Shimano XTR Trail M985 Shadow Plus 10 Speed Rear Derailleur

It seems that for the past 5 years, Shimano manages to go from strength to strength with their component lines, bringing out new technology that makes a lot of sense to everyday trail riders. The latest XTR derailleur is no exception and is the latest product to receive an update, with the addition of the "Shadow Plus" feature that plants it firmly into the Trail category for XTR. Whilst otherwise sharing a very similar construction to the M980 Race rear derailleur, the M985 will appeal to riders who frequent technical and choppy terrain and want to get rid of the annoying chain slap that plagues mountain bike drivetrains. If  you don't tend to ride super gnarly terrain and 24 grams are worth saving on your bike, the standard XTR Race derailleur will suit you to a tee. But for those riders who will sell their left leg to reduce chain noise and the chance of derailment, the XTR Shadow Plus is actually a much cheaper alternative.

Like all XTR derailleurs before it, the M985 represents the cutting edge of shifting technology and provides near instantaneous shifts when paired with a Dyna-Sys 10 speed shifter. The latest design uses a longer arm construction to improve the cable pull through its entire range of movement, resulting in a more consistent feel at the lever whether you're at the top or bottom of the cassette. Designed to counteract the forces of up & down chain momentum in rough terrain, the selectable Gold tension switch you will see on the B-Knuckle of the M985 adds a boat-load of spring tension to the pulley cage when flicked into the "ON" position. Acting like a pseudo-chain device, the Shadow Plus design not only keeps the chain from bouncing into your chainstay, it also increases tension around the chainrings resulting in fewer dropped chains compared to a non-Shadow Plus rear derailleur. When flicked into the "OFF" position, it acts like a regular XTR Shadow derailleur and makes removal and installation of the rear wheel easier. Of course for longer travel bikes you'll still be wanting to run a chainguide up front or some sort of retention device, though when used in conjunction with the Shadow Plus design, you will minimise almost any chance of chain derailment.

From Shimano:

"The new 10-speed XTR rear derailleur sees a re-engineered architecture that provides a smooth, linear feel at the shifter and is remarkably stable despite suspension movement, trail chatter or inevitable cable contamination".