GreenWheel: Swap the rear to make any bike electric

The "GreenWheel" lets you turn a bike into an electric simply by swapping the rear wheel. The batteries and motor sit inside the plate at the axle, while the throttle control operates wirelessly through Bluetooth. At full charge, the GreenWheel has a range of around 25 miles, extended by the pedaling of the rider. Discovery News:
A GreenWheel equipped bike is a smooth ride, as Discovery News found out during a recent afternoon test ride around MIT's campus. Turning the handle mounted throttle, like any motorcycle, just a few small degrees produces a noticeable increase in power and a light electric hum.
The inventors estimate a life of nearly 40,000 miles, which is pretty incredible. They're trying out different sizes and power ratios and hope to have a product on the market very soon.
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32 Responses to GreenWheel: Swap the rear to make any bike electric

  1. bazzargh says:

    @6 I won’t miss the extra wind in my hair, since I’m bald as a coot. Though it’d obviously be less *fun*.

    I have to agree with the skepticism on the battery life. Also, taking an MTB/Hybrid and adding electric would make it 40lb ish, always seemed counterproductive when you can get a 20lb-ish road bike and make pedalling (and carrying) the bike far easier.

  2. jenjen says:

    I like that this looks like it wouldn’t be obviously an electric bike if you’re pedaling. I’d be interested in something that could give me a little help up a lonnnnnnng hill (lazy? guilty.) but not have cops stopping me and asking where’s my motorcycle license.

  3. TikiHead says:

    Nougat: that Amped Bike kit looks really cool — I have seen other hub motors out there that allow 40+ mph speeds, but then you are inviting death or a traffic ticket.

  4. mightymouse1584 says:

    the perfect way to give your bicycle a carbon footprint;)

  5. mdh says:

    NutBastard – Should you ever meet Critical Mass, just be yourself.

  6. larsrc says:

    The GreenWheel is also durable. The team estimates its range at 40,000 miles, or about eight years work of travel at an estimated 20 miles per business day.

    “You’ll have to replace the bike before you replace the batteries,” Lin told Discovery News.

    These guys need better bikes. Mine is now nine years old and still going strong. Granted, I have replaced the rear wheel onces and the gears several times, but still…

  7. Chuck Steel says:

    Yeah, how is this greener than just pedaling? Shouldn’t it be called the LazyWheel?

  8. TikiHead says:

    As someone who has ridden an e-bike for years (Unlike the rest of you, but I am sure your opinions count more than mine!), I can tell you it’s been worthwhile. I can commute the four and a half steep, hilly miles to work in reasonable time, and not arrived so drenched that I require a shower. My bike is a different version than those shown in the article, in that on mine you must pedal at all times for the motor to assist you.

    When my truck was totaled by a drunk driver, that bike made my life bearable — I used it for all transportation needs. Thank goodness I live close to work, and have numerous stores nearby.

    I don’t want to be accused of posting spam, but my bike brand is the Charger.

  9. nixiebunny says:

    I rode an electric bike for a while, and found the reliability to be not so good. The motor’s controller burned out after about 18 months, and it was a non-repairable sealed unit.

    I also found that a 10 mile range at 15 MPH on a 24V 12AH battery pack was about all it could muster. How they get it to go 20 miles at 25 MPH with that small of a battery pack inside the hub is beyond me and/or the laws of physics.

    The 40,000 mile battery life claim sounds hokey too. I got about 2000 miles out a lead-acid pack, and Li-ion are notorious for failing after a couple years whether or not they are used. Perhaps these folks have some magic batteries that will survive 1000 charge cycles while living right next to a hot motor?

    So… I’d like to see the MIT engineering report on this product.

  10. Anonymous says:

    @Chuck Steel:

    In theory, this device should substantially increase the effective range of a given cyclist, and thus the number of trips they can take by bike, as opposed to some other means. In practice, there probably will be more than a few that end up shoving the increasingly lardy payload of aging hipster from point A to point B.

  11. The Life Of Bryan says:

    @14: Would you fine car-driving folks please be so courteous as to post the times somewhere so that us douchebags know when it’s alright to utilize our tax dolla– err, roads?

