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Replacing the crankset on my Jeffsy (and the bottom bracket) with a Shimano XT, current crankset has an 32T round chainring and I'd like to gear it down slightly for those endless steep lake district climbs at the end of a 5 day trip...
Unite Co chainrings are my choice as they have direct mount ones for Shimano which are also compatible with sram eagle chains. Currently using a 50t Eagle cassette.
I have an option of a 32T oval which should make pedalling easier/more efficient or a 30T round which will just give me a lower, bottom gear.
Haven't used an oval ring before so I'm tempted by that but not sure if it will actually give the same result as a lower gear.
I find steep techy climbs easier with an oval than with the same size round.
Any reason you can't got with a 30 oval have use both advantages?
I've been very impressed with the 32t oval on my Occam, but I swapped from a 32t round. I say get the 32 oval.
I would go 30T oval if I could, but Unite co rings are the only ones that say they're compatible with SRAM chains for the XT 12 speed cranks. And they only do a 32T oval size.
Hmm, Burgtec says their oval is compatible with 10/11/12 speed. Doesn't say SRAM though....
SRAM chain on a Shimano chainring is a mess of info when you try and search for it, because of the extended inner plates on the 12 speed shimano chains.
I went for oneup for Shimano direct mount, works well with Shimano chain, not sure about eagle.
https://uk.oneupcomponents.com/products/switch-shimano
@davros cheers - I'm sure when I spent far too long looking a couple of months back I was having trouble finding rings that explicitly said SRAM compatible. One up is another option the, cheers
Ha I did the same, but I thought it was the Shimano chain that was supposed to be more problematic. Blackspire could be another option.
Oval felt good for me especially on steep hills, but I found it was leading to very sore and achy knees on long and multi day rides. Went back to round and all is well again. Others don't seem to be affected, but I am firmly back in the round camp.
I'm only on 11 speed so this might turn into a school day for me but...
I though shimano 12 speed chains were a pain on some other rings due to the chamfers...
And SRAM flat top chains for road stuff needed specific rings and cassettes.
I went from 32t round to 30t Absolute Black oval on my rigid 29er. Works well for me, especially on the climbs
After a few hours I couldn't detect any difference between normal round and oval.
Have you tried oval rings on that bike before?
I find they're fine on one bike but I really don't like them on another one - and I prefer round on the third.
I'd go 30t round anyway. The oval might not give you enough of a difference.
30T round - 32T oval is still a 32T.
I went back to round from an absolute black oval. I had a round ring on my 2nd, longer travel, bike and found it was actually easier to pedal than the oval. Kept trying yo convince myself otherwise but eventually changed back to round and it was way better.
Check the bike chainstay clearance will take a 34t if you go 32t oval - it’s heading for 34t diameter in one direction and 30t diameter at 90 degrees to that.
32t oval is great on my Bird (just) after it replaced a 32t round.
But for me it didn’t act like I thought it would. It effectively made it easier to spin. So I’d use a lower gear, spin more, go faster. Not a problem with my ex-rugby player (back 5 of the scrum) thighs, but if you’re after a lower gear I’m not sure.
I’m only on 11 speed so this might turn into a school day for me but…
I though shimano 12 speed chains were a pain on some other rings due to the chamfers…
And SRAM flat top chains for road stuff needed specific rings and cassettes.
See absolute black say this on their rings:
Chainring is only compatible with CN-M9100, M8100, M7100 & M6100 Shimano 12spd Hyperglide+ chains. Using other chains may cause chain to drop very easily from the chainring due to thinner than usual teeth.
So I think it's just down to the design of the individual chainring.
TBH I'm looking to lower the gearing to have a 'bailout' gear when the legs say 'no more' so I'm able to keep spinning rather than pushing the pedals round on a steep long climb. So 30T may be more suitable than an Oval.
I've got a 30t round on one bike and a 32t oval on another.
The 30t is better for climbing and grinding up fire roads if that's what you're after.
Teeth count makes a bigger difference than round/oval in my experience.
I’m running an Absolute Black ‘Shimano’ 12 speed HG+ chainring on an XTR 9100 crank, with a SRAM PC-X1 11 speed chain.
I’ve had no problems with it at all.
Round because oval chainrings are placebo?
Show me the evidence...
There's evidence that placebos work.
I do prefer round rings though, all things considered.
I think it depends how you pedal. If you spin in low gears stick with round 30T, if you stay in higher gears and power it up then go oval.
With oval you may also find you need some sort of chain retainer if it starts coming off the chainring on a back pedal.
I have been using Absolute Black oval rings on both my Fatbike and the full bouncer for a few years. Four things to throw in:
1) IMO they only really make a difference on techy climbs, but they really help me on those
2) Absolute Black make separate Shimano direct mount rings for both Shimano hyperglide and the rest. I actually find the standard ring works with both but is slightly noisy with the hyperglide
3) The number of teeth is the number of teeth. 32 oval does not equal 30 round. Absolute Black goes down to 30T Shimano direct mount
4) No I don't work for Absolute Black - just used them for a long time
As others have said, the number of teeth is the number of teeth so you need to go 30t to lower your gearing. I have oval on one bike and round on the other, I don't notice the difference any more when I switch bikes but also can't tell an obvious difference. Really you would have to do back to back testing to be certain but I can't see any downsides to oval rings
Burgtec say their rings will work with Shimano, I checked when I bought one. Wasn't impressed with the ring though, it constantly creaked and came loose on my crank (Hope) - replaced with a Hope and zero noise since. Not the first Burgtec product I've had that's been less tan stellar quality either.
Changed from a round 30T to Unite oval 32T. For me it works, and I seem able to stay off the final cog when climbing that little bit longer, or able to remain seated more comfortably on longer shallow climbs.
Placebo or not, it works for me.
Ageee with the captain re techy climbs, seems to even out the power better than round rings.
I'm on oval burtec ,shame chain shimano 12spd. No issues. Round feels like riding in mud compared to oval