310 ft.lbs. torque in a 187 lb. trail bike, what could go wrong?

[Pat Conlon]

The bike boasts and brand-new drivetrain comprising a 72-V, 2.9-kWh Li-ion battery and a 16-kW motor for a very healthy 420 Nm (310 lb.ft) of instant torque at the rear wheel and a top speed of more than 100 km/h (62 mph) over three ride modes (plus a custom mode).



It's built around an extruded, forged and machined 6061 aluminum frame, has a ground clearance of 350 mm (13.78 in) and unloaded seat height of 965 mm (38 in), and tips the scales at 85 kg (187 lb) including the hot-swap battery, which reportedly gives the Bukk a category leading power-to-weight ratio.

16kW (21hp) isn't much by conventional standards but the torque # is impressive. I wonder how much more they need to be competitive with the 450's on the motocross track?

https://newatlas.com/motorcycles/cake-bukk-electric-off-road-motorcycle/

[FJ1200W]

I hurt myself looking at it -
Amazing, these times in which we live.

[RPM - Robert]

In the last two years I have seen the local PD here in town go down twice on their Zero. One turning a corner, grabbed too much throttle and the second flipping a U turn to light a traffic violator up. Luckily no other traffic was involved in either scenario but I would hate too see what more torque would look like for some of these guys with a heavy wrist as it is.

[gumby302ho]

 My 87 Ford LX 302 HO stock made 225HP and 300ft\lb of torque. I think the numbers are off. I understand max torque @ "0" rpm in electric motors
but 300ft\lb seems off and never useable for only X amount of HP. bla bla I wonder how many ft\lb that Supercharged Kawasaki H2R has. I ponder the future of electrics and like it has been mentioned here before is the controller portion, imagine controller failure at highway speeds or in town with all that instant torque picking up a bag of
milk. A silent vroom and your looking at the sky.

[Pat Conlon]

I hear ya Donnie, It's hard for me to accept these seemingly goofy power output numbers on electric motors.
1.356 Newton Meters (Nm) per ft.lb. of torque.
I have a small 14 pound electric motor on my eMTB that puts out 160 Nm of torque (which is 118 ft.lbs)
http://frey-bafang.patransformers.com/2020/06/28/bafang-ultra-max-m620-review/

To put that into perspective, my 1380cc FJ engine puts out ~105 ft.lbs at 6200rpm.

[fj1289]

I think much of the numbers are "instantaneous" and somewhat just a calculation based on dividing by an increasingly small number

HP = (TQ x RPM) / 5250    So when you calculate the torque you get

TQ = (HP x 5250) / RPM    When you take the RPMs very low (like just off idle) you are dividing by nearly zero - so the "calculated" torque approaches infinity! 

So what RPM is that 310 lb.ft at?  100 RPM?  If so torque will fall off to 31 lb.ft by 1000 RPM ... assuming constant electrical power flow to the motor

[Waiex191]

Electric motors are generally constant torque to some speed, where they achieve their power rating. After that they are constant power, so torque falls off with increasing RPM. There is no infinite torque at zero.