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ShimanoUltegra RD-RX800 Rear Derailleur


Item # SHI00KS

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  • Gray, Long ($117.99)
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Item # SHI00KS

Ultegra RD-RX800 Rear Derailleur

Outfit your all-road or CX bike with Shimano's Ultegra RD-RX800 Rear Derailleur and enjoy increased chain tension thanks to its mountain bike technology offering better chain management and less noise over rougher roads and gravel. Just like we're accustomed to on its mountain rear derailleurs, a flip of the lever engages and disengages the clutch. When in the on position, the clutch increases the spring force to provide crisp shifting and zero chain slap and is easily flipped off for wheel changes. This is Shimano's first rear derailleur featuring a clutch for drop bar bikes and since it works with both 1x and 2x setups, we feel it's a must-have for gravel and 'cross bikes.

Following in the footsteps of the revamped Dura-Ace and Ultegra groups, this RX derailleur gets its Shadow cage treatment placing it closer to the frame and under the cassette keeping it out of harm's way and less likely to take the brunt of a driveside crash. This also allows the derailleur to move in a much more linear path allowing for shorter throws with less effort. It comes in one cage length, long, which accommodates an 11-34t cassette allowing for a wide range gear ratio when paired with a double without the usual huge jumps between the cogs like on a 1x setup.

Sitting under the Ultegra umbrella means it gets the usual materials and finishes that we expect from a groupset that's just one step from the top. Its weight, smoothness, and durability make it more than capable of racing against the competition on course, or the sun to your campsite for the night on a bikepacking trip.

  • Clutch-equipped Ultegra rear derailleur for cobble, 'cross, and gravel
  • Clutch system improves chain management and silences chain slap
  • Compatibility for both 1x and 2x drivetrains
  • Durable alloy construction handles mud and all-road adventures
  • Long cage accommodates up to a 34t sprocket
  • Works with current Shimano 11-speed road shifter/brake levers
  • Low-profile Shadow design helps avoid damage from impacts or during a crash

Tech Specs
Cage LengthLong
Cassette Range11 - 34t
CompatibilityShimano 11-speed road
Recommended Useroad
Manufacturer Warranty2 years

Actual Weight

Gray, Long

Claimed Weight

Claimed weights are provided by the vendor.

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Actual weights are measured in-house by the Competitive Cyclist team.

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What do you think about this product?



replacing my dura 9100 rear,is that compatible w dura 9100 mechanical group set??thanks

>Rating: 5

Typical Shimano reliability

I've put it through the wringer
True to size

This is the 2nd time I have purchased an Ultegra RX. 1st one was a year ago and used with a Wolf tooth GoatLink 11 on a 1x gravel build. The 11-42 cassette worked flawlessly with the system. So when it came time to upgrade our tandem from 3x10 to 2x11, it was my “go to” for a refined shifting system with extended range. I don’t expect to use the clutch system very often as it won’t see much gravel, but it’s good to have the option on rough roads.

You were able to use an 11-42 with this?

Kevin, yes just use a Wolf tooth