    Oh, and just to confound the assumptions of people like you, I commute to work wearing spandex. And sometimes $75 merino wool t-shirts.

  12. gwydion says:

    I’m a bit surprised at some of the criticism here against electric bikes and their proponents. For some folks who are looking to try to be more healthy, but live in areas where the hills preclude biking for anyone but pros, it’s really the sort of thing that could make the difference between getting exercise or not. The case could be made that such individuals would get better exercise by pushing themselves to the limit trying to roll up a large hill – and it’s that sort of thinking that shames people into not ever even trying to get exercise, because they end up having to walk their bike up hills. Trust me, I’ve had to do that on many occasions and it feels embarrassing, even though it shouldn’t be.

    Anything that makes it easier for any of us to get/stay healthy helps us all. Anything that saves any of us even a few car trips – let alone a daily commute – helps us all. Really, it’s just unfortunate that folks would be so dismissive or even annoyed about something like this, which I consider a no-brainer.

    As for the carbon footprint thing… Seriously? A person who gets physically fit would (to my mind anyway) have more incentive to eat less and eat healthier (big eco-saving right there), and the savings alone in avoiding a car trip would seem to make it totally worth the battery disposal issue.

  13. bazzargh says:

    Slightly better information here:

    I keep seeing the obvious question asked, does it have regenerative braking. All the pics show normal brakes attached to the new wheel, so you might think not, but here Michael Lin is quoted as saying it does.

    This article hints at an explanation – they have a chip to detect the incline the bike is on, so presumably it automatically switches into regeneration on downhills, without manual intervention.

  14. Anonymous says:

    Hi Kids, New here, (so go gentle I should probably research before commenting) I was wondering,
    Are there stationary bikes available that are able to charge up home devices so that we are less dependent on electricity? I vaguely recall around New Years seeing people in Times Square, riding a bike to donate the power to drop the ball.
    It would be cool to get some needed exercise and lower my electric bill at the same time.
    Or would it be too expensive to mass produce? Go gently… EFT4MeDebi

  15. mdh says:

    They’d better include a couple hard-points to lock it on with, and/or make the bulk of it quick release. Flexibility to add solar cells or to wall charge couldn’t hurt either. 40K miles is impressive.

  16. The Lizardman says:

    @15 If the cops are stopping you on something like this for a motorcycle license it is an obvious pretense for harassing you over something else. Most places don’t require a motorcycle license for vehicles under 50cc and I don’t know of anyone who has even been pulled over on a scooter without doing something that demanded the police take an interest (eg riding naked and/or wrong way down a one way street). Point being, I think your worries on that front are probably unfounded.

  17. Paul Freedman says:

    I agree with many of the posts. I am not lazy but I have a broken back and pins in my legs that do not allow me to ride a bicycle normally. I am not lazy and his is what caused my injuries (by over doing everything).

    I purchased an kit and am very very happy with it. What happens to me is the pain settles in for a few minutes and I don’t have to stop or reduce pace. I just keep going on battery until the pain is gone, then ride more.

    This has really opened up a new world that I thought has been long gone for me.

    In any case this would be excellent for the over weight, for some that are a bit unhealthy to get them back outside and the elderly.

    It promotes exercise 100% but when tired or in pain you can simply cruise on battery power.

    Top notch tech in my humble opinion.

    I don’t think bike riding should be only for the super healthy. I think the joys of biking should be for everyone.

  18. The Lizardman says:

    @1 The manufacturing of your bike already gives it a pretty good footprint, I would guess.

    I’d rather walk, being on the road with most car drivers is bad enough on a scooter or motorcycle, with a bike I just feel like I am asking to be killed.

  19. hohum says:

    I would like something like this, or more realistically, I suppose, like what #10 posted. Although I’m still not comfortable parking my Bianchi anywhere in the city. I want so much to be an urban cyclist, but I just see too many bikes-turned-scrap-piles chained to meters, bike racks, etc…

  20. TikiHead says:

    @ #19 Halloween Jack — yeah, same here, and I can’t speak for the GreenWheel, but I have not yet had to ride home with a ‘boat anchor.’ I just recharge when I get to work, recharge when I get home. I am paranoid that way. My battery pack gives me about 15 miles range per charge on full assist: I just don’t push it.

