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Discussion Starter · #1 ·
i have a new bike, built up from a frame only purchase. i've put a 28 tooth oval ring with a 11 sp drivetrain, 11-46 shimano cassette.

it works well. however, i know i'm in the minority of guys running 11 speed shimano anymore and i was curious. so i asked Commencal if my bike was supposed to be running (or was designed around) any specific chainring.

they responded to me in an email the following:

We would recommend a chainring of 32 - 34 tooth for the best suspension kinematics.

so i guess i'm doing it wrong. what are the repercussions? i gather my bike doesn't work the way it's supposed to?
 

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‘Wrong’ is what doesn’t work for you. For climbing I need all the help I can get so on my 32lb FS has a 9-46 cassette with a 26t oval chainring. Then my 27lb HT has a 11-42 cassette with a 30t chainring. That’s what works for my fitness ability and terrain. My 32t chainring sits the bench.
 

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'Wrong' is what doesn't work for you. For climbing I need all the help I can get so on my 32lb FS has a 9-46 cassette with a 26t oval chainring. Then my 27lb HT has a 11-42 cassette with a 30t chainring. That's what works for my fitness ability and terrain. My 32t chainring sits the bench.
OP isn't talking about how hard the gears are to pedal. its how the chain forces interact with the suspension. for a demonstration, try riding a single pivot bike with a triple chainset, notice how the suspension performs differently in the 3 different rings its to do with where the chain is in relation to the pivot point, be it above, below or in line with it. IME oval chainrings really make single pivot full suss feel weird on tech climbs, especially in low gears.

OP, give a round 32 a go, see if it makes the suspension feel any different, you may like the difference, you may not. If you don't like it, you aren't going to break your bike by running it as you are, but the designers think it works best with 32-34t
 

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There are generally certain anti-squat numbers for every bike in each front and rear gear combo. Generally (and I mean generally!), the anti-squat numbers go higher with a smaller chainring. What that means is that your suspension could be harsher then it needs to be and moving to a 32 or 34 would reduce those anti-squat numbers and make the bike feel a little plusher.

However, it might also be such a small change that you don't feel it! Check out this site and find the anti-squat numbers for your bike:

Linkage Design
 

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I didn't understand it at the time but on my previous Yeti 5.5 when I swapped to a 12 speed I was able to push a 32T whereas with the previous 11 speed I was using an old 28 tooth. The suspension performed much better and iit was noticeable. The bike seemed to pedal much better and not get hung up the sane. To me this alone justified the new 12 dpeed.

Sent from my SM-G892A using Tapatalk
 

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Discussion Starter · #6 ·
i've told them what i'm running after they send their response, i'm curious as to what they will tell me as a follow up.
it's a new Commencal Meta TR frame with DPX2 shock. i don't find it harsh, the suspension and pedalling is excellent. i do use the shock switch often, always on climbs. either way, i've put a lot of coin into this new build, i won't be getting a new drive train anytime soon!
 

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I wouldn't stress over it, really. Just enjoy riding it. If you get a chance, put a 32 in the front and see if you can even tell. You might even be able to borrow one. If you try it and don't think the small suspension performance gain is worth it (or even noticeable), then put the 28 back on and be happy.
 

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It makes no difference is you're not pedaling. With a smaller ring there is more anti squat which makes it pedal better, and as a consequently somewhat harsher when pedaling with force. The effect is normally pretty small compared to having the right gearing for your ride.
 

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Chainring size does make a difference is suspension behavior when pedaling in any bike I have owned, though some more than others.

On my single pivot bikes, 4t would make a difference (32 vs 36 ring). Same with my DW link bikes.

My primary reason for converting my 5-spot from 2x9 (24/32 x 11-34) to 1x11 (32 x 11-46) was because I hated how much the rear end hung up on big bumps in the small ring).

OTOH, on some bikes I’ve ridden (such as a friends FSR from the early 2000s and my 2004 Azonic Saber.... both Horst Link designs), the difference between chainrings of different sizes was not that noticeable.

Almost all bikes that I have tried built since ~2010 have had more anti squat than I like, so if anything I am inclined to want a larger chainring than recommended, not smaller.

But that is just me. If you are happy with the 28t, go with it.
 

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My personal observation is that chainring sizes seem to impact single-pivot bikes more than linkage driven ones (such as Maestro, VPP, or DW Link). This is the reason why I've always stuck to 32t chainrings.
 

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It makes no difference is you're not pedaling. With a smaller ring there is more anti squat which makes it pedal better, and as a consequently somewhat harsher when pedaling with force. The effect is normally pretty small compared to having the right gearing for your ride.
Yeah, but when you are climbing tech stuff, and want traction, 120+ anti-squat numbers are not very fun. I found I could feel the difference even in my granny ring on my old dw linked bike - and those increased only slightly.
 

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My personal observation is that chainring sizes seem to impact single-pivot bikes more than linkage driven ones (such as Maestro, VPP, or DW Link). This is the reason why I've always stuck to 32t chainrings.
Say what? :eek:ut:
Yes, that is why those things were developed, to offer consistent performance in multiple front ring sizes (ie, back when triple chain rings ruled). In many ways, they are not needed now as the single ring allows the manufacturer to just have to deal with a single ring.
 

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You NEED the new 10-88t 19 speed drivetrain. It doesn't work very well yet and weighs 3x as much, but you absolutely can't have fun without it. Now go spend some money!
Just wait till the offer 24 speed drivetrains and eventually 36 speed drivetrains.
 
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