I dropped from a 34 to a 32t for Leadville on my Supercaliber. In the 10T there was too much slack in the chain after the switch. It was “rideable” but it clearly didn’t look right with that much slack and I ended up taking out a couple of links. I haven’t tried going back to the 34T yet, so not sure if the shortened chain would still work with it, but my guess is it will be ok.
It will be fine for sure
On my Epic Evo with is doing double duty as trail and XCM bike I run a 30t chainring (the smallest ring compatible with the XX1 PM) and a Ingrid 10-48 cassette.
I run a 32/10-52 Eagle on my Enduro and really hate the huge jump to the granny gear. Given that the long-travel sled is no climbing prodigy I can tolerate that but the Evo is a goat-like creature when the terrain goes up. So I opted for a cassette with smaller jumps what made it necessary to size down in the front as well - I am a tiny guy plateauing at 3,5 w/kg. The 30t is ok under most conditions but I spin out when the road turns flat - a case I can easily avoid around here 
What year Epic Evo?
My bike came with a 32t chain ring, and in the 10x32 combination, there’s hardly a gap between the chain and the OEM chain stay protector. Would love to have the option of putting on 30t chain ring for days with multiple 20% climbs. Have been afraid it could end up acting as a chainsaw to my chainstay 
That’s interesting.
I used a mountain bike with a 10–42 cassette and a 28-tooth chain ring, and the only gap that I did not appreciate was from the 12- to the 10-tooth cog.
My current mountain bike has a 11-46 Shimano XT cassette with a bailout gear, and I don’t mind that at all. If I had to choose between a smaller chain ring and a larger gap between the easiest two gears, I’d always go for the latter.
It’s a medium-sized Evo MY 2021 and although it is tight there is no „chainsaw effect“.
Thanks! I might jus get a 30t and test it out! Would transform Z2 rides in steep terrain.
Yeah. The 10-51 cassette. I would definetly want to run a 48 tokth chainring in the front. My smallest gearing ahs been a 36-34 on my gravel bike and that feels kind lf okay, I can get up the climb (although with some issues sometimes). However I feel like 48/51 is plenty big enough for my own needs… I might run a 44 if I’d encounter any steep terrain lr even a 40 with that cassette if there is really steep terrain but why a 38 tooth ks the biggest even on a 2x ks weird to me…?
Oh no! Sounds like 2x is better for your frame, because you would never be running the chain in the small chainring and small cog. So idk
I think not NEARLY big enough for XC. (Edit, not big enough on the rear, small enough on the front)
I run 10/52 in the rear and either a 32 or a 34 in the front on my XC bike currently, but that is with a lot of climbing. That’s at ~ 4w/Kg.
There isn’t a scenario I could ever see myself needing larger than 38 on that bike.
I’m going to second that. I have a 34:46 (I’m on an 11-speed drivetrain), and that isn’t enough to comfortably climb steeper grades at a similar W/kh. On the other hand, spinning out a 34:10 gear at 45+ km/h is more than enough.
With 10/52 I’m doing the exact same thing. For normal days I’ll run a 34t, but for mega days like Leadville will put on the 32T.
Same here, leadville is the only race of the year that gets the 32. 34 for everything else. The only exception is that I’ll run a 38 leading into leadville because I’m doing a bunch of training on the road with my MTB.
Id say if the question is training gear, go big.
If its race day its 1st frame specific, 2nd course specific.
1st is because if your bikes antisquat is low, less than 100%, its going to suck watts with a bigger ring (unless you can lockout the shock). On a short travel bike you wont feel the bob, but repeated climbs and accelerations will start to feel like you’ve got a heavy tire on - that slow burn you hardly notice till the second lap. Avoid it by going with a ring to maximize AS value
2’nd is course. I like the biggest ring I can still push comfortably up the climbs so I cam open up on the descents, especially open ones where you can push a big gear and hit warp 10 where its scary and moat are coasting. Its just kore fun.
I am upgrading my drive train from SRAM NX 32T with a 11-50… to Shimano XT 34T with a 10-51
gear ration on the lowest 4 gears are nearly identical… actually 2nd gear on both setups is 0.76 (32-42 vs 34-45)
Given the same gear ratio, will a larger chainring be any harder to pedal? Or be more efficient?
or is it one of those things that regardless of chain ring size… since the gear ratio is the same then the power required and/or efficiency is the same?
I’m on Sram, but I went from a 32 by 10-50 to a 34 by 10-52 and I couldn’t tell the difference on the climbs. I was just spinning out and needed a bit more with the 34 front chainring.
34 works well for me on the East Coast, but I haven’t gone up any further than that.