Electric Trials bike -Thread...

Discussion in 'Trials' started by Sting32, Nov 10, 2011.

  1. frog

    frog Long timer

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    Actually electric motors have instant torque. There is not need for spinning the engine up to get the launch. It is all there when you pin it.


    "The other performance advantage that energy has is its immediate power. Just as a battery has an immediate source of energy to run your electronics, an electric vehicle has immediate horsepower and torque. A combustion engine needs to run through the cycle of rpm (engine revolutions per minute) in order to build up its full horsepower and torque potential. An electric motor has full power the moment you press your foot on the accelerator."
    #21
  2. Sting32

    Sting32 Trials Evangelist

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    Ill argue with that, have you tried R/C race cars? the stock electric motor burns through the old nicad battery in about 4-6 minutes (yeah old tech but same principle in motion here).

    THe super fast spinning motors cut that battery time down and down. So it would seem to me, at this point in trials, the smart way to get battery life is to have a motor with windings and timing, less super fast or torqy, one that make use of the battery somewhat conservatively, then be able to wind it up and dump the clutch, like any existing decent rider, that might be in the electric market would be comfortable and or inclined to do so, today. Sure as technology advances, so will riding styles and skills in use change.

    Plus the clutch adds the same safety factor, some way to disengage that instant power/torque, if you get in trouble, etc like we do on these "hot" powered bikes we buy now...
    #22
  3. Stagehand

    Stagehand Imperfectionist

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    That ability to disengage the motor, like a clutch would, would be the best thing. Otherwise as said, gas motors do their best to mimic electric torque, but never quite get there :D

    I would have a LOT of user for an electric trials bike :D
    #23
  4. frog

    frog Long timer

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    So you are saying that by having a clutch that you can rev the bike to get torque is going to take less battery power then a small short blip of the throttle? I think it would be the opposite. Less time on the throttle without clutch in and throttle on.

    I'm not saying that a clutch is bad I couldn't ride without one. Just saying that the power of an electric motor is way different and can provide instant power that an internal combustion engine can't.
    #24
  5. Sting32

    Sting32 Trials Evangelist

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    Think about this, when your A/C comes on, it uses close to all 30 amps, in fact maybe more, for a "startup"... the circuit breaker is designed I believe, that it will withstand over power/draw for a few tenths of a second. Battery not withstanding, you draw a crapload of amps out of a batter, it is going to go dead faster.

    But if we take a motor, give it 2 times or 3 times that amount of time, to get up to speed, and with flywheel to make the motor act like a trials bike already does, you could apply the torque forces, and probably use less than half the electromoitve forces (amps) to accomplish this manuver.

    we all know I might be right on this, although I am NOT an electrical engineer, nor am I a combustion engine engineer, but we do know for fact, trials bikes have changed, we used to build 350 and bigger cc's monsters, trying to get enough power (torque actually) when you blip the throttle, the bike would react quickly and do what you do. yes, this was back in the stone ages of no stop, we didnt pull the clutch.

    In 84, fantic built an engine and bike which was ligher, quicker reving, with a little less torque than the old Bultacos I rode. the trick here was to rev and dump the clutch, so you didnt sit at the negative torque curve, on the 200 cc (240 fantic). we do the same with 80 & 125 cc bikes TODAY, which are tuned more like chainsaws than trials bikes of yor...

    Another thing, to lift my fatass cheeks over a log, or wall, where that 125 just cannot provide the instant torgue I might get with my 300/280, which I also slip-dump clutch becuase it also accomplishes loading up the suspension, which is why if you watch Tonly Bou ride in this video, http://youtu.be/jjA819GIRAw and watch for this at the 0.43 minute mark,

    (I try to attach the screen shot)

    you will see him leap from the floor, to where the rear wheel is almost above a 4 or 5 foot person's head would be... Ive seen him get higher on certain ledges, even without kickers. So dumping a clutch on a "motor" which had no load (hardly) to get up to full speed and torque, can take the torque plus it is a win win for the rider today. I admit your idea could easily come into play, when battery is lighter and stronger, and more juice, and we save some weight without clutch... right now though, I see a motor that loves to spin and sips at the battery at 5-8k rpms, making battery last longer.

    It will be neat as hell to see what they have come up with.

    I like the debate too, I learn stuff. Hope you arent taking this one as a slap or nothing, just exchanging views...

