There can only be one

Jpez

Banana Split
@Tubbsy sorry if I missed it but did you end up having to piss the oval chain ring off and go back to round?
For any one interested and then I’ll piss off out of @Tubbsy ’s thread an oval chain ring is quite doable as long as it’s clocked to the idler, according to Ben.
A Shitmano crank this can not be done. My RF crank set and many others make this possible so happy days I get to keep my oval which I do like.
 

Tubbsy

will do custom titles for cash
Staff member
A Shitmano crank this can not be done. My RF crank set and many others make this possible so happy days I get to keep my oval which I do like.
Yes, sorry I should have specified that Ben told me about clocking; I couldn't see how it was possible on my XT and so just chucked another ring on.

Interesting to note that Deviate support oval chain rings but Forbidden don't, but I don't know if that's just for more simple messaging or a technical reason.

And no need to piss off out of my PYR, this is Rotorburn and the thread will soon be about climate policy and dog grooming anyway.
 

Dales Cannon

Deleted Banned Moderatuuur
Staff member
Yes, sorry I should have specified that Ben told me about clocking; I couldn't see how it was possible on my XT and so just chucked another ring on.

Interesting to note that Deviate support oval chain rings but Forbidden don't, but I don't know if that's just for more simple messaging or a technical reason.

And no need to piss off out of my PYR, this is Rotorburn and the thread will soon be about climate policy and dog grooming anyway.
I mixed 1.5m3 of stabilised sand yesterday in the mixmaster. I hate civil work. Actually I hate any sort of unpaid work and most paid work.
 

shiny

Go-go-gadget-wrist-thingy
Yes, sorry I should have specified that Ben told me about clocking; I couldn't see how it was possible on my XT and so just chucked another ring on.

Interesting to note that Deviate support oval chain rings but Forbidden don't, but I don't know if that's just for more simple messaging or a technical reason.

And no need to piss off out of my PYR, this is Rotorburn and the thread will soon be about climate policy and dog grooming anyway.
Forbidden support oval but advise some experimentation is needed with the clocking:

https://www.forbiddenbike.com/pages/frequently-asked-questions
 

Jpez

Banana Split
And no need to piss off out of my PYR, this is Rotorburn and the thread will soon be about climate policy and dog grooming anyway.
Yes you’re right. I forgot the normal rules of forums don’t apply here. So can anyone tell me why my cat keeps spraying everywhere?
I don’t have a dog sorry but if it did I’m sure it would have a balding problem.
 

Oddjob

Can hench anywhere any time
Yes you’re right. I forgot the normal rules of forums don’t apply here. So can anyone tell me why my cat keeps spraying everywhere?
I don’t have a dog sorry but if it did I’m sure it would have a balding problem.
Because you haven't put it down and replaced it with a dog?

Sent from my SM-G970F using Tapatalk
 

Tubbsy

will do custom titles for cash
Staff member
Forbidden support oval but advise some experimentation is needed with the clocking:

https://www.forbiddenbike.com/pages/frequently-asked-questions
Right you are, my memory failed me completely..

I thought they were against it in this interview with a bunch of high-pivot manufacturers:


It's a good little article for anyone interested in these types of bikes.


However I don't really understand how an oval ring will do its job properly if rotated; I thought the whole point was that the oval needs to be in sync with your pedal stroke? Or am I being thick here? Maybe a direct mount ring can be adjusted in small increments, I've never used one though.
 

beeb

beebenson
Right you are, my memory failed me completely..

I thought they were against it in this interview with a bunch of high-pivot manufacturers:


It's a good little article for anyone interested in these types of bikes.


However I don't really understand how an oval ring will do its job properly if rotated; I thought the whole point was that the oval needs to be in sync with your pedal stroke? Or am I being thick here?
I think it probably because the idler pulley changes what area of the chainring the chain is interacting with. Instead of the chain coming across near-horizontal, it's coming down vertically - changing the "phase" of the oval ring it's interacting with. It would end up being almost opposite to the normal oval "benefits" as the timing is probably 80-degrees out.
 

Tubbsy

will do custom titles for cash
Staff member
Yeah ok that makes some sense @beeb - although I'm guessing you'd need a chainring that can be mounted in a bunch of different orientations to get it just so, and even if Shimano's four bolts were in a square pattern it might not be enough?
 

beeb

beebenson
I don't know tbh, I don't run oval rings so have also never played with different timing. The design of the bike (ie: idler pulley location/chain angles) would also have an impact, so I doubt there's a one size fits all solution regardless.

But yes, if there's some kind of chainring attaching 'standard' that allows different clocking at fairly small intervals that'd be what you want.
 

ozzybmx

Níl aon tóin tinn mar do thóin tinn féin
I have run quite a few ovals and the 'timing' is the part that makes the oval ring work, it suppresses the pedal stroke at the point where your feet are at 12 and 6 and then ramps up as you go through the power part of the stroke, easing off again as the foot that was at 12, reaches 6 at 180° later, so ramps up and eases off twice every 360° revolution.

There would only be a few degrees of flexibility before it would be detrimental running an oval.
 

shiny

Go-go-gadget-wrist-thingy
Right you are, my memory failed me completely..

I thought they were against it in this interview with a bunch of high-pivot manufacturers:


It's a good little article for anyone interested in these types of bikes.


However I don't really understand how an oval ring will do its job properly if rotated; I thought the whole point was that the oval needs to be in sync with your pedal stroke? Or am I being thick here? Maybe a direct mount ring can be adjusted in small increments, I've never used one though.
Thanks for the link, not seen that one, will have a read tonight.

I think it probably because the idler pulley changes what area of the chainring the chain is interacting with. Instead of the chain coming across near-horizontal, it's coming down vertically - changing the "phase" of the oval ring it's interacting with. It would end up being almost opposite to the normal oval "benefits" as the timing is probably 80-degrees out.
Bio-Pace? As @ozzybmx said it’s such a small window for getting it right that on a high pivot it may not be worth it. I have tried oval and honestly felt little difference to a round ring. Maybe the downstroke was a bit faster but was not the huge difference I was excepting.
 
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