Single Speed and Oval chainrings….

Thinking about trying an oval chain ring on a SS project.

Question to single speeders who have tried an oval ring – did you keep with the same number of teeth as before, or go up/down? How did you get on?

thanks

I kept with same size (think that is the point with the bigger part in more efficient area)

Went back to a round ring after a few weeks though as couldn’t put up with the constant slack chain/tight chain every revolution of the cranks – I may be a bit anal about chain tension…

Depends how you feel about your gear at the moment. If you’re happy with the speed on the flat, but want to make the hills easier, go for an oval with the same no. of teeth; if you’re happy with getting up the hills, but want a bit more speed on the flat, go up 2T.

I went up 2T. I’ll only go back if Absolute Black stop making them! I love mine.

I went 2 up on mine, but i was thinking of going up a size anyway so effectively stayed the same size.

Love the oval on the SS.

Are you guys on 29ers by any chance?
I went up 2 as the common wisdom and lasted 2 rides on my 26″. Thought maybe I’d keep it on for ‘training’ then realised I was avoiding all the steep hills. Went back to round.

One of mine is on a 26er. 35×17. 1st gear I put on it and it works for me. Never had round to compare it to.

thanks for the info. 26er here. Mainly interested if it benefits really low rpm on the steep hills (out of the saddle)

Intrigued by this.

Lost a chainring bolt (one of four) recently but didn’t notice for a week or two and only suspected something was up when the chain tension felt different mid pedal rev. Went to put a new bolt in but noticed the chainring (a Surly steel one) and crank tab no longer lined up and the affected quarter of the ring had begun turning itself into an oval.

Bashed it back into shape with a length of chain and a hammer and got the holes aligned again but it made me wonder if that indicated an oval would naturally be the best shape?

What concerns me is the slackening/tensioning of the chain, but only if it’s going to make dropping the chain more likely. Not bothered what it looks like. What’s the received wisdom?

This is on my 29er XC race bike.

Surely if your chain is going slack with an oval ring it is because it’s poorly made. Maybe name the ring.

The same number of teeth are engaged at any part of the revolution.

Will not true SS I run with a Alfine and an oval without a problem, hardly any change in chain tension.
Went down to a 32 from a 34 round as I wanted a lower gear. I didn’t notice the difference until I jumped on my road bike, that was a strange ride!

Cheers, Steve

On the advice of Taz I went up 1 tooth. Didn’t notice a difference. I wouldn’t use a round ring on the ss again.

Will not true SS I run

While even….. 🙄

Cheers, Steve

The advantages of an oval ring are supposed to be smoothing out the stroke and minimising the dead spot in a pedal revolution. The theory is this leads to a reduction in fatigue more than anything… pedal smoother, last longer 😉 Rotor’s own research in to this concluded that there were no statistically significant benefits to using an oval ring but equally there were no negative findings either. So, give them a try was what they said. Entrepreneurial companies have gotten them back in the limelight again 😉

Went back to a round ring after a few weeks though as couldn’t put up with the constant slack chain/tight chain every revolution of the cranks – I may be a bit anal about chain tension…

Same here. In practice the chain is *probably* unlikely to fall off but my mind couldn’t rest with the floppiness of the slack sections

Surely if your chain is going slack with an oval ring it is because it’s poorly made.

That isn’t true. If that was the case then how can you have an effective 30t effect in the dead spots and an effective 34t effect in the “power” zone on a 32t for example? The section that the chain contacts isn’t constant but the argument has always been that the difference is *minimal*. If a round ring is slightly out of round then you can see and feel those tight spots, an oval ring is no different.

OP, judge for yourself:

Tight bit looks too tight, slackest section is pretty floppy even though the chain is over tensioned IMO

For balance, here’s Marcin very delicately prodding the chain to show tension remains *even*. The video where they show an oval ring with XX1 and the rear mech bobbing around seems to have been removed

On a geared bike I didn’t see the oval ring as a particular benefit but it also wasn’t any hindrance so I stuck with it. I didn’t notice much difference swapping between round or oval and didn’t find it such a night and day experience as some people, even in terms of feel let alone “performance”.

On a SS I couldn’t let myself trust the slackening of the chain and found a NW ring a bit noisier than the Renthal ring I usually use so there was enough to make me switch back.

Summary, try it and see if you can live with it 🙂 Most companies will exchange for a round ring if you don’t like the oval sso you don’t have anything to lose by trying

didn’t find it such a night and day experience as some people, even in terms of feel let alone “performance”.

I was the same, didn’t notice much change until riding a round ring again.
Didn’t notice any performance gain. Though I would like to try oval on my road bike.

Cheers, Steve

Surely if your chain is going slack with an oval ring it is because it’s poorly made. Maybe name the ring.

The same number of teeth are engaged at any part of the revolution.

In theory yes, if you had 2 oval rings exactly the same size front and back (negating the benefit though). In reality the oval tales up the slack by always engaging the same number of chain links, but the chain isn’t horisontal, so is wrapped round slightly more than half the chaining, which means the tension is never perfect.

That said, I run my chains relatively slack and never have them fall off. Matched chain widths and sprockets see to that (3/32 everything).

Regarding slackness – the slack spots were never slack enough for chain to fall off but it was very noticeably slacker.
I was using Absolute Black as they do a direct mount for my SRAM cranks and unfortunately it only comes in narrow/wide which also make the chain noisier. Not much need for narrow/wide on a single speed.

So additional noise and continual slack/tight chain made it no good to me. I also felt it looked pretty odd too (which is clearly important)