[Closed] Compatibility question

Maybe. It'll work with a 40T.

Is this a trick question? There isn't an XTR 11-42T 11 speed cassette. XTR is 11-40, if you want a 42T you need XT or below.

The RD-RX812 rear derailleur is compatible with mtb cassettes with a 42T low sprocket max.

https://bike.shimano.com/en-US/product/component/grx-11-speed/RD-RX812.html

My bad, it's likely to be an XT cassette, but the question remains the same.

Thanks Thols2. Looks like it should work fine then.

Yep, my Fugio is running GRX 1 x 11 with an 11-42T XT cassette.

Someone one here had it running with the deore 51t didn’t they? Plenty of room

Follow-on question. I think the GRX range falls into Shimano's road range. If I use GRX600 levers could I still use my XT rear derailleur and cassette, or is the cable pull ratio wrong. Would I therefore need one of those in-line adaptors to continue using this derailleur. Thanks again for help.

https://www.bikeradar.com/advice/buyers-guides/a-complete-guide-to-rear-derailleurs/

current generation (10-, 11- and 12-speed) Shimano road and mountain bike components are not inter-compatible with each other because they use different cable pull ratios. For example, you couldn’t use a set of road shifters with a mountain bike rear derailleur.

http://blog.artscyclery.com/science-behind-the-magic/science-behind-the-magic-drivetrain-compatibility/