Froome's chainrings from the TdF

[Keith A]

Just saw this picture of Froome's chainrings -- they look pretty extreme. Has anyone tried something like this?

[Bruce K]

I forget what brand they are but he and Sky have been using them for years

The benefits are still being debated by a lot of folks but I would think they have done data that it is, at least not a detriment.

BK

[Black Dog]

They are designed to make Froome a graceful bike rider. Mission accomplished

[bikinchris]

Various non round "Bio" and other named rings have been tried since the 70's at least. They all failed. Many people thought they made the pedaling feel wrong. The idea was reducing the stress on the dead points of the pedaling motion. Yeah.

Most riders spend a crazy amount of time trying to learn to pedal as round as possible. Riding with Souplesse is the goal. "Supple" round perfect pedaling is actually unobtainable, but the better you are at it, the more energy you save. People who use out of round chainrings have no hope of being smooth.

[sales guy]

Originally Posted by Bruce K

I forget what brand they are but he and Sky have been using them for years

BK

He uses the Ossymetric brand ones. Rotor has some oval rings as well in the Tour.

[dgauthier]

Originally Posted by bikinchris

(...) They all failed. (...)

Yes, didn't Shimano have a variation of this called "Biopace"? Froome's chainrings are yet another variation on the oval-shaped theme in that these look like they have sllightly flatter spots at intervals around the circumference (unless the picture is somehow distorted).

I am frankly surprised to see these in this day and age. I wonder if the team has any data indicating a benefit. Or perhaps, the placebo effect itself produces a benefit...

[Matthew]

Every four revolutions they automatically pull his head down toward his stem.

[ofcounsel]

I'm using Absolute Black oval chainrings on my mountain bike. They feel a bit odd pedaling at first on flat ground, but they feel like I have a little bit more traction and pedal natural while climbing.

[yashcha]

I just started back on the rotor q chainrings. The last time I used them was back in 2011-2013, but I gave up on them because I hated how bad the shifting was, compared to the stock rings. A month ago I picked up a set here, 52-36, at a great price. The new generation of Q-rings seem to shift much better than the 2011-2012 version. Although shifting is noticeably worse than the stock 6800 rings, I find that it is still acceptable.

I use the epic KOM on Zwift as my fitness test route. On the stock rings, I typically average about 190 watts at 180 BPM (measured on a Stages) for about 27 minutes. At 62 Kg, this is my weekly sub FTP sweetspot workout. On the Q rings, I average the same watts, but my HR is around 170. This week, I will test how many watts I can push at 180 BPM.

For my riding style, Rotor seems to give a slight advantage, for that range of effort, which I have tested. Yes, very rudimentary testing and results so far, I hope to post more observations as I get more data points at different effort levels.

[jumphigher]

I'd try them, I think there is something to their claims. I've used Biopace rings many times and have always thought they worked well. And I cant believe Froome would ride something that he thought was BS..

[GonaSovereign]

Those are Osymetric rings, from France. Shimano would much rather Froome was on Shimano rings, so the Osymatrics must work for him.

[torquer]

Originally Posted by jumphigher

I'd try them, I think there is something to their claims. I've used Biopace rings many times and have always thought they worked well. And I cant believe Froome would ride something that he thought was BS..

The long axes of the ovals for Biopace and contemporary non-round chainrings are oriented 90 degrees apart.
https://en.wikipedia.org/wiki/Biopace
According to that company's Wiki page, Osymetric rings are "tailored to the pedal stroke of the individual cyclist." If they truly are customized, that could account for overcoming some inherent weakness in the rider's physiology.
It would be interesting to see what testing is performed by way of "fitting" their rings to a particular customer.
Or, it could just be marketing hot air...

[Ti Designs]

Originally Posted by bikinchris

Most riders spend a crazy amount of time trying to learn to pedal as round as possible.

Kinda like teaching a pig to sing...

Look a the human body on the bike, one muscle moves one joint in one direction, that can be applied to the pedal at a specific range. Example: The glutes extend the leg from the hip, so they can drive the pedal from 1:00 to 4:00 (the hip is behind the bottom bracket). The amount of force you can generate at the pedal depends on the size of the muscle and the mechanical advantage of the attachment points. The bio-mechanical efficiency of any muscle is related to where it is within it's range of motion.

Given that, you have the largest muscle group in your body, the glutes, pushing down. You then switch to the hamstrings - the longest muscle group in the body, pulling back. The amount of force you can generate is low, but the chance of cramping or injury is high. Then it's the hip flexors pulling up, to their end range of motion where efficiency is near zero. Then it's time to push forward with the quads...

You have two large muscle groups which push forward and down, and almost no ability to complete the pedal stroke on that side. The only way to pedal "round" is by limiting the use of the large muscle groups (which is really stupid) Forget about pedaling "round", learn how to use large muscle groups where they're effective. That's the whole game.

[ultraman6970]

I used the shimano bio pace for racing and they sucked, the problem with those in specific is that you cant spin at all, once you are to a pace will keep it but if you need to accelerate you wont be able to do it comfortably as with rounded chainrings, after like a week I took them off.

Probably in a TT with a 54 chainring would had been nice but regular racing they sucked, everybody I know that used them had the same problem, for a lady that goes to the store the biopace was great, slow and steady pace.

I believe the rotor chainrings differ from biopace because you can swap the position of the curve to fits you better. I heard the reason Froomey fits weird over the bike is to accomodate those chainrings.

[gianni]

Originally Posted by Matthew

Every four revolutions they automatically pull his head down toward his stem.

+1

It was driving me crazy the other day, like every 4 seconds. I'm amazed he doesn't overlap wheels more often.

Bring on the hate but it's hard to watch.