Finding compatible chainrings for Shimano Deore LX Crank

canoeboater

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:
http://velospec.com/components/shimano/fcm580
And here:
http://techdocs.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/FC/EV-FC-M580-2356C_v1_m56577569830608889.pdf

I can find the outer chain ring a few places. Example:
http://bikeparts.com/search_results.asp?ID=BPC313768

The inner chainring is also available:
http://www.niagaracycle.com/product_info.php?products_id=404590

However, the middle chain ring appears to be discontinued. See here:
http://www.treefortbikes.com/product/333222347915/324/Shimano-Deore-LX-FC-M580.html

Nobody seems to stock it anymore. Typical:
http://www.bikesonline.com/deore-lx-fc-m580-32-tooth-9-speed-chainring.htm

The Shimano derailleur compatibility chart sheds no light on this that I am able to discern.
http://www.shimano.com/publish/content/global_cycle/en/us/index/tech_support/tech_tips.download.-Par50lparsys-0025-downloadFile.html/01)%20Drivetrain%20Compatability%20Chart.pdf
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?

nicklouse

Any with the correct BCD will work.

104mm a file may be needed on the shoulders as not all makers use the same size and the same makers change what they use as well.

cobba

Same Part # Y-1FU98020 http://www.woollyhatshop.com/index.php?_a=viewProd&productId=383&catId=0

Chunkers1980

I've actually got two of those cranks, must be different years as the rings that came with them and the axel are different. They even have different pre-tension bolt threads. Weird, so in short it's like Nick says, but a deore ring should just bolt right on.