HSD drive for bicycles

Discussion in 'Prius, Hybrid, EV and Alt-Fuel News' started by richard schumacher, Nov 28, 2005.

  1. richard schumacher

    richard schumacher shortbus driver

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    How to convince Toyota to make or license an HSD drive for bicycles?

    Like internal combustion engine, human legs work best in a rather narrow range of speed and output power. An HSD system could more optimally couple human output to the bike wheel and provide energy storage, regen braking and electric assist. Getting rid of the derailleur and exposed chains would be nice also.
     
  2. hyo silver

    hyo silver Awaaaaay

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    There are electric bicycles, but none that I know of with regenerative brakes. The big problem with them so far, imho, is the weight of the batteries. When the range and speed of an electric bike is less than an ordinary bike, it doesn't make alot of sense. Bikes already have batteries - they recharge overnight, and last about 100 years if treated well. (Plugging them in is fun too!) More can be gained with streamlining, as in recumbent with a fairing. Chains are actually very efficient, and aren't nearly so objectionable if you use parrafin as a lubricant instead of that slimy sticky stuff. There is apparently a newish trainer that uses a sealed-fluid magnetic drive, which conjures up all sorts of possibilities. I think rare earth magnets may have a use in bicycle propulsion (and braking) in the not too distant future.
     
  3. altaskier

    altaskier New Member

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    Hard to imagine who would want it. On a bike, weight is key; people will go to incredible lengths to shave off ounces, and batteries are about the heaviest way around to store energy (batteries suck on a kg mass/Joule stored energy measure). A good quality chain and derailleur can function quite well without problems. The whole idea of having a bike with many gears (mine has 18, though most of the time I only use about 5 of gear combos) is that you can you shift gears so that you can pedal at a near-constant cadence and with near-constant power output. If you're going up a hill, your speed is slower, and if you're on a flat, it's faster - but you can always go at your huff-and-puff limit if you use your gears properly.

    I like hyo silver's comment about how fun it is to plug in the "batteries" already used on bikes! Just got to watch for circulation around the saddle area...
     
  4. SlipperySlope

    SlipperySlope New Member

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    Even regenerative braking (say with compressed air or mechanical spring) would not be practical on a road bicycle because of the additional weight. It is simply more difficult to ride a heavier bike due to rolling friction. The majority of bicycles are ridden for exercise where the energy lost while braking downhill is part of the sport.

    However, a choice for commuters is a motorscooter and these could be plug in hybrids for maximum fuel efficiency. In India, both motorized two and three wheelers are used for commuting in large numbers.
     
  5. richard schumacher

    richard schumacher shortbus driver

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    I think there's an unrecognized market here. Surely some number of people would like a bike that permits them to exert whatever combination of effort and crank RPMs they want but not have to fiddle with shifting (of course the road speed would not be constant). The design intent of such as system is to appeal to people who may not now be bike riders: a bike that's as easy as possible to use, providing any desired level of outdoor exercise but capable of power assist as needed.

    As you point out, plug-in recharge electric bikes are available now, but they amount to electric motorcycles; a hybrid bike serves a different purpose. A hybrid bike would also obviously not be a product for the lycra suit crowd, but it would have geek appeal for a different kind of geek.

    The necessary battery would not be very big, only enough, roughly, to get the rider up one hill. And once you have electric drive and a battery, braking regeneration is free.

    This functionally already exists, more or less, in a few bolt-on motor assist systems. Desiging one from the ground up would allow optimization and (geek factor here) an enclosed drive train with no exposed gears, no chain, and no derailleur.
     
  6. bobr1

    bobr1 New Member

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    Besides the problem of weight, there is also the problem of energy losses.

    Energy is lost every time you change modes... in this case going from mechanical energy input to electricity to charge the batteries or run the electric motor... regenerative braking loses energy twice, once from converting mechanical into electrical, then when converting electrical to battery storage.

    In all cars, energy is lost in many ways. The solution is almost always to throw more gasoline at the problem. As it happens, hybrid systems using electricity, despite the losses due to mode change and storage, are an improvement because gasoline engines are wasteful except in a narrow RPM range.

    The problem with applying such technology to a bicycle is that the gasoline is replaced with human leg power, and therefore _you_, the rider, will be directly suffering the consequences of energy lost due to mode change. The benefit of the hybrid system may not be efficient enough to make up for the mode change losses... translation: You may actually get more tired sooner riding one of these hypothetical bikes.

    Of course, the wonderful thing about hypothetical inventions is that we get to argue about them without consequence until somebody actually builds one. :)

    - Bob R.
     
  7. TimBikes

    TimBikes New Member

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    Weight is a key factor for "the lycra suit" crowd and cost a key factor for the masses. So either way I don't see the appeal going much beyond the geek crowd, as you say. However, since we are dreaming here, I'm wondering if a mechanical solution would be more efficient. Perhaps a spring like in a watch or clock that gets engaged when braking (and thus wound up) then released by a simple lever when you need a small bit of extra push to get you up a hill.
     
  8. dipper

    dipper Senior Member

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    uh guys. Not to burst your bubble.

    There are electric assist bikes with regen braking already.

    The top of the line is called the Wavecrest M-750 (and S-750). These bikes have 750Watt motors on them (500W for Canada). They were originally built for the Army. And then the police used them. It is now available for the general public.

    Wavecrest invested a lot of money in electric hub motors to try to sell to auto makers.
     
  9. hyo silver

    hyo silver Awaaaaay

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    Hot damn, so there are. Thanks, dipper!

    PS Any way to disable the governor? For someone like me who wants a bicycle speedometer with three digits (I live near some very large hills), 20 mph isn't going to make me part with 3 grand.
     
  10. usbseawolf2000

    usbseawolf2000 HSD PhD

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    I thought about this idea a while back too. I am not sure HSD bike would work.

    In Prius, the computer controls MG1 and ICE. In the bicycle, it would be MG1 and human legs but computer can't control the legs. It could work if the computer command the cyclist to paddle slower or faster with a display. Imagine, you want to go faster and hit the accelerator. Computer would signal you to signal to paddle to a certain RPM.

    Is that how you envison HSD bicycle or you have completely different idea?
     
  11. davek

    davek New Member

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    Kinda related.



    I race mountian bikes as a hobby and CVT was played with by a couple companies.

    Honda supposedly experimented with a CVT on a coupe factory race bikes, but ultimately went back to derailluers.

    It's simply too much to do on a bike. Who the hell wants to work on a CVT? On a bike? Yeah right.


    Honestly, if you're too lazy to climb a hill on your own power, get a motorcycle. That's what you want right? Something to power your bike for you?
     
  12. tdi2prius

    tdi2prius New Member

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    I used to ride an electric bike in Las Vegas with regen. My poor 81 Celica got clobbered by an SUV and I was too broke to get new wheels. It was a blast -- plenty of drivers smiling and rubbernecking when you're cruising on level ground without pedaling. I stayed on the sidewalk to be safer.

    Now, the new ZAP units require pedaling to activate. Too bad. It was perfect for me with a seven mile one way trip on the valley hills especially after work when I was going uphill in 110 degree heat. I recharged at school in the classroom during the day and it was actually pretty efficient in terms of time spent in traffic.

    http://www.zapworld.com/products/dxkit_bike.asp
     
  13. dipper

    dipper Senior Member

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    Since you asked. There is an option to disable it. From what I heard, you have to sign a waiver saying this is not going to be use for street.

    By disabling the governor, the power gets to be 1000 watt. The top power is around 35mph without human assist.

    This bike is really an electric bike with human assist, not an electric assist bike that it is marketed as... :lol:
     
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