Chris Froome is using these weird chainrings, and they might be helping him win a historic 3rd Tour de France

Tour de France leader Chris Froome and his Sky team are among the most tech-savvy people in pro cycling. An example is Froome's use of non-round chainrings.

Froome's rings are not branded - probably to avoid conflict with his team's sponsorship by Shimano, which supplies Team Sky with components and wheels - but they are made and patented by Osymetric. French mechanical engineer Jean-Louis Talo invented them.

Osymetric USA claims the chainrings "let you achieve 7-10% more power" and that the "patented bi-cam design allows you to take advantage of the strongest part of your pedal stroke, giving you 7-10% more wattage without doing any more work." Froome has been riding these rings for a few years, so he must believe they give him an edge.

And while there are other riders in the peloton who use non-round rings too, none of Froome's big rivals are on them as far as we know. And yes, these rings are UCI-legal, UCI being the French abbreviation for the International Cycling Union, world cycling's governing body.

Here's a closer look at the unconventional chainrings that the Tour de France leader is using: