Oval Narrow/Wide - anybody got one?

^ Interesting - this seems opposite of what I would expect.

It seems to me that, overall, oval rings would actually improve (reduce) kickback in descending pedal position (pedals level) by increasing the apparent chainring size, thereby decreasing the angle of attack and chain torque on the rear, thereby reducing antisquat and kickback. On the flipside, it would stand to increase antisquat in TDC pedal position, which will depend on the linkage to see if that's good or bad. I can see how this would feel like increased hangup when in TDC, but the increased gear leverage would offset this, no?

Look at the linkage design antisquat curve on the SB-66:
http://linkagedesign.blogspot.com/20...b-66-2012.html (use Google Translate)

Really though, you are talking about 3t of apparent chainring size difference - which should impact antisquat by like less than 5%? - on a linkage that has a pretty neutral antisquat property at 32T avg chainring size.

Also, I think your climbing style matters here. I'm personally a cadence climber - I really like a bit more antisquat and I'm light enough that for me, hangups don't translate into getting stuck, so much as they translate into leverage I can use to maintain sag position (not get too bogged down into the rear tire) on steeper tech climbs. I actually really miss the climbing properties of my SB-66 compared to my current VPP2 Bronson.

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Originally Posted by SchralphMacchio

What didn't you like about it? If no local Utards wanna take that off your hands, I might be willing to buy it off you, if you can drop into an envelope and ship to California.

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I ride a single speed a bunch and tend to stand and pedal when the going gets tough, even on the geared bike. These rings are effective if you're sitting, not so much if you're standing.

I'll let it sit here for a few more weeks as winter in the Wasatch wraps up. If someone doesn't want it, I'll let you know.

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Originally Posted by SchralphMacchio

Also, I think your climbing style matters here. I'm personally a cadence climber - I really like a bit more antisquat and I'm light enough that for me, hangups don't translate into getting stuck, so much as they translate into leverage I can use to maintain sag position (not get too bogged down into the rear tire) on steeper tech climbs. I actually really miss the climbing properties of my SB-66 compared to my current VPP2 Bronson.

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I think this is the biggest difference between how people perceive certain bikes like the Yetis: the new SB's are closer to 100% anti-squat, but the more noticeable characteristic is the tendency to stiffen up on square bumps when climbing, more as a result of the wheel path. Personally, I like it, as the bike gets really efficient and just crawls over, but I can see where the same thing could be seen as locking the rear end or making it less active. (I say that having been probably almost 200 with kit when I was first admiring that "feature." Mostly a style and expectation issue IOW.)

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Originally Posted by SchralphMacchio

^ Interesting - this seems opposite of what I would expect.

It seems to me that, overall, oval rings would actually improve (reduce) kickback in descending pedal position (pedals level) by increasing the apparent chainring size, thereby decreasing the angle of attack and chain torque on the rear, thereby reducing antisquat and kickback. On the flipside, it would stand to increase antisquat in TDC pedal position, which will depend on the linkage to see if that's good or bad. I can see how this would feel like increased hangup when in TDC, but the increased gear leverage would offset this, no?

Look at the linkage design antisquat curve on the SB-66:
http://linkagedesign.blogspot.com/20...b-66-2012.html (use Google Translate)

Really though, you are talking about 3t of apparent chainring size difference - which should impact antisquat by like less than 5%? - on a linkage that has a pretty neutral antisquat property at 32T avg chainring size.

Also, I think your climbing style matters here. I'm personally a cadence climber - I really like a bit more antisquat and I'm light enough that for me, hangups don't translate into getting stuck, so much as they translate into leverage I can use to maintain sag position (not get too bogged down into the rear tire) on steeper tech climbs. I actually really miss the climbing properties of my SB-66 compared to my current VPP2 Bronson.

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5% can be noticeable on a bike, and I've got a pretty smooth cadence. Before the yeti, I rode FSR bikes for about 15 years, and think that they technical climb much better. I'm still on the fence about the yeti, might eventually switch to a specialized stumpjumper evo or enduro if I can find a good frame for under $1000.

I use one, hidden on inner ring of my road bike. I love it for climbing.
I'm to vain to use one on my MTB where it's visible to the naked eye.

