E-Hub

Road 19 70

I am still catching up from my vacation last week. It really was great to get away for a few days, play in the ocean with my kids, and totally relax, but I did come back to a LOT of email. I am catching up at work as well, so it might take a while for me to answer all the email I received pertaining to the blog.

Tonight though, I want to quickly point out a product that caught my attention today in the September issue of VeloVision magazine. On page 32 they reviewed the E-hub, a rear hub that was designed in Slovenia to even out a rider’s pedal stroke. The E-hub is certainly not the first component that promises to smooth the pedal stroke to order to increase performance, but they are taking a different approach. As the website explains:

“Human muscles are developed for walking and not for circular pedaling. As a result, cyclists experience a “dead spot” of about ±15 degrees around the top and bottom of the pedal path. Several products such as ovoid chain rings that were marketed in the 90s tried to address this problem with poor success or bad side-effects. E-HUB solves this problem once and for all with a unique patented spring mechanism in the hub that overcomes the dead spots while allowing the cyclist to keep her/his usual rhythm.”

While you are at the website, watch the video with pro and elite level riders talking about how the internal spring improves pedaling efficiency resulting in an overall speed increase. I admit to being intrigued by this design, but also a bit skeptical. The VeloVision reviewer did say the effect was noticeable, especially on steep uphills, but in the end he said, “There could be an actual biomechanical improvement, but I’m not 100% convinced it was significant.” That makes me even more skeptical, but I would still love to try the hub for myself.

Regardless of how well it works, I was initially intrigued by the fact that this hub, which basically redistributes pedaling energy to boost performance, is being marketed for racing. They even point out that it is approved by the UCI, which I have a have a hard time believing will remain the case if it really does offer time gains up to 10% as the website claims. So what do you think of a hub that uses an internal coil spring to even out the pedal stroke and better distribute a rider’s pedaling power to the rear wheel? If there is a true biomechanical advantage as claimed, should it be allowed for racing? I have my own opinion, but I am curious what you all think.

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19 Comments

  1. slowdad October 21, 2009 at 8:35 pm -  Reply

    I don't get how there could be an advantage in this type of system from a theoretical standpoint. Mind you, it's been a while since I got done my mechanical engineering degree.

    Isn't this just an energy storage system? And all energy storage systems are less than 100% efficient.

    If you even out the amount of power applied to the wheels, you're still applying the same amount of power through one complete pedal stroke, so maybe the peaks are lower and the valleys higher, in the power graph, but overall it's a wash.

    The other methods discussed tried to make the legs more effective at applying power therefore allowing more total power to be applied over time.

    Now, if it did work I don't think that it should be allowed only for the can of worms that it opens. What about a hub that, instead of storing and releasing energy during a pedal stroke, slowly stored energy over time, which could then be released by pushing a button? Then you could beat Cavendish!

  2. clever-title October 21, 2009 at 8:42 pm -  Reply

    I'm with slowdad. In essence, it's storing some of your energy from the power part of the stroke in the spring, and returning it in the dead part.

    If it's a simple spring system, it should return 100% of the energy put into it, but because it has to move, I figure there is some loss.

    I think it'll be like suspension forks – in some instances, it'll be helpful, but the energy losses and added complexity will make it a novelty.

    Disclaimer: I like my ancient biopace chainrings.

  3. Zhefei October 21, 2009 at 8:57 pm -  Reply

    I agree with the points made, that it is just an energy storage system, and that it will be less than 100% efficient. Because it's just a spring, it should be pretty close.

    However, this does lessen the peak force on each stroke, and brings the applied torque over the stroke closer to the average. This, in essence, is creating a more efficient pedal stroke, is it not? I find when I smooth out my pedaling I am less fatigued.

    It is also consistent with the claim that it helps on uphills. I find that I resort to mashing the downstroke, and this would carry some of that energy past the dead spot.

    Now that I've thought about it, it would certainly be interesting to test ride, and play with the different spring rates. I bet you could get some funny oscillations at certain cadences.

    Allowed for racing? I don't see why not. Besides a long history of banning cycling innvations.

  4. adamrice October 21, 2009 at 9:19 pm -  Reply

    The fact that the UCI is allowing it suggests that it can't confer an advantage.

    I'm not engineer, but I also can't see how it would work. Perhaps if it somehow allowed you to push harder on the downstroke than you could otherwise, and released that excess in the dead zone. But I'm already pushing as hard as I can.

  5. Anonymous October 21, 2009 at 10:32 pm -  Reply

    You're all just speculating. Let me give you some real-world experience. A friend of mine built a system that did the same thing with a spring arm on the tension side of the chain. We rode it up a steep hill near my (then) home in Seattle. The difference was significantly noticeable on the steep low-speed climb. My friend commuted on the bike for a while and also found several percent reduction in travel times (consistently since this was a route he rode regularly). What you're overlooking is that leg muscles work best in a "burst" mode – releasing their energy quickly, then storing it up for the next burst. There is little mechanical efficiency loss in a spring because of its makeup. However, there is a substantial increase in physiological efficiency by applying leg power in burst. My friend made several subsequent efforts to mechanize this system into the crank but eventually moved on to other things.
    I don't think much of the idea of putting the spring in the hub because of the added rotational inertia but I concede that this makes it easy to adapt to existing bike designs. I'd like to try one on my lowracer recumbent, cause that thing is already fast. I now commute 30 miles and a little more speed and lower effort is always welcome.
    Nick Hein
    Morgantown, WV

  6. B. Nicholson October 21, 2009 at 11:22 pm -  Reply

    If you could control it with a freewheel switch of some kind, you might get mechanical regenerative braking I suppose. That could be worthwhile, too, particularly in heavy traffic with many stops. Some cushioning from the spring might also be nice. Is it worth the added complexity? Maybe.

