Riders and workshop mechanics keeping a 9-speed Deore or Deore-level triple running with a matching Shimano middle ring.
This is the 32T middle ring for the black version of Shimano's Deore FC-M590 triple crankset, the 44-32-22T set-up. Shimano's parts catalogue now lists the same part under the FC-MT300 (also 44-32-22T), so it suits either crank. It is a 9-speed ring on a 104 mm bolt circle with four mounting bolts, made from steel with a black finish.
Reach for it when the middle ring on your triple is worn, hooked or chipped and the shifting to and from it has turned clunky. It replaces the middle ring only, so your outer ring, inner ring, arms and bottom bracket stay where they are. Count the teeth and check the bolt circle before you buy, and remember it is a 9-speed ring, so it is not the one for a 10-speed crank. A worn chain can make a new ring skip, so give the chain a check while you are in there.
32T middle ring
Sits in the middle position of a 44-32-22T triple.
104 mm bolt circle
Four-bolt pattern on the 104 mm bolt circle Shimano uses for the outer and middle rings of the FC-M590.
Made for 9-speed
Shimano's pack marks it 3x, 9s and Deore, and it runs with HG 9-speed chains.
Black steel ring
A steel ring with a black finish to match the black version of the crankset.
Chainring
Fits
Great for
Maybe not for
One size: 32T on a 104 mm bolt circle with four bolts. It is the middle ring only. The outer ring, inner ring and crank arms are separate parts.
Same part, two names
Shimano's exploded view for the FC-M590 lists this ring as the 32T black ring for the FC-M590-L, and Shimano's current catalogue lists it as the 32T ring for the FC-MT300. It is one part, so a ring sold under either name is the same ring. Silver rings for the silver FC-M590-S have a different part number.
