nostroke

I once took a piezo buzzer and connected it in parallel with two 2 motor leads (brush motor), so it would increase the frequency based on the voltage supplied to the motor. It was very cheap and simple. And annoying! Your 3 phase brushless motors have a lot more levels of control, like speed vs torque, that I'm sure let the engineer tailor things way beyond what I can with my garden variety golf car controller, which acts like a current controller. I would love to try one. Maybe in a few years there will be an electric class in comps, or at least a forum dedicated to full sized electrics. I think I may be suffering from an inferiority complex due to having to post in the kiddie bike forum!

I guess I am sort of obsessed with the idea that at some point a pro rider will whine that electrics can't do the big launches. The design I'm working on is a sort of inside out version of a typical gas bike clutch. So instead of the primary gears being the input and the mainshaft (inner hub) being the output of the clutch, this design would use the motor shaft keyed, splined, whatever, to the inner clutch hub. Then the output would be a countershaft sprocket attached to the outer basket. The crank assy (w/ flywheel) on most gas trials bikes is around 20 lbs, the same weight approximately as the rotor on most electric motors of this scale. I think with the added inertial moment of the pancake motors relatively large OD, you could get more flywheel driven launch than a gas bike. In fact, I think that maybe the electric motor could be even lighter, maybe just 10 to 15 pounds of motor total weight with more inertia from added RPMs if needed. Anyways, this is just kind of a dream of mine, that I could make an electric that out-performs a gas trials bike and still weighs less. I think the technology is here today to do this. All that said, I really like not having a clutch to fiddle with. At my stage of riding, I'm still working on my basic balance skills, not falling over at a standstill!

My concern with doing the whoopee launch electronically is based purely on theory and not experience, so I'm kinda talking out my butt here. But I would think that a 20 pound mass spinning at 5 to 6k rpm would dump a lot more energy than most of today's batteries or electronics would deliver. My gut says that if you could translate maybe 800 to 1200 amps into torque efficiently with your electronics, it could equal the flywheel effects' massive outburst. But I doubt that a normal human could modulate that, even if you could deliver those currents efficiently. Again, this is theory, not observation, although I did ride Scorpa's earliest prototype several years ago with a very early potentiometer set up on the clutch. I expect its been electronically refined a lot since then, but physics is physics. So I still say a flywheel will out-launch most electronics, In theory. I've heard many call a BMS a battery murdering system, heh. But like everything they are always getting better.

I don't know much about the EM motor / controller. But the settings on my rig, which uses an Alltrax controller, are way simple. Because its a permanent magnet motor, there isn't much to tune. Only the throttle ramp which I do my best to fully disable. I want instant response. The touchier, the better, A lot of the newer electrics use brushless motors, which I have used in road going vehicles. Brushless motors are somewhat more efficient in terms of energy consumption. But typically, the motors and controllers are on the heavy side. And further, the last thing I want is an electrical engineer deciding how responsive I should have my throttle. I expect that is why the Scorpa and GAS GAS conversion use that (what I consider) hokey method of using a clutch operated potentiometer to make the bike more gas-like. I can see a need for a clutch when you need massive honks of torque, but it would need a real friction clutch to really do the deed, IMHO. I have modelled a friction clutch that would fit onto the motor shaft directly with no jackshafts or secondary reduction required, but have yet to build it. I am waiting until my riding skills are good enough to use that much launch! I don't use an on board BMS. I use RC car stuff for monitoring and balancing the cells, but they rarely need it. And as for over-discharge issues, I just quit riding when the power fades, which is usually a bit above the danger zone. I never pull the cell voltage below about 3.7 volts, which is very safe.

gwhy-sounds like you may have cells similar to mine, which are not really RC car cells. These are 10 AH lithium cobalt pouches. I made up two mini packs of 10S (~42V end of charge). I parallel these when I plug them onto the bike's harness. I was originally going to use 3 of these mini's in parallel for a 30 AH system, but these cobalt cells deliver the full pop, peaks of 20C (400 amps total). The down side is that these are also the cells that grounded the Boeing Dreamliner I think, ie, they can catch fire and you have to keep that in mind when storing the bike.Why they (Boeing) would chose these hot rod cells for an airplane is beyond me, but they rock for performance.

I usually ride the bike for about 1 hour before I can detect any power loss, which means its done. I could add more battery capacity but I really like the light weight and my old body is pretty hammered after 1 hour. anyways. I've built a lot of electrics, cars, bikes, trucks, etc and the first question is ALWAYS how long will it run. And there is never an easy answer because,just like a gas engine, it depends a lot on how hard you ride. But for me anyways, the run time is more than adequate, but I don't compete. There are other issues that would need to be addressed if one wanted to run with the big dogs. But as you all know, there is a big gap between just riding for fun in your back yard VS a pro event. For instance, I did not concern myself with water issues. The motor is quite exposed which helps with air cooling but would certainly have issues in competition. When I look at the designs done by Scorpa and GAS GAS, they have clearly done a better job of making their electrics water (and idiot) proof. I'll try to get a video up showing its performance. I think its pretty compelling using electrics for practice bikes. It will wheely up any hill very easily. Before I converted it, I rode it for a day and was reminded how incredibly hard it is to modulate the clutch throttle and brakes simultaneously. The electric is very easy in this regard.

I bought a used Gas Gas TXT 200 and converted to electric. I used a Briggs and Stratton E tek motor direct drive (11 / 60) gearing with a 428 chain / sprocket that I made. I use a battery pack made from RC car LiPo cells, 42 volts, 20 amphour. Am loving it, ride it every day in a residential area with no complaints. The bike weighs 145 pounds and makes just under 20 HP, lots of torque.