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Shimano GRX RD-RX400 10-Speed Rear Derailleur Shimano GRX RD-RX400 10-Speed Rear Derailleur
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GRX RD-RX400 10-Speed Rear Derailleur

Mfg PartNum:IRDRX400
  (6 customer reviews)
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The Shimano GRX RD-RX400 10-speed rear derailleur keeps shifting silent and uninterrupted when riding on rough terrain.

With an integrated chain stabilizer mechanism, the SHIMANO GRX derailleur provides a quieter experience and shifting security and precision on mixed terrain. For rides on smooth surfaces, the derailleur features and ON/OFF switch for the chain tensioner.

  • Smooth and reliable mixed surface shifting
  • Silent and uninterrupted rear shifting on rough terrain
  • Shadow RD+ chain stabilizer prevents chain slapping and drops
  • The gravel-tuned clutch tension helps to provide smooth and reliable mixed surface shifting
  • Stabilizer can be turned on/off to match terrain
  • Compatible with Shimano 10-speed road Dual Control Levers
  • Compatible with current 10s road Dual Control Lever
  • Wide range front gearing — Maximum front T difference: 16T
  • Top sprocket: Max. 11T/Min. 11T
  • Low sprocket: Max. 36T/Min. 32T
  • Total capacity: 41T

  • B-Stock - This product has one or more B-Stock units available. These units can be purchased at a discount (see option select). B-Stock units were returned from other customers and may have missing or damaged packaging materials. These units are otherwise as new. The full manufacturer warranty applies. Click Here for more information.


    Mfg PartNum: IRDRX400 

    Ordered by Most Relevant First
    5 stars
    4 stars
    3 stars
    2 stars
    1 stars
    The GRX RD-RX400 is perfect upgrade for any intro-level gravel bike.
    by flemishcap4745
    Cycling Enthusiast
    Durango, CO

    This rear derailleur performed exactly as I expected. Smooth shifting with a gravel tuned clutch tension for off road or bumpy terrain. I also chose to upgrade my rear cassette from a 11-34T to a 11-40T, and the GRX-RX400 did not require any type of extension link. It continues to perform flawlessly and I've decided to now convert my entire drivetrain to a GRX RD-RX400 10-SPEED group set. One other note, unlike other venders Western Bike Works is well stocked and when I order the item ships immediately and I never find myself on hold waiting for back ordered items to arrive in the distant future.

    Reviewed 5/13/2021
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    Major upgrade from Tiagra RD for gravel use
    by Anonymous
    Cycling Enthusiast
    Pasadena, CA

    Never quite felt like the Tiagra RD was suitable for rough gravel use (fallen chain, choppy shifting on climbs and descents). Very pleased that Shimano didn't overlook 10-speed bikes when they released their GRX components. The clutch system on the GRX RD is really amazing at reducing the chain slap (though at the expense of slightly less crisp shifting... but can always turn off the clutch for riding on smooth roads). On top of that I was able to put on a larger cassette to make climbing on gravel easier. The recommended max 11-36 cassette combined with my bike's 32/48 crankset gives me pretty much the exact range I need.

    Reviewed 8/19/2020
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    Great Features, Great Price
    by Rich
    Competitive Racer
    Washington DC

    I refreshed some drivetrain components after a few thousand miles of commuting, gravel, and CX racing. This paired really well with Tiagra 4700 shifters, and gave more crisp shifting than the RD-4700 that it replaced. I had a couple of chain drops last CX season (but this is a commuter bike with a 50/39 crank), so I'm hoping the clutch will prevent drops in the future. A couple of online reviews mentioned that this will also work with some 11-sp shifters, but YMMV. Highly recommend!

    Reviewed 1/31/2023
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    Compatibility issues, despite advertisement
    by Glyndwr
    Cycling Enthusiast
    Philadelphia, PA

    The derailleur seemed to be a well-manufactured product , and I can't say it doesn't function properly with the correct shifters (perhaps MTB-style trigger or grip shifters?). However, everything I read from users and from the Shimano website suggested this could be used with road shifters, like 105, Ultegra or Dura-Ace. Unfortunately the cable pull of the shifter didn't match up correctly with that needed for the derailleur to travel properly from cog to cog, and the shifts were sloppy.

    Reviewed 3/17/2022
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    So far, so good
    by Anonymous

    Bought to try out GRX gearing to prepare for a new bike build. Used the RX400 as it's on a rebuilt 90s Trek frame that can only fit 10-sp cassette. Was not compatible with my Microshift shifters, so had to buy Tiagra 4700s which work perfectly. Used a couple hundred miles and so far shifts smoothly with no chain drops

    Reviewed 8/1/2022
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    Not compatible with older 10sp shifters
    by Anonymous
    4 of 5 customers found this review helpful.

    This is a great med long cage derailer. Shimano says max 36 tooth, but it seems to be working fine on a 2x system with 42 max cog. Thing to note this is shimano's new shift ratio, so grx shifters or new tiagra shifters are required, older 10speed shifters do not work.

    Reviewed 6/19/2020
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