a mate of mine wants to go single ring up front so i’ve recommended he switch the 38/26 rings he currently has to either a 32/34t ring

he asked if he can get a 30t on there but i’m not sure if it will work

his cranks are shimano deores (dual ring setup) so they’re 104 bcd
but i suspect a 30t ring may not fit due to the size of the ring

can anyone clarify/confirm this please?

Will be fine. The 30t rings are offset slightly to allow chain clearance on the spider. The female part of the bolt is built into this offset part.

They do fit. The nuts are machined into the ring to save the space needed for separate nuts.

I was running a 30T on my 104BCD XT cranks without issue. The smaller rings normally have a thread for the chain ring bolt to screw directly into so you don’t need the 2-piece bolts.

I’m running a 30T NW ring on 104BCD – the ring has tabs to keep it away from the crank arms. The bolt holes in the ring are threaded so you’ll need bolts to fit.

i suspected that there would be chain clearance issues but what you’ve all said seems to make sense
thanks for the info folks.

32t oval betterer. Should also be threaded.

Superstar do a 30t 104bcd.

+1 will work fine

+1 oval betterer.

30T Hope ring on previous generation XT cranks here.

The ring is slightly offset to allow chain clearance, so it’ll fit.

+1 will work fine

+1 oval betterer.

+1 for both…

+1 will work fine

+ another 1
Superstar 30t and uberbike 30t both working fine on 104 cranks

+1 oval betterer.

Well, yes maybe/maybe not. 32t is the smallest oval that you can fit on a 104BCD crank. With this, you’re effectively turning a 30t during the dead-spots and a 34t during the power bit.
I found that the “34t effective” bit was just too much with a 11-40 and I’d be off and pushing too often. Swapped to a 30t round and that’s seams better for me.

I do have a direct mount 30t oval on another bike, with a SRAM crankset. That’s working really well with 10-42.

When the big XT cassettes finally land (is it 11-46?) then a 32t oval will probably be spot-on.