68venable

I appreciate the resurrection of these threads. My cannondale has biopace and I've been trying to read about it. I've had it for 4 years or so I guess and had it out on loan for about 3 of the 4. The dozen or so times I rode it, I couldnt even tell a difference. It took a guy out on a ride to tell me about it a week ago. How embarrasing not to know that about a bike you are riding lol. I've never felt a difference and that late 80's Cannondale Crit Series feels considerably faster than my 2009(i forget the actual year) Specialized Allez.

Trakhak

Oval rings oriented to achieve the highest pedaling load at the horizontal crank position per the Rotor and Q ring designs have been around since at least the 1930s and probably before that. That fad does indeed come and go.

Shimano's engineers analyzed the running stride as it pertains to cycling and recognized that the human leg has evolved to deliver maximum force most efficiently with a less acute knee angle, i.e., with the leg closer to full extension, than that seen with circular rings, let alone Rotor or Q rings. In addition, they recognized that the proportion of time spent delivering power is lower per running stride than per pedal revolution with circular rings (let alone Rotor, or Q rings).

Biopace rings are designed to mimic the mechanics of running by increasing the effective gear ratio at the point in the pedal stroke that corresponds to the running foot strike and also increasing the rest period per stroke. The compromise is that the design works best at up to the average running pace of 90 to 95 strides per minute and less well at higher cadences.

Biopace was reviewed in the various bike magazines at the time of its introduction as a brilliant advance in the ergonomics of cycling. Then, after 6 months or so, the reviewers started hearing complaints from racers about the uneven pedal stroke interfering with high-cadence attacks and sprints.

Since the only thing that sells more magazines than "It rules!" is "It sucks!," the benefits of Biopace for the majority of riders for most riding were thereafter ignored, and the design was vilified. The benefits are subtle, and subtle doesn't sell.

The Rotor/Q ring design appeals to common sense; the advantages of the Biopace design are nonintuitive. Common sense isn't always reliable; that's why science was invented. Turn your Biopace rings to any orientation you like, but give the Shimano engineers credit for knowing what they were doing.

jimmuller 

Well, I've never eaten many food that I just know I won't like. With that in mind I'll confess that I've never used either Biopace or Rotor/Q. And that won't stop me from making the statement:
Biopace always struck me as a solution looking for a problem, the answer to a question that was never asked in the first place.

ThermionicScott 

Hence my consternation at these threads -- however the rings are oriented, they seem like a way to compensate for uneven pedalling technique. Biopace made the gear "big" during the dead spot to carry more momentum through it. Rotor/Q makes the gear "small" during the dead spot because you're not applying power then. Neither approach is necessary if you shift to the right gear and pedal it smoothly.

timtak

I agree with what you are saying.

There is an inherent problem in cycling in that humans are up-down-motile bipedalists, whereas bicycles require us to be circular motion cyclists. Biopace unrotated attempted to force bipedalists to become bicyclists. Take for example the comment
Whereas Osymetric and Q-Rings force the bicyle to have, as it were, pistons to conform more to the bipedal rider.

So a suggestion: use the Biopace (or round rings) in their old, unrotated form for training, to force yourselve to spin, and then rotate them -- to become Osymetric, Rotarized, Q-Ringal -- on race days to give yourself a bipedal boost.

This may be a bit like altitude training.

I will start gently. I have bid 20USD on a pair of Biopace HP. I think I will only use them Rotarized.

timtak

I agree with your overall sentiment of praising the Shimano engineers, but I don't think I can agree with all of what you are saying here On the contrary, if you look at the human gait

You will see that we deliver maximum force with a more acute (more bent) angle mid-stance, and that is why there is a "dead spot" in the pedalling cycle, because we are bipedal. natural-born-runners, and do not naturally deliver force with our knees fully extendend or bent at right angles.

If you think about it, it is pretty much impossible for the leg to deliver power when it is fully extended, because it can't extend any more. It can only push backwards, which is what we are encouraged to do when pedalling, and scrape the mud off our feet. But that is not where there main power of running or pedallying comes from, it comes when the knee is semi bent in mid stroke/gait when the leg is extending.

The Shimano engineers realised this, and realised it was a problem - we don't pedal in circles. So they designed a pedal to force cyclists to adapt to the needs of the circular motion bicycle.

From this blog post on the use of Rotor Q-Rings. This is a round chainwheel power output plot over the pedal cycle

As you can see the power output is not an ideal circle - even power output over the whole pedal cycle. Biopace corrected this (and caused knee pain).

This is the plot using Rotor Q-Rings.

As you can see it is worse, in that it is even less circular. It is allowing and encouraging the rider to mash. But bipedal humans are mashers, so it is letting and encouraging us to do what we were made to do, and it will be easier on the knees than attempting to push the pedal over the top of the circle or "scrape the mud of your shoes" and apply torque at the bottom, but at the same time it should worsen pedalling style.

Perhaps that is why Wiggo gave up on them after a couple of seasons. He should use Biopace in the off season! Perhaps I will try that, and Rotorize in the spring.　

I won the auction and have bought two new Biopace chainrings 52T/42T for 19USD :-)