Morning, so I currently have a 48/36 Ultegra chainset and a 11-32 cassette on a Ultegra medium cage rear mech. Is there any reason why I can’t fit a 48/31 GRX chainset to give me more chance of getting up stinking steep hills? Thanks, Stuart.

What front mech? Check Shimano.si for tech Doc’s etc

GRX chainline is slightly different to Ultegra so your front mech might struggle.

Another option would be a wider-range cassette. An Ultegra rear mech will handle it, despite what Shimano document.

Another option would be a wider-range cassette.

I believe the Ultegra will handle up to 40T perfectly well with a roadlink. As for the front end, instead of a whole new crankset how about some Absolute Black 46/30 oval chainrings? 30×40 sounds like my kind of gearing!

I believe the Ultra will handle up to 40T perfectly well with a roadlink.

I have 50/34 and 11-40 without a Roadlink. Can’t guarantee that’ll work on all frames though.

Some tips here https://singletrackworld.com/forum/topic/ultegra-6800-smallest-chainrings/

Have a play with different ring sizes and cassette options in a gear inch calculator such as https://www.sheldonbrown.com/gear-calc.html

New inner ring and 11-34 cassette would set you back ~£80 going on Merlin prices.

https://www.probikekit.co.uk/bicycle-cranksets-and-chainrings/shimano-grx-rx600-double-11-speed-chainset/12649530.html isn’t a bad price for a 30/46 chainset, if you don’t mind 175mm cranks.

I have 50/34 and 11-40 without a Roadlink. Can’t guarantee that’ll work on all frames though

This is the way to go if you’re happy to experiment.

What 40t rear cassette are people using with the ultegra rear mech?

As ever, thanks everybody.

Ian, XT 11-40 on mine.

Ian, Sunrace on mine

Although TBF I switched one mech to 105.

Thanks all. So a mtb cassette will just work fine on 11sp ultegra with a road rear mech? (Obviously within limit of chain capacity of cage). Has this always been the case? I thought Shimano cassettes were mtb or road…..

Ian

That’s what I’m using on the Amazon.

105 5800 shifters

105 5800 50/34 chainset

105 5800 front mech

Ultegra RX800 rear mech (I wanted RX for the clutch as I take the Amazon off-road most of the time)

XT M8000 11-40T cassette.

The only “non-standard” thing I’ve had to do is extend the 116 link chain by two links. I can fully cross-chain.

If I remember correctly, depending on your hub, you may need a 1mm spacer behind the cassette.

Not only that, Deore 591 9speed derailleur is a great cheap alternative if you’re struggling to wind up the extra chain, it works with 10 and 11 speed, not sure about 12sp though.

Guys, thats awesome. Thanks!

Ian