Q&A: Are non-round chainrings beneficial?

Readers - Maybe because pedaling takes effort, inventors have been attempting to improve the bicycle drivetrain almost since Pierre Lallement first created it by attaching pedals to the front wheel of a dandy horse around 1862. So I thought this question about non-round chainrings was a good one to share.

If you have an opinion, your feedback is appreciated.

Click to read Road Bike Action's review of Rotor Rings

Q: Would you please consider addressing the possible benefits of Rotor Rings or point me to an article that does?

Appreciate all your helpful articles,
Valerie

A: Thanks for the interesting question Valerie.
Rotor Rings are challenging for me to comment on. To some they are revolutionary products that improve your power and efficiency. To others they are snake-oil, i.e. nothing but hype.

What's really needed is a truly scientific analysis and even that would be highly challenging since the argument can be made that if you learned to pedal on a standard chainring you need to "learn" how to pedal the Rotor Rings before you can analyze their benefit - or put a number on it.

Having tried various non-round chainrings, oval chainrings, Shimano Biopace rings, and cranksets with cams designed to avoid the loss of power in the dead spots in the pedal stroke, like the Houdaille Powercam, (which I actually rode thousands of hard miles on and wrote a positive review on back around 1986), I have never found any true, long-term benefit from these "advanced" chainrings/cranksets. So I don't believe they do anything except change how you pedal slightly.

Sharp's book is readable on Google books (pg. 428 shown)

Alternatively shaped chainrings have always been controversial like this. Archibald Sharp wrote about them in his analysis of bicycle and tricycles in 1886 (clipping right). 

Now I know full well that some top riders have ridden and done well on the Rotor Rings - like former pro roadie Bobby Julich for example. However, I do not believe Bobby would have done any worse on standard chainrings and I didn't see him suddenly winning more on the Rotor Rings.

I know that for some special events, such as time-trial racing, the Rotor Rings can allow some riders to pedal more comfortably in the aero position because of the extreme position. Shorter crankarms will do the same thing (a lot more on crankarm length in a future blog post). But that is one application where a non-round ring might help some riders.

Ultimately, the only way to know if you'd like them or not would be to try them. But, you would want to carefully compare them to what you have now because at first blush they are going to feel different and different sometimes feels better just because it's different. What you want to determine before spending the money, and it's a lot of money - is if they actually improve your efficiency in some way.

One way to do this would be to have a fitting specialist in a bike shop (or you could do this at home), look at you pedaling on a trainer with regular rings and then the Rotor Rings. Videotaping would provide a direct comparison. You could watch to see if you pedal more smoothly with the Rotor Rings. If so, that's an indication that you might save energy on them and feel more comfortable on rides.

The first thing to think about is if you have any issues with your pedaling right now. If you do (maybe you rock around a lot on your seat when you're pedaling - an indication that something's not right), maybe the Rotor Rings would help you smooth out. However, issues like this can be caused by other things too, like a seat in the wrong position, so you'll want to rule out those things too - before trying the Rotor Rings.

If you end up getting the Rotors, I'd be interested in hearing what you think. Maybe you can find a bike shop that sells a lot of them that has a loaner bike they let people take real rides on. That way you would be able to ride a loop you know on the rings, which is a good way to get an idea how they work for you. If you bring your regular bike, you can do a back-to-back comparison, too. If you check Rotor's dealer locator maybe you can find such a shop.

Good rides!
Jim