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Discussion Starter · #1 ·
Calling all Shimano compatibility experts... so I have a 4 bolt LX Mega9 crank.... I picked up some chainrings at the LBS today and the middle ring appears to be incompatible.... all bolt holes are at the same spacing... but the new chainring appears to have an approximately 1.5 to 2mm "nub" to the inside of each bolt hole.... just enough to make it not fit on the spider... from what I know both chainrings are LX (as is the crank, 2003 vintage).... do i need to lay off the crack pipe or does shimano have some other wacky sizing issues besides hole spacing?? I wish I had part numbers on the pieces, but I onlhy have a part number for the new chainring (FC-M580).. here is what i got... old chainring says M9 N-32 and across the hole from this it says AE... new chainring M9-S32 and across the hole it says CL on this one it also says SG-X below Shimano...
Any info would be cool... I'm gonna call the LBS on Monday and try to figure this out, but I'm kind of a need to know kind of guy, so I thought I'd ask on here....
FWIW I almost took a Dremel with a grinding wheel on it to the little nubs, but then my better judgement kicked in...
Thanks for the help...
 

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having same issue...

BUMP! Anyone? I am having the same issue trying to use a shimano middle chainring (from a hone Crankset) on a set of race face crank arms... Shimano seems to spec a chainring with the same BCD as common cranks (104 4 bolt) but that does not fit the splines of common cranks. I thought I was going crazy for a sec too, and have a sweet little build on hold till I have the time to take out the dremel as well. :madman:

It is frustrating when dealing with proprietary stuff, and I think shimano's newer chainrings may be proprietary. Why companies do this I will never understand.
 

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dumpy said:
Calling all Shimano compatibility experts... so I have a 4 bolt LX Mega9 crank.... I picked up some chainrings at the LBS today and the middle ring appears to be incompatible.... all bolt holes are at the same spacing... but the new chainring appears to have an approximately 1.5 to 2mm "nub" to the inside of each bolt hole.... just enough to make it not fit on the spider... from what I know both chainrings are LX (as is the crank, 2003 vintage).... do i need to lay off the crack pipe or does shimano have some other wacky sizing issues besides hole spacing?? I wish I had part numbers on the pieces, but I onlhy have a part number for the new chainring (FC-M580).. here is what i got... old chainring says M9 N-32 and across the hole from this it says AE... new chainring M9-S32 and across the hole it says CL on this one it also says SG-X below Shimano...
Any info would be cool... I'm gonna call the LBS on Monday and try to figure this out, but I'm kind of a need to know kind of guy, so I thought I'd ask on here....
FWIW I almost took a Dremel with a grinding wheel on it to the little nubs, but then my better judgement kicked in...
Thanks for the help...
I ran into that putting a salsa or something 38 tooth on my LX 4 bolt cranks,seemed the spider was to big. Ended up filing the spyder and ring alot. OK now.
 

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Discussion Starter · #4 ·
Yeah propritary stuff sucks, but what really sucks is that both my crank and chain rings are shimano... Not only is there LX, XT, XTR, ect.., but then 5 bolt and 4 bolt. ok those two make sense, but then on top of that they offer two different configurations in the 4 bolt (maybe 5 too)... Oh well my LBS ordered me up the new chain ring and I'm getting it tommorow.... Its enough to make a guy go Sram/Truvativ or at least Sram and any of the numerous crank/bb makers...
 
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