Shimano/SRAM Compatibility

+1 for the Sunrace RX11 cassette option.

I have mixed and matched Shimano/SRAM 11spd cassettes on all my bikes without issues in the past, and am currently running a Sunrace RX11 11-32 on one wheelset,  Shimano 105 11-34 on another, and SRAM on a third, swapping all the wheels between Ultegra 6800 on the road bike, and SRAM Force 1x on the CX bike as needed.

I have found no issues with the 11-34 cassette on the Ultegra 6800, despite it being officially limited to a 32 tooth, so I would expect an 11-36 to work fine on an R8000 mech which is rated for a 34 max. sprocket.

FWIW I know that a Sunrace CSRX1 11-36 works fine with an R7000 GS rear derailleur.   CX bike I bought came with 46/36 and 11-28.  I wanted (needed) lower gearing so changed the RD to GS and bought the Sunrace cassette.  No problems at all so far (and I think the Sunrace cassette is lighter than the SRAM one if that matters).

I'll add my two cents worth...

No issues at all mixing 11 speed SRAM and Shimano - Chain Reaction talking bollocks (not unusual).

I agree with fuckawitribe, try the 11-36 before buying an extender. Shimano are always conservative with what they 'say' will work because they won't recommend changing parts that might not be 100% perfect. For example I had an 11-34 10 speed cassette working very well with a short cage Dura Ace 7800 derailleur - B screw was screwed all the way in. I think you'll be fine with the 11-34 and judicious tinkering with the B screw.

I agree with vonhelmet - a smaller inner chainring is needed for proper off-road gravel stuff... unless you are happy walking the steep stuff.

50/34 seems like too big a chainset for a gravel bike. I'd be dropping the chainset for a smaller one, 46/30 as suggested.

Huckfinn wrote:

... Another option would be: keep cassette and simply replace the 34t in the 50-34 crankset with a 32? ...

I’ve read about the possibility of fitting a 33T to a compact chainset, but not a 32. As well as the bolt circle diameter (BCD) of your existing chainset there is also the variable of whatever make and model you currently have (mine, for instance, is a Shimano Ultegra 6750 model). Given that you have a compact chainset and and 11-34 cassette you're just about at the limit of what you can do with your existing rear mech and chainset IMHO.  There may be an option for a rear mech extender and, say, an 11-40 cassette, but it’s a bit hit and miss really. 

"They say, though, that it's not ideal to mix and match Shimano and SRAM parts at the higher 11 speed range..."

They're talking nonsense here, there's no issue whatsoever with using an 11 speed SRAM cassette with a Shimano groupset. It doesn't make a difference if it's at the higher end or not. 

I use 105/Ultegra cassettes with my SRAM Red groupset as they're far cheaper. 

I find this article very handy when it comes to knowing what can be mixed and matched with 11 speed groupsets:

https://cyclingtips.com/2017/12/mixing-road-groupsets-what-works-togethe...

You can't *officially* replace the 34 in the 50/34 with a 32, because Shimano road derailleurs can only handle a drop of 16T (50-34=16). Having said that, it might work fine, possibly just a slower/heavier shift.

The SRAM cassette option will work, as long as your derailleur is the long cage (GS) version - which it should be if you're already running an 11-34 cassette. I thought Shimano already did an 36T cassette option? Announced recently with the GRX groupset?

The other option you have is to swap the chainset for a 46/30 or 48/32 - options from Miche (Graff) and FSA (Tempo Adventure) available will work with your existing front mech, or you can go down the Shimano GRX route which will also require a GRX derailleur. The Graff works with your existing Hollowtech BB but is the most expensive of the three options. I went with the FSA Tempo Adventure.