Deore Cranks / XT Chainring Compatibility?

BoredHousewife

This may seem like a stupid question but should these be compatible? I went into Evans today and asked for a 36 tooth middle ring which was compatible with my Deore cranks but when i've came home to fit it the ring just doesn't quite sit right, its as if the bit that meets the arm is about half an mm too long. Should it be this way or is it the wrong ring? The ring i got is genuine Shimano marked XT on the packaging.

Thanks

supersonic

I do know that Deore middle chainrings (for none HT2) cranks need a bit of filing to work on the newer XT and LX HT2 chainsets. Its possible that vice versa (as here) the fit isnt quite right. What model number chainring is it?

BoredHousewife

sonic to the rescue again......cheers

chainring is FC-M761, cranks is FC-M510. Looks like i'll be buying a cheap file tomorrow then...

Shame 'bout the GT register, that could have been coooool 8)

supersonic

Ah, the FC761 is indeed the crank with Hollowtech2.

Sure the GT fans will appear lol!

nicklouse

Mmm just had a look at some HT rings i have here. Mmm they are the same as the old outer one. just checked against a bash ring.

ROCHA

I've had a similar problem with an old shimano alivio square tapper crankset. I wanted to have one single ring, the big one. For the chainline to be ok I had to fit the big ring in the position of the middle ring. The problem was that the 42T chainring had a slightly smaller inner diameter than the 32T, so it would't fit. I filed the crankspider instead, because most non shimano rings have similar measurements to the 42T. It was a cheap chainset and the chainring was tough steel, so it was a lot easier to file the aluminium spider.

From what you're saying Hollowtech II cranksets have an identical interface for the outer and middle rings. I wished my old crankset was like that! Why was it different?

BoredHousewife

ROCHA wrote:

I've had a similar problem with an old shimano alivio square tapper crankset. I wanted to have one single ring, the big one. For the chainline to be ok I had to fit the big ring in the position of the middle ring. The problem was that the 42T chainring had a slightly smaller inner diameter than the 32T, so it would't fit. I filed the crankspider instead, because most non shimano rings have similar measurements to the 42T. It was a cheap chainset and the chainring was tough steel, so it was a lot easier to file the aluminium spider.

From what you're saying Hollowtech II cranksets have an identical interface for the outer and middle rings. I wished my old crankset was like that! Why was it different?

I chose this option, felt like a crime but it worked. And next time i buy a ring i'll be getting new cranks anyway so poop to it :P