Shimano XTR Shadow+ Derailleur = Tested

Online, July 24, 2012 (Newswire.com) - I have been testing the Shimano XTR shadow+ rear derailleur for some time now. This derailleur harnesses some quality technology. The real question is "Is it worth 250 big ones ?"

Shimano XTR Shadow+ Rear Derailleur

From Shimano:
"A new addition to the SHIMANO XTR Dyna-Sys drive train is the RD-M985 SHADOW PLUS rear derailleur. It features a switch at the pulley cage to enforce a heavierspring tension and activate a friction stabilizer to counteract the forces of up and down chain momentum in rough terrain. Chain bouncing can often cause noise as the chain slaps the top and bottom of the chain stay, or even derail from the front chain ring in extreme circumstances. The switch when selected to the "ON" position dampens the cage and consequent chain movement for a nearly silent and stable riding experience. In the "OFF" position it eases the installation and removal of the rear wheel by relaxing the spring tension of the cage"

My Take
Shimano accurately describes the derailleur and it's intended purpose. I have been a 1x & 2x rider for some time now, and always have chosen a chain guide device to help reduce dropped chains. An Ibis Mojo HD frame showed up at the shop a few months ago. With everything ready to build 'er up, except the appropriate chain guide, this was my chance. I quickly opted to test out the new Shimano XTR 985 Shadow+ Derailleur.

Installation: The derailleur was quite simple to set up. Limits, body adjustment, chain routing, and turning it "ON". There is an On/Off which is primarily used to remove/replace the rear wheel. The only tricky adjustment was the adjustable tension of the derailleur arm (will describe later).

Ride Quality: Once installed, and checked over, I put the RD-M985+ derailleur through the paces: Trips up and down Black Mountain Trail, Bennett Gap, Farlow Gap, Avery Creek, Squirrel Gap, and many other classics in Pisgah National Forest. My goal was to rock, rattle, or wack the chain off of either chain ring. The chain never dropped, and there was a tremendous reduction in chain slap. The derailleur responded the way Shimano designed it to. Not only does the RD-M985+ derailleur keep adequate tension on your chain, but it aids in a "positive" shift feeling, by adding a bit of clean resistance to the shift lever.

Cons: With all great products comes hidden burdens. In the XTR Shadow+ derailleur, the burden is the cost of replacement parts. After a month or two of riding, "The Pisgah", your bike and components take a beating. In my case, the rear derailleur took a stick perfectly inserted into the derailleur cage and pulley wheel. This unintentional consequence, of riding, exploded the carbon derailleur cage. OUCH! After a phone call to my Shimano Rep, I was able to replace one for a hefty penny, actually several thousand. As of now, there is no alloy replacement option. Kind of a bummer. I love carbon, but the weight savings is minimal vs. strength.

The last issue that was a bit tricky was the arm tension. When my replacement cage showed up, I decided to break down the derailleur and explore its inner workings. As the derailleur became worn, the spring tension became a little low. So I decided to turn up the resistance on the derailleur, which is easy. After removing a few small screws, you use the built in tool to turn the tension adjuster knob (see below). Getting the right tension is the tricky part, especially with a full suspension bike. Too much tension equates to a bit much resistance on the shifting and low-speed suspension compliance. Too little and chain slap is quite apparent, again.

Adjuster and tool

Final Thoughts: The Shimano RD-M985 Shadow+ rear derailleur is a crucial piece of equipment. As Press-Fit BB's and frames evolve, chain guide set-ups are becoming harder to use. The 2x system is the new Justin Bieber and not all frames accept chain guides at the BB. This is where the RD-M985 shines. It performs flawlessly when installed and tensioned correctly. There is less resistance than a typical chain guide that deflects the direction of the chain, via pulley or roller. If you are building a new bike and require a 1x/2x/3x chain guide, for you riding style, do not overlook the Shadow+. At $250, it kills two birds with one swipe of the plastic. If you are a Sram person: sorry, it's not compliant. I would love to see an alloy cage version in the future. Carbon has its place, but not on a derailleur cage.