Odd shaped front sprocket on Tour de France.
Discussion
As mentioned before, this is not a new idea. I had Shimano BioPace chainrings on a Raleigh Record Sprint in the mid 1980's. Supposed to even out the pedalling action by bringing your foot round to apply power more quickly than a circular chainring, or something like that. The Record Sprint was second hand, and a birthday present, so I had no hand in choosing it.
AyBee said:
Designed to help the flat spot when one pedal is at 12 o'clock and the other at 6 IIRC. Interestingly I don't think Wiggo was using it on his road bike, just the TT machine?
A comment from Phill Legget during the tour was that whilst you say is true, it was debatable whether it made any difference.Did I notice on his bike today or not?
My understanding is the new ones work in the opposite way to Biopace.
Biopace tried to make the power transmitted to the wheels even, by increasing the effective gear at the dead spots, which wasn't very effective as they are dead spots because it's virtually impossible to put much power through the cranks at those points.
The new ones increase effective power by acknowledging the deadspot, putting a smaller gear there so you can at least put down some power, and maximising the gear at the power positions when your legs are able to deal with it without fatigue.
Didn't one of the big players (Schleck?) have an issue on a mountain stage last year by changing front ring at the point where there was a tiny ring, throwing the chain off? Imagine that is something that could be prevented through good programming of Di2...
Biopace tried to make the power transmitted to the wheels even, by increasing the effective gear at the dead spots, which wasn't very effective as they are dead spots because it's virtually impossible to put much power through the cranks at those points.
The new ones increase effective power by acknowledging the deadspot, putting a smaller gear there so you can at least put down some power, and maximising the gear at the power positions when your legs are able to deal with it without fatigue.
Didn't one of the big players (Schleck?) have an issue on a mountain stage last year by changing front ring at the point where there was a tiny ring, throwing the chain off? Imagine that is something that could be prevented through good programming of Di2...
Catchme said:
What surprised me was how much chain movement there was when using the oval rings. I'd be concerned about shipping a chain timetrialling on our roads.
I thought that too, and wondered if the energy lost with the flapping chain would make using a tensioner a viable option.Greg66 said:
AyBee said:
Designed to help the flat spot when one pedal is at 12 o'clock and the other at 6 IIRC. Interestingly I don't think Wiggo was using it on his road bike, just the TT machine?
He uses osymetric rings (as does Froome) all the time. The other non-circular player is Rotor.
AyBee said:
Was he using them in the tour? I only really noticed it on the TT bike.
Pretty sure I spotted them on the mountain stages. On the flat stages he's rarely isolated enough for the camera bike to get close enough to see. This article http://www.bikeradar.com/gallery/article/race-tech... also suggests that they are in use full time.
I use Rotor Q Rings rather than Osymmetrics. I like 'em.
prand said:
Catchme said:
What surprised me was how much chain movement there was when using the oval rings. I'd be concerned about shipping a chain timetrialling on our roads.
I thought that too, and wondered if the energy lost with the flapping chain would make using a tensioner a viable option.What energy lost by any chain flapping (didn't look at all bad to me) would be countered by the benefits of the chainrings: Sky would've looked into that for sure!
Jimbo. said:
IIRC Wiggins did experience a chain dropping due to oddball chainrings a few years back (in his Slipstream/Garmin days), although I can't remember what event: it was a TT of some sort, that's all I recall!
What energy lost by any chain flapping (didn't look at all bad to me) would be countered by the benefits of the chainrings: Sky would've looked into that for sure!
You might say that but I tweeted Seat Yates and am waiting for my call! ;-)What energy lost by any chain flapping (didn't look at all bad to me) would be countered by the benefits of the chainrings: Sky would've looked into that for sure!
robpearson said:
I think cycling weekly went into this a while ago. The theory was that the alleged performance gain of the oval ring was greater than the time lost by the chain coming off. I would have thought the frustration would do as much damage as the lost time personally.
They shouldn't come off. They are quite a bit harder to index properly, but once done properly, they shouldn't drop. I know this to be true, because I index mine, and they don't drop. Gassing Station | Pedal Powered | Top of Page | What's New | My Stuff