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Originally Posted by Dee Hubbs

I use one, hidden on inner ring of my road bike. I love it for climbing.
I'm to vain to use one on my MTB where it's visible to the naked eye.

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What size ring do you use on the roadie? What would you compare to a standard ring ?

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Originally Posted by mcski

What size ring do you use on the roadie? What would you compare to a standard ring ?

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I have a Dura Ace 50-34 matched up to a 11-28 cassette. I live in Colorado and all my rides include climbs and I spend a lot of time in the small ring.
I replaced the 34 with an Absolute Black 34 and I love the smooth cadence and power delivery I get with oval.
On my Di2 bike its really easy to switch between big ring and small ring gears that have the same ratio.
Climbing in 50-19 is ratio 5.2, from here I can easily shift to 34-13 with the same ratio of 5.2. I can usually climb longer on a pitch in the Oval ring in the 34-13 combination then in the big round ring with the same ratio.
Its hard to describe but I can keep my cadence higher and still push the same power. I sound like the marketing lingo, but it feels like a 32T in the climbing aspect and putting the power of a 36down.
I just ordered the parts to upgrade my Di2 system for Synchro Shift, I am going to program 2 models (one identifying the small ring as 34 (actual) and one as a 36. When the bike shifts based on the next ratio request, this will truly show me if the oval is felt or supporting what I feel.
Hope this answered you question.

Awesome detail. Thx!

I'm back to a round front ring, 32t race face with a sunrace 10spd 11-40t. I just like the feel of it and have a pretty smooth round pedal stroke. It also seems to reduce bobbing on my yeti SB66 vs. the oval. I haven't ridden the oval in several months, and have also changed wheels, tires, crank and shoes, so this is certainly not a scientific back to back comparison.

^ new crank, same geometry or new crank and different length, q-factor, or other???

Very interesting result. I really wonder if it's the anti-squat that is impacting your bobbing. But changing the crank geo would certainly invalidate the conclusion.

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Originally Posted by SchralphMacchio

^ new crank, same geometry or new crank and different length, q-factor, or other???

Very interesting result. I really wonder if it's the anti-squat that is impacting your bobbing. But changing the crank geo would certainly invalidate the conclusion.

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Noticeably narrower crank at the same length, stiffer and lighter shoes, clipless. Also running a slightly wider rim with a slightly larger, softer compound rear tire, with a lower pressure - softer overall. Have also changed my rear suspension setup, have removed all volume rings (made it less progressive), increased pressure, reduced sag, increased rebound damping. So that certainly reduces the bobbing. But I do think the round ring helps reduce the bob for me, just a bit, and it feels more natural.

I will be adding some spacers to improve the chainline, so I might just pull the crank anyway to try the oval ring on the new setup, while I fabricate the spacers - custom shape to match the new xtr M980 crank's tabs.

Before the Yeti, I rode FSR DH/Freeride frames for about 15 years, which are far more active under pedaling and are much better in technical climbing, much less anti squat. It's actually much harder to clear certain technical climbs around here on the yeti.

Anti-squat doesn't make a suspension less active (but changing chain length with travel can, and that happens on the Yeti and the FSR in opposite directions). It seems difficult to separate a user's expectations from reality when it comes to movement, though--if you were used to a hard tail I expect you'd find the Yeti to be the easier bike to use in those situations. Having the bike act differently than you expect has more to do with it than fine tuning.

^ yeah I agree there about expectations.

I had a somewhat poor implementation of a horst (Norco Fluid gen 1) that sucked when climbing (squatted like a bad snowboarder trying to ski - oh wait, that's me). Going to the SB-66 seemed like the best climbing machine ever ... loved it more than current VPP2 in seated climbing ability.

Regardless, I still wonder if the conclusions are valid (for whatever reason) about oval rings affecting bob, for better for worse. Can't wait t try one out this summer.

I'm not ready to write off the idea that an oval can make an SB-66 bounce a little, either. My wife runs a small AB on her SB-95 and my impression is that between moving the chain down (it was already below the instant center and therefore contributing to AS>1) and wiggling it up and down there may well be more bob than her 32T round gave. OTOH it's still so minimal that it could also be cadence related if my eyes aren't deceived. All that said, I don't think there's a general conclusion for other bikes there, given the uncommonly high instant center on the old switch design.

