Electric bicycles with high acceleration (Harley, ride, custom, bike)
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Recently I became interested in electrically-assisted bicycles, whether as a stand-alone model or a retrofit kit to an existing bicycle (a mountain bike with front suspension). But what gives me consternation is the power levels. Even 1500W is “high end”. But consider this. A fully laden delivery-van might weigh 10,000 pounds, and in the worst case have maybe a 100 hp engine. That’s a power-to-weight of an abysmal 1:100. Even the slowest economy-car from bygone days might have 40 hp and weigh say 2400 pounds, for a power-to-weight of 1:60. That’s from the 1940s.
Well, for a 200 lb rider on a 50 lb (if it’s very light… more like 100 lb) machine, with no cargo or weight accounting for safety equipment etc., that’s at least 250 lb gross-weight. To keep up with the wheezing, barely-accelerated delivery van, this machine would need 2.5 hp, which is already above the most powerful 1.5 KW electric motor advertised for e-bikes.
Have you looked at Zero electric motorcycles? The Zero SR can go 0-60 in 3 seconds. They have really impressive range too.
Yes, but what I had in mind was bicycles - a vehicle that I could lift with one arm and carry multiple flights of stairs... but which had on the order of 5-10 hp, and which could accelerate sufficiently rapidly as to keep up with modern sedans/trucks/SUVs on city (not highway) roads, up to maybe 40 mph.
Yes, but what I had in mind was bicycles - a vehicle that I could lift with one arm and carry multiple flights of stairs... but which had on the order of 5-10 hp, and which could accelerate sufficiently rapidly as to keep up with modern sedans/trucks/SUVs on city (not highway) roads, up to maybe 40 mph.
I just bought an E bike a couple months ago and love it.......it's not lightweight (70lbs) and it tops out at around 20mph. Nothing in the regular E bikes will do 40mph and the problem is in the brakes, and also regulations......most of these bikes are limited to 20mph by law. Offroad you can go wild. My guess is going 40mph on a light bike you could carry up stairs with one hand would kill you quickly. For a short commute of less than 10 miles these bikes would be great, you could arrive and barely break a sweat.
I just bought an E bike a couple months ago and love it.......it's not lightweight (70lbs) and it tops out at around 20mph. Nothing in the regular E bikes will do 40mph and the problem is in the brakes, and also regulations......most of these bikes are limited to 20mph by law. Offroad you can go wild. My guess is going 40mph on a light bike you could carry up stairs with one hand would kill you quickly. For a short commute of less than 10 miles these bikes would be great, you could arrive and barely break a sweat.
The intention would be a <10 mile commute, but that includes substantial hills. And ideally I'd be treated as a car... accelerating as a car, holding speed as a car, stopping as a car, signalling as a car... I'm a car, on two wheels, with a vehicle that's sufficiently light as to be carried upstairs upon arrival. I'd do this mostly for convenience and enjoyment - not for reasons of fitness, environmentalism, new-age urbanism or fashion.
And as for acceleration, the dream would be enough power (torque and appropriate gearing) to lift and carry the front tire, despite me leaning forward over the handlebars. 0-30 in well under 2s.
You're looking at ebikes in a price range of medium displacement scooters. That or building one, in which you're gonna want to do some math on how much power, range, top speed and cruising speed, which means custom building battery cells to make a battery and then figuring out the right controller and smart charger. And also need to take note if you're going to be using a mid-drive(which makes good use of gears) or a hub drive. Then you have two types of hub drive; direct and geared. And once all that is done; the bike is going to be heavy and you're not gonna want to be lugging it up too many steps. If you meant a 50lb bike before being outfitted... that's a heavy bike. My 83 Schwinn High Sierra is only 30 something lbs. I can't stand carrying it up my steps every day.
You're looking at ebikes in a price range of medium displacement scooters. That or building one, in which you're gonna want to do some math on how much power, range, top speed and cruising speed, which means custom building battery cells to make a battery and then figuring out the right controller and smart charger. And also need to take note if you're going to be using a mid-drive(which makes good use of gears) or a hub drive. Then you have two types of hub drive; direct and geared. And once all that is done; the bike is going to be heavy and you're not gonna want to be lugging it up too many steps. If you meant a 50lb bike before being outfitted... that's a heavy bike. My 83 Schwinn High Sierra is only 30 something lbs. I can't stand carrying it up my steps every day.
I am musing about a ~3-4KW mid-drive. Battery and controller would be adapted from R/C electric aircraft, where I have some experience in the ~10KW range. The baseline bicycle is a mountain-bike from the 1990s, with front suspension (but not rear). Assuming a 25C discharge rate, the battery can be kept light, if (1) the range only needs to be maybe 10-15 miles, and (2) full power is only needed for bursts of 1-2 seconds, every minute or so.
The duty-cycle would be: (1) at a stop-sign, engage full power, until reaching 25-30 mph; (2) coast; (3) apply maybe 1KW (if that; maybe less, on level-ground) to maintain speed; (4) slow down (regenerative braking?) for next stop-sign; (5) repeat for another ~20 blocks.
The motor, battery and controller would together weigh maybe 25 pounds (generously). I have no idea about the weight of gears, chain, mounting hardware and whatever brake upgrades would be needed.
I need to dig up the thread, but there was a user on the endless-sphere forum that built almost exactly what you had in mind. It used an R/C outrunner mounted using a friction drive. The inertia of the spinning motor twisted it into position and drove the wheel, and when off, a spring rotated it out of the way. The ESC and the motor were mounted on the bike, but the battery was just a plain lipoly that he kept in his backpack and plugged in. The total added weight was just a few pounds. He had it mounted to a road bike near the pedals, so it was nearly imperceptible since the whole package was so small.
Definitely not in the 1,000+ watt territory, but you really only need ~400w to get up a hill and go 15-20 mph if you keep the weight down. I'm shooting in the dark but maybe his was 600w?
...Definitely not in the 1,000+ watt territory, but you really only need ~400w to get up a hill and go 15-20 mph if you keep the weight down. I'm shooting in the dark but maybe his was 600w?
Considering that a healthy human outputs maybe only 250W, indeed, high power isn't required for pedal-assist. But where I'm aiming is to build more of a bicycle-based low-speed motorcycle. Its intent is to be fully viable in traffic (not on highways, of course), holding speed and accelerating at least as well as a modern car. For some reason, the electric bicycle market doesn't seem to be interested in such an option.
Considering that a healthy human outputs maybe only 250W, indeed, high power isn't required for pedal-assist. But where I'm aiming is to build more of a bicycle-based low-speed motorcycle. Its intent is to be fully viable in traffic (not on highways, of course), holding speed and accelerating at least as well as a modern car. For some reason, the electric bicycle market doesn't seem to be interested in such an option.
Then it wouldn't be a bicycle. It would be a motorcycle. The Zero is your best bet. Harley Livewire too!
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