  21. dustbuster7000 says:

    @6 – Well it could be configured that way, but that might make freewheeling downhill to gain speed a bit difficult if its robbing you of energy to fill the battery. Regenerative braking on a bicycle is not going to be of much use under any other circumstance (ie. braking on level ground), simply because a bike and rider don’t weigh that much, so there’s a limited amount of energy to be recovered. But its an interesting idea nonetheless.

  22. Anonymous says:

    @30: How much of your roads are paid by gas taxes, and how much are paid evenly by all people, including cyclists? The question is, why are tax-paying cyclists subsidizing roads for drivers? Especially highways they aren’t legally allowed to use?

  23. Nougat says:

    If these are reasonably priced I want one.

    I enjoy biking to work yet must appear unsweaty and reasonably well dressed. If I could commute without needing a change of cloths and a shower when I arrive I would happily start pedaling home and perhaps get some of the exercise my eight hours at a desk demands.

    I almost bought one of these kits whit this in mind.

    $360 shipped plus battery

  24. nixiebunny says:

    I looked through the Googlesphere for actual information about this device, but there’s only a tiny 150 pixel square image of an exploded view, from an article from last October.

    The MIT Media Lab’s Smart Cities website has absolutely nothing on this gizmo, which is curious given the amount of press it’s getting.

    I think it’s another case of Big Detroit suppressing the magic 270 MPG carburetor.

  25. MB says:

    Bluetooth throttle control? Yeah, I’d want to rely on *that*.

  26. SlightlyMadScience says:

    My biggest issue with the design is how are you going to charge it easily? If the batteries are in the hub, you’d have to charge it where the bike is – and that’s not always easy – especially when commuting to work.

    I agree with reservations about the a battery fitting inside that hub and having any decent range. Don’t see that as possible even with lithium.

    I currently use a recumbent trike with a 36 volt motor. When I ride to work, it’s nice to be able to disconnect the batteries and charge during the day at my desk.

  27. Halloween Jack says:

    I’m in my mid-forties, and I wouldn’t mind a little extra oomph when going up the bluffs where I live after a long ride, but I’m a little suspicious when the only detail that seems to be missing is the device’s weight. I’d hate to find out that the battery life has been a little exaggerated and that I now have to drag a boat anchor attached to my back wheel home.

  28. Julian Bond says:

    I have a lot of trouble believing these claims compared with this
    Hub motor which fits pretty much any front fork. Several battery options. Neat design. Not stupidly expensive.

    Fitting the batteries inside the hub and getting useful performance? No way. At least not with 2009 battery technology.

  29. sg says:

    Yeah, I understand that this e-bike is all teh sexy because you can’t actually BUY one yet. But now that Joel is kicking it PNW-style in my great state of Eugene, I thought you guys might like to seek how we keep it realz out here:

  30. TikiHead says:

    @ #23 Nougat: the Charger is $800 for the complete bike (though I ran right out and bought a shock fork and shock seat post.

  31. nutbastard says:


    “in the end, more bikes on the road generally means less congestion”

    Not if you’re driving with a bunch of slow ass bikers hogging the road in front of you. We get huge lines of cars backed up because Johnny Douchebag, who apparently doesn’t have anywhere to be at 8am during the week, decided he’d spandex himself up and ride down the hill at 25mph in a 45 zone during morning rush hour.

    If you’re commuting on a bike, fine, but the recreational bikers need to stay the hell off the main highways during the commute.

  32. Dr_Wally says:

    I used to frown on electric cyclists as a ‘real’ cyclist myself, but in the end, more bikes on the road generally means less congestion and less pollution.

    And every extra cyclist on the road increases visibility of cyclists as a whole. So those ‘not going on the road, going to be killed’ complaints are self-defeating.

    Even if you’re only pedalling on this thing half the time, the health benefits are desirable.

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