Thursday, March 06, 2008

12 Active Spokes : Dynamically Weighted Wheels (DWW)

Russel Kalil of Tarryan Technologies, an engineer who also happens to be an Ironman, dreamed up an idea that could make the best folks in the bicycle wheel business look dum.

How about a wheel that could increase and decrease its moment of inertia according to your riding speed? As a cyclist rides up hill, weight transfers closer to the hub and while he descends with the added speed, the weights move out to the rim for the extra momentum.

The concept is simple. You don't need a new wheel nor have to rewire your brain like pedaling on Power Cranks. Active Spokes uses small sets of weights (each weighing 0.5 oz) in 3 sections that fit onto the spokes of the non-drive side of your existing rear wheel. The choice of these sections depend on the average speed of the rider. The applications for which this is more suited for are rolling type hill road races and triathlons.

With speed, the centrifugal force in the wheel moves the spring loaded weights far out towards the rim. The motion of the pieces can be manipulated with a choice of springs that have different constants. More on this technology and sample calibrations can be found on the Active Spokes website.

Russ employed the help of Dr. Voelkel of RIT and a test rider to do a study in a hilly part of Skaneateles NY. The claims are that wheels fitted with active spokes outperform a similar wheel without the technology. Interestingly, famous cycling coach Joe Friel and his son Dirk have both endorsed the invention so that makes me some 10% more interested.

Left to right : John Cobb (BlackWell Research), Russ Kalil and Coach Joe Friel at the Serotta International Cycling Institute Conference (Jan '08)

But the questions are :

1. Won't the addition of more weight effectively counteract any difference in inertias achieved?
2. Does this work reliably under various conditions?
3. Will it make rattling noises when the wheel is in motion?
4. Will the pieces dent the rim?
5. Are the pieces and springs stainless steel? They are exposed to the elements.
6. What happens if the spokes break while riding up a hill (extreme) and you lose all your active spoke pieces down the road?
7. How about if I prefer my favorite wheel magnet on the non-drive side?
8. Wont they stir up some aero drag?
9. Will the UCI approve of it?
10. I have more area to clean now :(

Moment of inertia trouble a few cyclists daily but they only play a role mainly in acceleration. Some will argue that accelerations are not much in a bike race, but surging or attacking on straight roads are not the only scenario. Even while cornering your bike, you are technically accelerating since velocity changes with time.

Myriad questions aside, spending less than 200 dollars on Active Spokes while sacrificing some cleanliness as opposed to completely 'un-weighing' your wallet on a pair of Lews or Lightwheels may be an attracting factor for some.


  1. Ron,

    Kind of looks like something called a 'clutch', don't you think?


  2. Blue,

    If you're thinking lawnmover clutches, yes they operate on the same centrifugal principal.

    In a way, you can think of the dynamic weights in the wheels as operating some sort of "mini gear" in addition to the chain drive system you already have. As RPM increases, spokes move out due to rotational motion and you have some more oomph to get the wheels rolling since the weights are now near the rims. How much they help I don't know but some more tests will tell.

    Nice idea though.

  3. Great article,

    I must say this is a fascinating idea. And yes, I need all the help I can get.

    But - if it works too well - where is the line between man powered and motored?

  4. I can see how this could be true. If you take a figure skater spinning in circles; when she has her arms spread out she's going slow, but when she brings them closer to her body she goes a lot faster. I'm guessing this is following the same concept, but I agree with many of your questions you have Ron, like with cleaning it, what happens if one breaks, aero-drag, etc.

    It really is an interesting concept, and I would be interested in buying a set once USACycling, UCI, etc. all approve of it. As far as I know nothing has been said of it.

  5. Great post, Ron. I have yet to see anyone highlight these wheels.

    I don't see the UCI approving of this as it can almost be viewed as an "energy storage device" - which are already outlawed. (The spring system is "storing" energy as the weights move outward. That kinetic energy is released as the rider slows and the weights move toward the hub and change the distribution of weight on the wheel...)

    As for the Joe and Dirk Friel endorsement...Joe is also listed as an officer of the company on their own website. Hardly an unbiased endorsement. I think Trek and Parlee make the best carbon bikes - but I'm also biased because I happen to sell the too. :)

  6. Russell Kalil1:00 PM

    Hi Ron,
    Thank you for your kind words....and valuable questions.
    We have a 'Visitor's Questions' section on our site. If it's ok with you, I'd like to post your questions and address each individually. Our site will update later tonight and I'll provide the link to this forum.. If you like, I'd be happy to reference your site...
    Let me know what you're comfortable with...and again, thank you.

    Russ Kalil
    Active Spoke

  7. Will - That is an interesting question. Bike racing 'pundits' believe that a rider putting the most 'power' in need not always win. Racing is now a cunning game of energy conservation and 'going' at the right moment. Technology has brilliantly bridged the gap, allowing racers to use their matches only when they need them. But the UCI decides what is fair game.

    Zach - Are you a figure skater or a cyclist :) Jk..

    Matt - All good points there.

    Russ - Pleasure to have you comment here. Feel free to quote me and ridicule me as much as you like :) But no, I think it'll be a good connection. Sure, post a link. Readers here can then visit your forum.

  8. Russell Kalil4:09 PM

    Hi Ron,
    I've posted the responses to your questions in our Visitor's page.

    Thanks again for the opportunity to contribute.

    - Russ

  9. Thanks Russ. I like the way you addressed the questions specifically. I'm sure many others would have had similar ones.

    This will be very helpful. Good luck in your design!

  10. I really like the concept, it makes sense. Any plans to produce something like this?

  11. Ron, I used to like watching figure skating, and a friend of mine is a figure skater... that's why I thought of it haha.

  12. Anonymous5:25 AM

    This is not a new invention.The concept was originally based on the use of water in capsules that moved towards the rim at higher speeds, and back towards the hub as the wheel slowed. Unless kalil studied engineering after moving to the US in the 80's, he is still only qualified as an electronics technician, and l dont believe he has ever invented anything. 'His' inventions all come from other peoples ideas.


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