Shimano GRX RD-RX400 RD w/ 11-42 cassette

Yes, but only if you have the GRX 400 shifters.  Not other 10 speed shifters, because it is really an 11 speed RD.

kevinviray8892 wrote:Hi guys. Does anyone have an idea if the GRX-RX400 RD would go well with a 10spd 11-42T cassette? 

dangle wrote:

I wrote more in depth somewhere else (and need to edit it), but I have had pretty good luck with the RX810 with the 11-40 and even the 10-42. The entire range of the 11-40 is flawless. The Roadlink DM made the shifting between the 36 and 42 (on the 10-42) cassette super smooth, but left a lot to be desired between the 10 and 12. I ended up ditching the Roadlink DM and going back to the stock guide pulley to get relatively good shifting at both ends. Sometimes it hesitates going from 12 to 10 and occasionally I hear some rumble going from the 42 to 36, but I'm pretty happy. Typically if I'm shifting off the 42, it's multiple gears since I just crested something so that's sort of a non-factor.

I threw an 11-42 from my wife's bike on without any adjustments and it shifts slightly better on each end (in the stand), so that's a good choice if a bit less top end is needed. 

John wrote:

Who makes an Shimano (11x) compatible10-42? SRAM?

John-  SRAM makes the 10-42 cassette.  SRAM and Shimano have the same spacing and are compatible.  The 10-42 will need an XD driver hub though.  

John wrote:Here is my experience with the Shimano 11-42 cassette.

Background:  I bought a 2x Cannondale Topstone (46-30) with the intention of upgrading the Cassette to provide a very wide range, as I frequently ride very steep dirt/gravel climbs (12% plus).  My LBS and I agreed that putting on a 11-40 or 42 Cassette would work, providing an awesome range.

Here is the problem, so far -- the 40-42-46 cassette is 1x only and will not provide a full shifting range larger than a 42 front chaining.  Yes, with a Wolftooth and an Ultegra or GRX rear derailleur, I can get the full 11-42 rear range to work with the front 30, but with the front 46, shifting into the rear 32-37-42 gears is not possible.


While using a 46 front with 32-37-42 causes a cross-chaining I always avoid, sometimes situations occur when doing such is not easy, as with rollers.  

In addition, shifting from the 46 front to the front 30 is not smooth and with the lower gear range, double shifting is required.  However, Shimano fine print indicates that a GRX rear derailleur is required with the 11-42 cassette.

Shimano's website is inconsistent and vague regarding GRX mix/match, other than 10/11 speed incompatibility. 

The best solution would be a 42-10, which Shimano does not offer.  SRAM's website is component compatibilities is worse than Shimano, hence my question:

Who makes a Shimano 11 speed compatible 42-10?  I think this would solve all my problems, but I read somewhere that there is a diameter incompatibility with the 10t?

Thanks!

11s Cassette Compatibility:

• 11-32: Not Required (GS medium cage rear derailleur works).
• 11-36: Single or Double Chainring (front rings can be no more than 14 teeth different e.g. 48-34).
• 11-40: Single or Double Chainring (front rings can be no more than 10 teeth different e.g. 46-36).
• 11-42: Not Supported.

Mark_S wrote:No problem.  Good luck with this.  Perhaps just be careful riding with the short chain.  If you're distracted and somehow catch one of the larger cogs while in the 46 you could do a bit of damage.