What is the difference between GRX RD-RX810 and RD-RX812?

RD-RX810 is a 2x rear derailleur with 34T max cassette for double chainring setups. RD-RX812 is a 1x derailleur with 42T max cassette, designed for single chainring gravel builds with wider cassette range.

Does switching the clutch ON affect shifting performance?

Very slightly — clutch-on adds minor resistance to cage movement which can make shifts feel marginally heavier. In practice the difference is imperceptible at riding speed; the chain stability benefit far outweighs it.

What cassette range works best with this derailleur?

Shimano GRX 11-34T cassette (CS-HG800) is the designed pairing. An 11-32T road cassette also works. Maximum usable cassette is 11-34T; going to 11-36T will cause the chain to contact the spokes.

Shimano

Shimano GRX Rear Derailleur, RD-RX810, 11-Speed (Upto 34T CasSette)

Name: Shimano GRX Rear Derailleur, RD-RX810, 11-Speed (Upto 34T CasSette)
Brand: Shimano
SKU: CMB_WOW_IRDRX810
Price: 9420.00 INR
Availability: InStock
Author: InstaSport Editorial

₹9420.00

Description

Specifications Adjustable chain stabilizer prevents chain slapping and drops Switch stabilizer ON/OFF to match the terrain Gravel-tuned clutch tension Silent and uninterrupted rear shifting on rough terrain Smooth and reliable mixed surface shifting Compatible with current road DUAL CONTROL LEVER Fe