I stopped noticing the oval bounce after a dozen or so rides

So I ended up putting my 32t oval back on, my chainline with the 32t round was way off. The oval has spacers built in. Will get to ride it today hopefully.

Also needed to shave down a BB spacer to 1.5mm, to correct for my BB width on the frame being too narrow. When I installed a new M980 crank, I found that the arm was way too close to the chainstay on the drive side due to the layout of the frame and the low q-factor crank. I measured the BB at 71.5mm instead of 73mm, it appears to be short on the drive side. It seems that Yeti uses a removable chainguide related insert on the BB. I put in an extra 2.5mm spacer and crossed my fingers, it seemed to work but the chainline was even more out. Now I have shaved down one of the 2.5mm spacers to 1.5mm (1.53 to 1.57 mm measured actual, which is flatness within +/- .001").

The BB spacer moves the chainline in about 1mm. The oval ring moves it in a bit over 3mm. So I went from a chainline around 50mm, down to 46mm. The chain no longer drops off the largest cog when backpedaling.

I need to order some extra long chainring bolts and fab up some 1/8" AL spacers in order to mount the 32t round in the proper position.

Bump. Made up some spacers and custom modified long bolts to mount my 32t round ring on xtr M980 2x "Trail" cranks. Seems to have resolved the large cog chainline issue to my satisfaction. I definitely prefer the round ring. The 32T oval just feels choppy and harder to turn over. Keep in mind I'm using non-platform clipless and XC race shoes.

for me the oval "chop" is only if my cadence is too high. The oval likes a slower cadence IMO. I love the oval since I don't "stall" at 6/12 o'clock in slow tech situations. For me it's definitely better than a round ring.

I just put on an oval. I was sold a mile in. It shines on high output stuff. Steep technical climbs. Really smooths out energy output. I can see how the high cadence high mileage guys might not appreciate it. Need to be struggling up the kind of thing where it's hard to even steer your bike you're going so slow and jerking your body around.

^^^
Agree with this, I've got about 300 miles so far. I'm a bigger gear kind of guy, not a spinner, to begin with. Very noticeable improvement on steep and/or technical climbing. I'm now on a heavier, longer, slacker bike with more suspension and much less anti-squat, ie. more active. In spite of all that, I'm cleaning more technical climbing moves, and getting further up steep, loose stuff with this setup.

I've got a 34t Rotor Q-Ring with XO1 Eagle 12 speed, 10-50. Rarely use the 50, it's only for 'emergencies'. I think it definitely rewards pushing bigger gears more and spinning high cadence less.

Oval is sweet!

Just re-reading this after a while. I got an AB oval last summer. I like it. Kind-of wish I had a gone 30 instead of 32 tooth. 11/42 in the back. 29 tires.

All the talk of percentages and millimeters cracks me up. Y'all are nerds. Keep it up.

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Originally Posted by eshed

Just re-reading this after a while. I got an AB oval last summer. I like it. Kind-of wish I had a gone 30 instead of 32 tooth. 11/42 in the back. 29 tires.

All the talk of percentages and millimeters cracks me up. Y'all are nerds. Keep it up.

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Agreed on the 30 vs 32, but I'm coping. :-)

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Originally Posted by eshed

Kind-of wish I had a gone 30 instead of 32 tooth. 11/42 in the back. 29 tires.

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Was your previous ring a 30t? I definitely wouldn't recommend going up a size since the gear inches don't change. I'm running 32x11-42 as well but on 26s.

I was coming from 2x10. I did some math and actually did gain a slightly lower gear having a 32-42 than did with 28-36. All my friends said to go 30 but I kept asking around to get somebody to agree with the decision I had already made. Recently I demoed a bike with 30-42 and really felt the difference on sustained climbs. Maybe I just need to bike more. And listen to my friends advice

Ah, shouldn't have assumed you were already coming from 1x. Did you feel over-geared on your 2x setup? It's pretty logical to match your previous low gear if it was working for you.

I'm on 32t oval (x 11-46) and it works awesome for all of our riding near-town and mid-country.

The high-country (our alpine) will eventually dry out, and when it does, I'm gonna want a lower gear

If anyone wants to get rid of a 30t oval (104bcd) please let me know.