As usual, the folks at Universal Cycle are wonderful to work with. There are many sources for Shimano parts, but I spend my money at Universal. One reason is the accurate Shimano part numbers used on the website, so that I know exactly what I’m getting.
I upgraded a China market Giant XTC C2 composite frame MTB with 27-speed Shimano Deore group components to the 30-speed Deore XT group.
For those considering Deore, it’s a great drivetrain that will provide you with trouble-free performance.
But having said that, after you try Shimano’s mid-range groups like Deore XT (and 105), you’ll really appreciate the enhanced shift quality.
Deore XT is great. But I can’t understand why Shimano went to 10-speeds for MTB. It’s ridiculous. The 9-speed cassette was more than adequate (and many will agree with me that the 8-speed cassette was even better for MTB).
Deore XT includes the widely acclaimed Shadow “Plus” rear derailleur. Inside the Shadow Plus derailleur is a spring-loaded one-way ratchet gear surrounded by a band-clamp. When the Shadow Plus switch is in the off position, the derailleur' reacts like any other with a spring-loaded lower pulley cage. However with the switch in the on position, the clamp tightens, engaging the ratchet. The gear wants to ‘ratchet’ backwards freely, but it must pull against the band-clamp, which acts as a sort of clutch to prevent the pulley cage from moving forward. It can move forward, but it takes a considerable amount of force. The design results in an almost fixed lower pulley cage which prevents the chain from slapping the chainstay or bouncing off the front chainring.
Again, I was completely satisfied with 9 speeds, but from 2010 Shimano has evolved Deore XT into a 10-speed groupset. My concern in upgrading from the original 9-speed Deore to the current 10-speed Deore XT was losing some top-end speed. The current 10-speed Deore XT chainwheel for MTB isn’t available with a 44 tooth large chainring (My original is 22-32-44). Shimano forces you over to a 42 tooth chainring with the FC-M780 (24-32-42).
Shimano does offer a 22-32-44 version of the FC-X781 series chainwheel, but it’s for trekking (the FC-T781). I wanted one intended for MTB, so I didn’t choose it.
Heading on the streets to and from the countryside, I appreciated the higher top end speed of the 9-speed Deore owing to the 44 tooth large chainring). I’m a bit unhappy due to the noticeable loss of high-end speed.
I was able to retain my bike’s low-end characteristics. I compensated for the new larger 24 tooth small chainring by going from a 32 tooth cassette sprocket to a 34.
With my new Deore XT cassette, the smallest sprocket remains 11 tooth.
FYI: Shimano claims the smaller large chainring (42T rather than 44T) and larger small chainring (24T rather than 22T) reduces the number of 'recovery shifts' needed at the rear when changing at the front, making it easier to maintain your pedaling cadence.
Shift lever: SL-M590 ? SL-M780
Lower bracket: SM-BB51 ? SM-BB70
Front chainwheel: FC-M590 (175mm, 22-32-44) ? FC-M780 (175mm, 24-32-42)
Front derailleur: FD-M591 ? FD-M781
Rear derailleur: RD-M591-SGS ? RD-M786-SGS (long length cage – max. sprocket 36 teeth)
Cassette: 9spd CS-HG61-9 (11-32) ? 10spd CS-M771-10 (11-34)
Chain: CN-HG53 ? CN-HG94
I didn’t realize that Shimano’s MTB chainwheels like the FC-M590 include a bottom bracket. Shimano’s road group chainwheels do not. (so now I have an extra one, but I’ll use it someday).
NoneWould Buy Again:
July 08, 2014Reviewed by:
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