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    #25
  6. frog

    frog Long timer

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    Not at all.:D I'm not sure what will drain the battery faster high load-short runtime or low load-longer run time. Thats why we have engineers.:lol3

    I'd love to see a full size electric trials bike. That way I could ride with my kid on his OSET and not bug the neighbors.:evil

    Hopefully batteries will get better because thats the only thing that I don't like about the OSET.
    #26
  7. BikePilot

    BikePilot Long timer

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    Sting's point is the one I tried to make earlier the point of the clutch is more about accelerating a bunch of mass, storing a ton of energy in that mass, then dumping it to the rear wheel all of the sudden than playing with torque curves.
    #27
  8. frog

    frog Long timer

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    And that is what electric motors do without any wind up. Max torque from 0 rpm. The energy is all stored in the battery.
    #28
  9. BikePilot

    BikePilot Long timer

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    That is what electric motors do yes, I know that. Everyone I know knows that. I think, my pet bird knows that, and its NOT what I'm talking about. :lol3

    Having a clutch allows you to do two things that you can't do without a clutch, regardless of your torque curve. First, it allows you to store energy in a flywheel. When released, the total available energy you can apply to the rear wheel is that stored energy + the torque of the motor. Assuming that your electric motor can't efficiently, completely deplete the battery in an instant (which, if it could would be a whole 'nother problem:lol3), this is necessarily more than the torque of the motor alone, no matter how much torque the motor can make. So, all else equal and no matter what type of motor you have and no matter what sort of torque curve it makes, you can apply more torque to the rear wheel if you have a clutch than you can without a clutch.

    Second, it allows you to get moving parts (electric motor rotor, crank, gearbox bits, flywheel, whatever) moving before you get the wheel moving so less torque is required to get the same result in terms of accleration. When you want to get going you've gotta do three things. First you've gotta accelerate all the moving bits in your drivetrain, second you've gotta get the rear wheel moving and finally you've gotta actually get the bike moving. All we really care about is getting the bike moving. Provided again that you have enough battery to run the motor at full torque for more than an instant, you can split these three things up and attack the first (in part at least) first, then do the latter two at once. So if say it takes 3ft/lbs of torque to accelerate the spinning bits in the motor itself at the requisite rate of speed, that 3ft/lbs is freed up and available to apply to getting the wheel spinning and bike moving, if you get it spinning before you actually need to apply torque to the wheel, making the bike accelerate as though its motor had 3ft/lbs tq more than it actually does.

    Whether either of these is necessary with an electric motor is definitely an open question.
    #29
  10. frog

    frog Long timer

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    You are thinking too much about the things you find on gas bikes. Flywheels, gears, piston, etc. Without gears flywheels and other things that need to spin up there is no need to rev the bike. You can get explosive power just by turning the throttle.

    Do me favor. Go out in the yard, Hold the clutch in and gas open. then dump the clutch. When I say dump it just let go instantly. You will spin the tire or flip the bike. You never just let go, you apply the power fast but not instantly and not all the power the bike has. the reason for the rev up with clutch in is to get the piston moving, flywheel moving, clutch basket moving. If there is none of that to spin up then why would you need to rev the bike?

    And no you don't need to deplete the battery in one shot... Do you use all the gas in your tank in clutch dump?

    check this out no rev up and looks like it has plenty of stored energy.

    http://www.trial-club.com/webzine-t...nfo/?tx_ttnews[tt_news]=8393&cHash=a67f46a973
    #30
  11. Sting32

    Sting32 Trials Evangelist

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    My thoughts/point I thought was, sorry if it didnt get out, that the energy draw, to take a motor, connected to the rear wheels, was going to be like starting a rather BIG air compressor, which takes a crapload of AMPs, for mayeb a litte time, but I think significant time. When we play with our R/C cars, even the older ones with nicads, I feel but cannot refute, that if I drive around the yard, at half throttle or less (like a trials bike) dont stop and start, the battery lasts quite a bit longer than when I race back and forth up the 40ft driveway.

    So my thoughts were if my electric truck, had a clutch, the motor never had the draw so many mAh's just to start the truck into motion, then maybe battery would last longer? I thought I read about the equasion of theory that using more than 10% of a battery's total amp hour rating for even small bursts, draind the batteries by more than 20% ( meaning greater losses with higher amp draws) than if the amp loads are kept off peak juice sucking, battery will last and hold caharges longer?

    I also know from camping, that I can run about 6 12v lights, and the heater, along with ONE 12volt car battery sized deep cycle battery, for 2 days. If I leave the lights off, this whole time (use flashlights and lanterns) I get closer to 3 days. if I dont use the heater, I get 5 days of camping and more (havent camped that long for a long time).

    Heater draws lost of energy, to start up several times a night/day where lights us a little all the time the few hours you might use them.

    If I could find that article I read, I would have posted it darn it. The artilce was nice, showed the bell curve of amps, to start any "motor" into motion, the "stonger the motor's accelration" the more you had to multiply the curve, but it was obvious that for 0-10% of the rpm of a motor, the amp draw was at highest draw? then it leveled out a bit, then of course full RPM met the high draw again, but the level it dropped, where mid ranges or design "workable" or favorable RPM, could be modified by brush and magnet and winding (timings) to produce hellish torque, RPMS, and breaking? Almost like we do now with carbs, exhaust and Jetting, I think...

    Some kind of speed controller design, for RC I think, I will hunt again if I can find more time, they could been wrong too, and just bsing about how good thier electronic controller and motors were :p
    #31