SHADOW DESIGN FIRST VISITED ON 08 DEOREXT
R. Cunningham
In a departure from its usual XTR trickle down technology mode, Shimano upgraded the premier racing group using innovations from its second-tier Deore XT outfit. The Shadow XTR rear derailleur (literally, the XTR version has a Carbon fiber jockey cage) is a carbon copy of the 2008 Deore XT item.
WHAT’S NEW?
Shimano made a significant departure from its proven dual-spring rear derailleur technology with the 2008 Deore XT group. The B tension function, the opposing spring that allowed for the upper derailleur to swing forward, has been gone. It has been replaced by a trailing link between the frame of the derailleur and the body. This trailing link, which swings between the frame & derailleur body, reportedly allows the entire derailleur to drop down when the jockey cage is overloaded during downshifts. The pivot of the Jockey cage has been moved to the right. This allows the upper pulley to ride closer to the cassette cogs. The jockey cage pivot is now in the center of the upper pulley. The derailleurs parallelogram is angled so that the cassette profile is traced. To keep the carbon fiber jockey cages tension spring in control on bumpy ground, a new cable routing has been implemented to eliminate the looped Shimano derailleurs housing.
WHICH CHANGES?
The redesign aims to move the rear derailleur closer into the frame to prevent it from getting banged up and to keep it smacking the lower parts of Horst-link dropouts. Shimano claims that the Shadow derailleur, RD-M972, is nearly half an inch narrower than the two previous XTR rear changers. The Shadow derailleur is targeted at the cross-country trail rider. Shimano claims that the Shadow provides more precise shifting feedback, which is something many riders have requested.
WHAT SAYS WE?
A closer look at Shadow’s design reveals that the compromise for a concentric-pivoting top jockey pulley is the longer cage. The Shadow’s shorter cage is approximately the same length as the XTR. We have now taken three of SRAM’s carbon fiber X.O jockey boxes and are well aware of the 22-gram weight saving that a cardboard box can offer over an aluminum item. SRAM has updated their 2008 cages with an aluminium inner plate and has rethought its carbon strategy. Shimano’s carbon technology is superior, but it is still true that carbon breaksaluminum bends and the cage is not sticking out where it can hit everything.
Other than these concerns, Shimanos Shadow looks great as a shifting hardware piece and we can admit that it is a better-looking, more practical design than the Speed-Racer X. We think a titanium cage might be in the works.
WHAT IS ON THE HORIZON?
SRAM has switched to a concentric upper-pivot its X.O rear derailleurs jockey box. This seemingly minor change has one advantage: it increases rigidity, and thus places the upper pulley (the one doing the shifting) under each cog more accurately. However, SRAM and Shimano customers are not reporting any improvement in rear shifting performance at the moment. Can you say TEN SPEEDS? If I was in the cross-country pits, I’d be counting cogs at this moment. Only Shadow knows.
SHIMANOS OFFICIAL STATS:
Shimano Shadow XTR Rear Derailleur RD-M972SGS / M972GX:
Low profile design by -Shimano Shadow
Weight savings of -22 grams over M970/M971 SGS
Positive shift feedback is provided by a main body spring with a higher tension
Redesigned bracket axle assembly prevents derailleur contact with the chainstay
-180g mid-cage / 182g long-cage
-MSRP: To be finalized
Available: September 2007
-Will be an addition to the existing XTR rear derailleurs