  7. GeekGuyAndy October 22, 2009 at 9:11 am -  Reply

    I call BS on this one. Unless I'm understanding this wrong, you could still be mashing on the pedals, this device just applies the force to the wheel with a more average force. So in fact it encourages inefficient pedaling, and tries to apply the force more steadily. That doesn't give you any more power or speed, it just encourages poor pedaling.

    Buy some clipless pedals and learn how to ride efficiently instead.

  8. Fungineer October 22, 2009 at 11:14 am -  Reply

    So adding an undamped spring to the drivetrain is supposed to make you pedal more efficiently? Color me skeptical.

    Maybe in a certain cadence/speed/gear combination, but I suspect that under the "wrong" circumstances the spring would be feeding back in the wrong way. Think of mashing the pedals on a long travel suspension bike at low speed in the granny gear. Bicycles have to work under a large variety of conditions.

  9. Ron October 22, 2009 at 1:45 pm -  Reply

    James – The hub must be great. I won't disagree.

    But I can't agree either. I visited their page on the experiment done to show why their product is better. Anyone can see at once the insufficient amount of data and implications of this. If they give me better data and if the statistics make sense to me, I'll close my eyes and believe in the efficiency claims.

  10. eradler October 22, 2009 at 3:00 pm -  Reply

    A perfect application of the spring system would be support when starting from stand still after braking has loaded the spring…

    http://www.hyperbike.cc

  11. clever-title October 22, 2009 at 7:05 pm -  Reply

    Now I remember a similar system I saw in the 1980s. In place of a traditional chainring, the spider had 5 spring-loaded arms attached to curved chainring segments. When pedaling with more force, the spring-arms effectively made a smaller chainring, and a larger one whne pedalling with less force.

    The idea was to create a kind of automatic transmission for a bike, but it seems like it would work similarly in practice.

  12. Captain October 24, 2009 at 3:16 am -  Reply

    If it's an internal spring it is storing and releasing energy, something that is explicitly outlawed by UCI rules. I would be surprised if really has UCI approval.

    There is also a ton of research going back 20-30 years on eliptical chainrings, most of it concluding that there's no benefit. Doing the same thing in a different manner doesn't really change the physics of it. Reducing the time spent in the dead spots does not seem to equal a gain in power output.

  13. clever-title October 24, 2009 at 2:43 pm -  Reply

    I found another spring system here:
    http://www.abc.net.au/local/stories/2008/12/09/2441780.htm?site=ballarat
    which uses a spring-loaded chainring to do the same thing (store enegry during may power and release it in dead spots)

    Overall, there's no way to increase power by storing it, but some riders may prefer to have a more even power output. The real difference is little more than noise in the data when you consider the momentum of the rider & bike, so it comes down to a personal perception of comfort, as it was for Biopace.

  14. Anonymous October 27, 2009 at 11:43 am -  Reply

    Hmmm, okay someone tell my why this would release its stored energy into the wheel instead of feeding back into the legs of the cyclist through the cranks, just when the legs are at their weakest?

    About the only use I could see for this is to provide dampening of the pedal stroke when riding rough surfaces, mixed terrain, gravel, cobblestones. Even then, properly wide, lower pressure tires would do a better job absorbing the bumps.

  15. tOM Trottier October 27, 2009 at 5:07 pm -  Reply

    Would seem much simpler/lighter to have the crank arm be spring steel.

    tOM

  16. dbrower October 28, 2009 at 10:25 am -  Reply

    It seems to me that having it on the hub side of the freewheel pawls give it some opportunities missing in ones that are on the other side — in particular, no feedback into the pedals. I too am dubious about the ultimate value, but I'm not willing to write it off completely, yet.

    UCI disapproval of energy storage devices would seem to be a killer, though. For those not concerned about race legality, an e-hub that was an electric hub seems like a batter idea, and probably not more expensive.

    -dB

  17. sveti jebem November 10, 2009 at 8:42 am -  Reply

    I am from Slovenia. I heard about it, and will be very glad if this thing succeeds.

    I fear there is a lot of money in advertising and sponsorships, most probably big companies will wait until the patent rights fall and steal it.

    It is very small market here (Slovenia has population of less than 2 million, and our managers find it extremely difficult to launch a product worldwide.

    Fellow countryman Andrej Detela invented a very versatile and inexpensive direct drive electric motor. As I know is the best on the market (especially in case of mass production), but he only made a small business with Japan.
    His business partner imports cheap Chinese electric bikes in for our market.

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