Juan Foote

I did a quick search that didn't turn up what I was looking for, specifically. If there is already a thread on this discussion, I would appreciate someone linking me to it.

The LBS is on a test program for the Qrings. They are doing a intro price to "rent" the rings, and the customer is asked to test them for 300 miles. After this you either give them back, or the purchase price is reduced by the up front fee. Lots of the club guys are being sold on it and are convinced it works.

My immediate thought was, oh look, it's Biopace again. I was shown that it most definately is not Biopace. One of the most significant differences you can tell right away is that it doesn't change the chainline length. The RD does not move while you pedal. This brings up an immediate question as to the actual effect of the rings themselves, and would like to have y'all explain to me how I am wrong (or not).

In my thought about it, I considered that if the chainline isn't changing, as reflected by the lack of RD movement. If the chainline isn't moving, then isn't the gear ratio really just staying the same? In other words, they have this nifty looking oval ring, but it is still taking up the same amount of chain length, regardless of what part of the ring you are on.

I can recall from owning Biopace years ago that you could feel a surge in the pedal stroke. You could actually feel the back tire go faster, then slower, as you went around the crank stroke. When I test rode the Q ring bike I could not feel that surge. It was smooth all the way around.

Considering that with a chainwheel, you are being effected by the entire length of the cog and its interface with the chain, not just one part or side of it (like a wheel where the contact surface is only the bottom) I really don't feel like these rings are doing anything aside from placebo effect which is quite powerful on it's own.
I invite you to prove me wrong, or explain it in such a way as to make me understand WHY it's working the way they say, without changing the chainline.

simonaway427

1) Look closer, you RD DOES move - its more pronounced when you're on a smallest cog (11T)

2) Q Ring and Biopace are 90 degrees out of phase. The biopace design had it EASIER to pedal during your downstroke, with the "long end" of the oval coincident with the dead spots in your pedal stroke. Q ring is the opposite. The long end of the oval is coincident with your down stroke, so you're making more power when it matters most, and making it easier to pedal during the dead spots.

BlazingPedals

Q-Rings seem to be more popular with 'bent riders. The advantage of them is that you can adjust where the high and low spots are in the pedal circle. So you can either install them to 'fall' through the dead spots or the power part of the stroke. That's why 'bent riders like them: the relationship between the legs and chain line varies between different styles, and they need the adjustability. Just to clarify: yes, the RD does move. The downside, aside from cost, is that the front doesn't always shift quite as well since the distance between the ring and the FD cage varies throughout the pedal stroke.

plpete

As it was said, the RD does move but it is very subtle. You won't see it swinging back and forth. I never rode the biopace rings but the main advantage for me with the q rings was the smoothness of the pedal stroke, especially while climbing. Now when climbing my pedal stroke seems a lot smoother as the dead spot has been greatly reduced or even eliminated. Also I found myself riding 1-2 cogs smaller since I was not wasting power in the dead spot. If you really want to feel the difference between round and the q rings ride with the large q ring and a small round ring. This is how I tested it. Your legs will tell a difference in the way you pedal as soon as you shift. First few pedal strokes fell "odd" and then your legs adjust. Shifting can be set up to work just as well as with round rings. All I had to do was slightly raise my FD but the majority of adjustments is done by properly angling the FD. It shifts perfectly with my SRAM Force FD. Many had luck with Shimano FD as well. Its just a bit of a PITA to get the adjustment right. In the end I was sold and purchased the small ring and plan to use them for good. After wheels this was the best upgrade for me.

ruindd

I had a set and I agree with everything said here.

1) The chain length does change and you can see your RD taking up the slack.

2) Rotor Rings and BioPace are technically as different as is posibble. They're 90 degrees out of phase with each other.

3) Rotor Rings shift fine if you set up your FD correctly. See this thread/video for details.

https://www.bikeforums.net/showthread...gs)?p=11464684

LesterOfPuppets

I like to advance my Biopace rings by one hole. Lots of folks did that back in the day. Biopace only gives you 5 different ring orientations, while Rotors give you, umm lots more.

I don't mind Biopace on larger rings but it was kinda kooky on MTB cranks, I'd always swap out my little ring for rounds.

Sheldon Brown claimed to have run Biopace fixed gear, so they don't take up differing amounts of chain at different points in the stroke.