Check out the chainring (second shot in the slideshow)

http://www.vitalmtb.com/photos/features/WINNING-BIKE-Fabien-Barels-Canyon-Strive-CF,8214/Slideshow,0/sspomer,2

That’s mental,

No wonder I’m crap, my chainrings are just round!

he has one leg shorter than the other after a big crash and surgery. The chain ring probably helps him out

grantyboy – Member
he has one leg shorter than the other after a big crash and surgery. The chain ring probably helps him out

Yeah, from the audio, it sounds like he’s all sorts of messed up. Not that it’s slowed him down any.

Looks like the Squoval rings some roadies have used, not just wonky, actualy flat/square in some sections.

Surprised the chain guide has a deep enough cage to cope with that much variation in size!

wonder what sort of difference it makes to the suspension? Might make a big difference to pedal bob etc.?

http://www.osymetricusa.com/

It’s one of these. Looks like off-the-peg in terms of shape, and looks like he’s blacked it out somewhat ineffectually. He’s using a crank “downgrade” (XX1 not XO1) to allow him to use a non-SRAM chainring which probably doesn’t go down brilliantly at SRAM HQ.

Not narrow-wide though – I guess that’s why he needs top and bottom guides. But still not a complete chain device.

Osymetric job isn’t it?

Supposed to make best use of your down stroke on the pedals an provide some relief in the “Deadspots” it basically changes the mechanical advantage the rider has over the drivetrain throughout the pedal stroke…

Barel’s been using wonky rings for years in DH and Enduro due to having a carked knee…

He’s using a crank “downgrade” (XX1 not XO1) to allow him to use a non-SRAM chainring which probably doesn’t go down brilliantly at SRAM HQ.

They’re the same crank, he’s just changed the spider (which is the difference anyway), but yes, it looks like a conventional Osymetric ring. I plan to try one of the Absolute Black narrow/wide oval rings when I change mine, as they’re having a bit of resurgence after lurking in the wings for the last few years!

That’s a question actually,

Would an Oval/Squoval type profile effect the efficacy of a N/W teeth and/or Clutch mechs for Chain retention?

edit:

He’s using a crank “downgrade” (XX1 not XO1) to allow him to use a non-SRAM chainring which probably doesn’t go down brilliantly at SRAM HQ.

Doubt they’re too bothered, the XTR pedals are probably more likely to get them in a huff.

I read somewhere that oval rings were quite difficult to make work with 2x and 3x setups on MTBs. I’m not sure why since they seem to manage OK on road bike 2x setups but now that everyone is running 1x, perhaps they’ll make a resurgence.

Oh, and it turns out I got SRAM’s groupset hierarchy mixed up. XX1 is top tier, apparently so there is no downgrade. Ridiculous groupset naming scheme…

I have also read that clutch mechs don’t like oval rings because of constant chain growth / shortening. I don’t know whether this is a barrier.

Do SRAM make pedals?

Superficial – Member
I have also read that clutch mechs don’t like oval rings because of constant chain growth / shortening. I don’t know whether this is a barrier.

Can see how it might affect them a bit – but no different really than chain shortening and lengthening through suspension action

I have also read that clutch mechs don’t like oval rings because of constant chain growth / shortening. I don’t know whether this is a barrier.

Apparently not – there was a video floating round here the other day disproving this. Something like the overall circumference of chainring in touch with the chain remains constant (at least on some designs) – it just goes in-out a bit.

Sort of like this?

http://i.imgur.com/2ZR5k55.gif

I’m not so sure about chainrings though, do you have a link to the video?

The rear mech hardly moves when the cranks are turning, (were talking a couple of mm at the most), all that happens is the distance between the top and bottom of the chain changes with the chainring size. As far as the rear mech is concerned the chain is still going round a ‘X’ tooth ring, whether it’s round or oval.

I have them on my road bike and we sat and watched out of interest, thinking that the rear mech would move too.

I noticed earlier in the year that Rotor Q were making narrow/wide single MTB rings.

I noticed earlier in the year that Rotor Q were making narrow/wide single MTB rings.

Was having a look at these the other day. They need an SRAM XX chainset with a new spider (or Rotor chainset) and with a ring it’s about 125 quid. Nice though and you can tweak the position of the ring.

Thanks to njee20 I’ve just ordered one of the absolute black ones.

Happy to spend your money sir! They even do a green one! I really ought to get one on order.

I’m not so sure about chainrings though, do you have a link to the video?

The chain is I contact with half the chainring (and on a symmetrical chainring half of the total number of teeth) at all times (roughly). The oval used chainring does not cause the rear mech to bob much as there is little if any chain growth.

What does change is the leverage and the take up / release rates of the chain links. The take up and release rates are balanced so for a constant crank speed the chain with accelerate and decelerate. For a constant chain speed it is the cranks that accelerate/decelerate.

Most people’s legs do not spin at a constant rate / power so getting the right ovalisation at the correct angle to the cranks may help. Maybe. Sky think it does and they do science stuff. So it may well. Or it might be snake oil.

Sky think it does and they do science stuff.

Wasn’t it just Wiggo and Froome? I think now it’s just Froome since Wiggins has gone back to DA chainrings (or at least he had at the ToC, not sure what he was using at the Worlds.) Or do the track riders use them too?

Had heard that quite a few riders use them in place of their smaller chainring and keep the big chainring as sponsor approved. Not sure how much truth there is to that.

Anyway had a ride on a friends bike a few weeks ago that had Q rings fitted and felt really good going uphill. As a result I went out and brought a set for the TT bike. Have had a couple of training rides so far and I like them. Feel they help with fatigue when pushing hard on inclines (probably because of the lower gearing in the dead spot.) Curious to give them a go on the xc bike now.

Time to buy shares in Osymetric….

Meh, bit late I reckon, as Wiggins was usingm them in his peak of popularity, and I suspect all the wannabe TdF winners are more likely to rush out and buy performance!

Am I missing something? Why hasn’t everyone for one of these chainrings? I guess everyone would be more powerful so therefore as powerful as each other. Or something like that

Because the science is a bit vague on the real benefit.

I remember when the oval rings were all the rage in the late 80s/early 90s. IIRC they went out of fashion because a) the science behind the actual benefits was somewhat less than rigorous (as mentioned above), but also b) it was decided that they were actually bad for your knees.

Any truth in this (particularly the bad for your knees bit)?

No, because modern oval rings are the right way round, Biopace were wrong by 90 degrees.

I rode with one of these http://www.mountainbikecomponents.co.uk/items.asp?CategoryID=440&Name=Goldtec+OneKey+Rings on my Alfine’d bike several years back but TBH I couldn’t notice any difference.

wonder what sort of difference it makes to the suspension? Might make a big difference to pedal bob etc.?

Good question. Hopehully the haterz from the maverick thread yesterday will come along soon and explain why it will/won’t. And what will happen if you fit one to an ml7. 😆

Ridea do N/W “oval” chainrings