There has been a lot of buzz regarding the friction clutch inside the Shimano XTR Shadow Plus rear derailleur. The one-way clutch runs concentric with the rear derailleur cage pivot and its function is to prevent the chain from becoming slack between the cage and the chainring. The benefit of the Shadow Plus friction clutch is that rough terrain doesn't allow the chain to pull against the rear derailleur cage spring, so the chain stays taught and in control. Some riders claim that the clutch eliminates the need for a roller chain guide, although our experience shows that Shadow Plus is amazing, but not quite up to roller-guide performance.
Why Should I Need To Adjust the Clutch? Shimano understands that some riders will want more chain control than others, so it designed in two adjustments to tune the friction clutch. The first is external - simply rotate the gold-anodized clutch lever between the engaged and disengaged position to reduce friction from the clutch. Should you want more chain control, however, you'll need to open the clutch housing and add tension to the clutch friction band. When you do open it up, you'll be surprised to see that Shimano tucked an adjustment hex-wrench inside the housing. All you need to tune the clutch is one Allen wrench to remove the housing screws - and the following step-by-step guide.
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| Shimano's XTR Shadow Plus rear derailleur is similar to the standard item, with the addition of a friction clutch and housing at the cage pivot. The clutch engages only when the cage swings forward. |
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| The gold anodized aluminum clutch lever is used to release the friction in order to ease wheel removal. The lever can be set anywhere between closed and open. |
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| Step 1 -Remove the three clutch-housing screws. They are shoulder screws, designed to bottom out on the aluminum derailleur chassis to protect the plastic housing. Put the housing and screws in a clean, safe place. |
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| Step 2 -The one-way roller clutch is the larger cylinder at the lower left. The stainless steel band that encircles it is the friction brake. The adjustment wrench is stowed in the housing above the clutch. The friction adjustment nut is visible in the hex end of the tiny wrench. |
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| Step 3 -Pull the tiny wrench out from its stowage place. The wrench is also a structural tension strut that reinforces the clutch mech, so its best to pop it out with the lever in 'off' position. |
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| Step 4 -Use the adjustment wrench to tighten the small hex screw clockwise to add tension to the friction band. A fourth of a turn makes a noticeable difference. Note: I made my adjustments with the clutch tensioned, but It's best to work the nut with the clutch lever in the 'off' position. |
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| Step 5 -How the clutch-lever cam operates: Flipping the gold lever upwards (left) rotates a cam that squeezes the brake band tighter over the clutch cylinder. Rotating the lever downwards (right) takes pressure off the friction band. Shimano intended the lever to be set either 'off 'or 'on,' but the snail-shell design of the cam allows it to remain in position anywhere in between if necessary. |
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| Step 6 -With the clutch lever engaged, swing the cage forward and check that there is smooth but firm resistance. If it is higher than you'd like, remember that you can reduce the friction by relaxing the clutch lever slightly. |
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| Step 7 -Replace the wrench. It snaps into place with the lever in the off position and is retained by plastic grippers on either side of the rectangular cut-out. |
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| Step 8 -Replace the housing and set the housing screws snugly in place (don't over-tighten them please). |
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| Step 9 -Engage the clutch lever and run the rear derailleur through the gears in each chainring combination to check for excessive resistance at the shift lever or poor shifting across the cassette. Use the clutch lever to reduce friction and compare results. Too much clutch friction can make shifting feel notchy. Before you pass judgement, however, give your clutch tune a ride test. Not happy? Pop the housing off and reduce or add tension to the friction band one-fourth turn at a time until the chain stays on over the bumps and your shifting feels Shimano smooth. |
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