I’ve got a bike with Sram Rival XPLR 13 speed on the way 
and am looking for options for smaller chainrings for big climbing rides.
It looks like Sram and Wolftooth make down to a 38T chainring for the road/gravel 8 bolt cranks and I believe these have a 6mm offset. Could I run a MTB 8 bolt chainring (e.g. 36T 3mm offset) on Rival or Force 8 bolt cranks? I assume they would bolt up OK and would just mean the chain is 3mm further outboard? Has anyone done something similar?
Thanks!
I just got my new bike with 13 speed force, but have a big climbing gravel race this weekend so had them build it up with my MTB cassette and derailleur for now.
I was doing the same as you and looking at chainring options, surprised there aren’t more 36 tooth variants with proper offset. I did see Alugear had some, but decided to wait before pulling the trigger on more money. It sounded like the 3mm offset should work, so for now I bought a cheap one off AliExpress just to test it out and see if I was happy with it.
Having said that, I haven’t installed and tested it yet. It sounded like the different offset shouldn’t be a big deal from what I could find, but would be interested in any other info for sure.
Good luck at the race! Let us know how the set up works.
I was thinking about getting a GX derailleur/Transmission cassette too but am cheap 
I’m not at the pointy end of races so figured a small chainring would be the easiest solution.
I’ve just temporarily stolen the MTB stuff off my mountain bike, so it’ll need to go back on there. And I got an Aliex chainring, so I definitely have some cheap going on myself 
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The mullet worked really well so far but the 13 speed looks like a nice setup, and with a 36 tooth it gives similar range…the easy gear is almost the same as 40/52, and the top gear is equivalent to having an 40/11 instead of a 40/10. So I think the smaller chainring will be a good solution.
Assuming the cheapo version I got works decently, I’ll probably get the alugear option if there are no others that come out.
Bit late to this thread, but I have been using the wolf tooth 36t 8 bolt mountain bike chainring 3mm offset on my Crux, with a Rival Xplr 10-44 12 speed etap axs setup for around 6 months now.
I actually bought it by mistake, I had been looking for a 36t gravel chainring for a while as I live in North Wales and most of my riding is steep mountain bike territory really, and forgot to check offset, just got excited when I saw 36t and 8 bolt direct mount 
only realised it wasn’t correct offset after I had used it for a few months… 
It works fine though, I had to shorten chain and not sure if changing is quite as crisp? but its certainly acceptable, but I will be using the same bike for CX this season and am getting twitchy that the chain line not being quite right will put excess strain on chain etc, especially with the extra strain of stamping on the pedals out of every corner in a race situation, and so am about to purchase the Unite 36t 6mm chainring, out of stock at moment but due back in any time now apparently.
Hope this helps
I’ve used a 3mm offset 36t with my 12spd XPLR derailleur and it was fine. No problems shifting or noticeable extra drag. It basically shifts my chainline out one cog, giving me a 44t extra low gear, but roughly the same ratio neutral gear as my 40t ring.
13spd may be a bit more finicky, but I kind of doubt it.
IDK, but I run a standard (6mm) offset instead of boost (3mm) offset on my MTBs because it favors the larger cogs, which is where I spend the most of my pedaling time.
I ended up running a 36t 3mm offset on my gravel bike for a very climby multi day stage race, and it worked great, zero issues. And to add to that, I have to admit it was the Ali express unit I mentioned above.
