non-round chainrings?

[M-Power]

And FWIW, i tried biopace when they were originally out, swapped to some round rings pretty sharpish, the way the pedal seemed to fall away was disconcerting to say the least!

+1 never liked em. Dont worry, the industry will bring out square rings next year, followed by the 'lighter' triangular rings the year after....then they will say they have invented something revolutionary.....the round ring, the year after that :facepalm:

 

[hamster]

And L-shaped cranks to help you over top dead centre...

 

[mattr]

Well, pay someone enough and they'll use any old rubbish. ;o)

 

[jimo746]

Well, pay someone enough and they'll use any old rubbish. ;o)

I already am!!!

 

[Woz]

The idea is that they give a reduced diameter over the top dead centre so that you get a reduced load when you can apply least force. Biopace actually did the opposite, the idea was that it created an action more like running and that at TDC there was a significant backwards force from the lower pedal (think pushing with your foot).

Speaking personally, I hated the noticeable pulsing torque and joyfully confined the rings to the bin in 1991. If they work for you, great.

Had them BITD and fiddled with turning just the granny clockwise I think to increase the power on the down stoke.

The choppy ride sensation kicks in at higher RPM. No magic number but I'm somewhat of a masher so was perhaps more sensitive.

The choppy sensation was worst when running out of gears on a long fast descent and effectively
spinning. Literaly saddle bob.

I also got the impression there was
more chain slap and chain suck.

Eitherway, when the rings were 50% worn they were binned.

 

[street]

I have no experience with the latest incarnation but I have to say I do like Bio-Pace. Perhaps it was a placebo effect but I felt like I could slog up steep hills better with them. It does mess with your rhythm for juat about anything else though as has been pointed out.
I had a nice round 50T and biopace 38T and 28T and that was perfect for me.

 

[julesg007]

I too remember Biopace rings from BITD and had some myself.

Being honest it was so long ago I can't even remember if they were any good but what I do remember was they weren't very long lived and supposedly caused knee problems and it was actually better to move them round slightly to get them to work better.

Seeing non round rings being used nowadays did have me wondering what had changed and if the pros were using them they must work but hey I'm no expert but did find the following video of You Tub which was interesting; https://www.youtube.com/watch?v=TCUWtj7lc8I

 

[mattr]

Just coming back to this as i realised that since my last post "trying out oval rings" i've bought 4 more of them (for best/race bikes) and changed crank length (tested in all combinations, long/short/round/oval).

On balance, it's better enough that any more replacement rings i need will be swapped to oval as i get round to it/wear them out, as a rough guide it seems to give you an few gear inches when climbing, so rather than struggling on a round 38, the oval 38 *feels like* you've got a 36 fitted. But you are still travelling at the same speed. If that makes sense.

On a lot of the riding i do, it's the difference between dropping down a chainring, or not.
Also seem to be slightly less fatigued, but that could be in my head.

 

[Woz]

Here's something to try old school DH with....

https://www.ebay.fr/itm/REYDEL-COURONNE ... SwU9xUN4dj

The chain guard would need to be half way up the seat-tube though.

 

[RadNomad]

Re:

If science can’t prove anything on this topic by now, it’s a gimmik surely?