mm BC 4 bolt ring wouldn't work.

You could probably use a 34T if you preferred that gearing.

There are plenty of ring options out there, from Shimano to aftermaret like Blackspire and Race Face.

Have you tried asking a bike shop rather than relying on online stores? They will be able to advise exactly what is needed, and may have it on the shelf.

You may find it is cheaper to buy a replacement crankset rather than the chainrings, would compare the price of a current Shimano SLX with the cost of individual rings as buying a complete unit may work out cheaper.

I'd use the M590 ring. There were some Shimano cranks with "gotcha" fit issues that I won't bore you with here, but the M580 isn't one of them. That's not to say that every 4-bolt 104mm ring will fit it, but the M590 should have no problem. It has flats facing the spindle (not semi-round like SLX and higher) and I think the stamped bumps next to the bolt holes are clear of the crank's spider tabs (if the bumps land on the tabs, the ring turns wavy when bolted down tight, something to mainly watch for when bolting Shimano rings to third-party arms).

Definitely look at the 9-speed SLX option too. Nice cranks, with a steel/fiberglass composite middle ring for extended wear life.

Hi, Sweetie.

You're kinda overthinking this here. In truth, any 104bcd 32t ring would work. Shimano uses some ramps and pins on their chainrings to optimize shifting, and i wouldn't blame you for wanting to keep the transitions between these ramps intact. As mechBgon mentioned, many other shimano chainrings will work. The Deore m590s he mentions would do nicely if you don't mind it being steel. You could also go with slx, or with xt if you wanted an "upgrade".

However, I personally think your best bet would be to get this:
www.jensonusa.com/Bicycle-Drivetrain/Shimano-LX-FC-M582-Crankset
Yeah, it's $90, but once you buy the three rings, you'll likely be at $70 anyway. This'd give you an entire crank for donor parts: new rings that you need now, new chainring bolts in case ya strip any of your current ones, new BB for when you need that, new crankarms should you ever thrash the current set... All for just $20 more.

hth
-rob