Topic starter
Hi folks
My old Genesis commuter bike has a Deore FC-M442 triple chain ring. I think this is long discontinued.
As part of a recent drive train service, I replaced the chain and cassette, but also noticed the middle chain ring was worn.
I’ve bought a Shimano FMC-590 middle chainring to replace it (double checked, and it’s 9 speed/triple, and measures identically to the one I took off). I made sure the notch alighted with the crank, so think I fitted it correctly.
In the stand, the chain ran through all the gear combinations fine. When tried it on the road, it was fine on the level, but on climbing  (I was on the middle chainring), and putting a bit more strain on the chain, the chain was jumping and skipping, and it didn’t feel right.Â
I’ve put the old chainring back on, and it’s all fine again.
I’m wondering if there is an incompatibility between my FC-M442 large chain ring and the new FMC-590 middle chainring. Does anyone know if this is the case?
Would replacing the large chainring with an FMC-590 solve my problem? It’s over £30, so I don’t want to buy it unless I’m confident it will solve my problem
I can’t find a replacement FC-M442 middle chain ring; there are some second hand chain sets on eBay, but I’d rather fit a new item.
Appreciate any help
Thanks
Posted : 23/03/2025 8:47 pm
Is the chain catching anything on the crank when under load with the new chainring?Â
Sometimes chains settle down and bed in. But you don't want slipping under load.Â
Over the years I've mix n matched a few chainsets and occasionally they have needed spacer washers or different length bolts to fit different cranks. But if you have as you said replaced cassette, chain and chainring I would of thought it should work. There must be something out of place that is lifting the chain under pressure?Â
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Posted : 24/03/2025 8:36 am
If everything is correctly fitted and it’s only jumping when under load on the middle ring then what you have fitted either side is immaterial. I know that you say you’ve replaced the chain but the symptoms you describe point to a worn chain… I’ve got lots of brand new XT, 9 speed stuff in the workshop as I plan on living to 120… I’ll have a look later and direct message you.Â
Posted : 24/03/2025 12:52 pm
A middle M590 will fit the same as your M442, so buying that won't fix anything. It's not incompatablity between the old 44t and new middle ring, that doesn't really happen and if it did would only affect shifting between front rings.
You cut the chain to the correct length? Have you played around with fine-tuning the rear derailleur?
Posted : 24/03/2025 9:09 pm
