I don't know. The equation for power needed to propel a bike at a certain speed is mostly calculating the aerodynamic drag, which rises by 4x as speed doubles. At 28 mph, the power is around 750 watts. The speed pedelecs that Haibike is going to sell seem to have 350 watt motors. If you have 350 watts available, I'm not sure how they will get the 750 watts they need to go at the SP limit. Not too many riders can supply 400 watts for very long. A race frame would help.Ummm, folks, it's still a 350 watt hub motor, no matter what the windings but with a nice battery. A 350 watt mid drive produces more torque and power than this hub motor so its not a one-to-one match with the Izip Dash.
Good point about the maintenance on the hydraulic disc brakes, Ann. There's certainly a trade-off there. My S-pedelec with mechanical disc brakes is screaming for a set of beefier hydraulic discs, and it seems like all the s-pedelecs are going hydraulic because customers want that stronger braking feel.Ummm, folks, it's still a 350 watt hub motor, no matter what the windings but with a nice battery. A 350 watt mid drive produces more torque and power than this hub motor so its not a one-to-one match with the Izip Dash. Hydraulic brakes, nice upgrade. If you have extreme downhills in your ride, needed. If people would maintain the components and take the time to learn how to adjust their brakes, standard disc brakes work great and are less sensitive to extreme temperatures. It's no fun to work on a set of hydraulic brakes where the owner has left the bike stored somewhere hot for months on end or has to leave it in the direct sun all the time, then the fluid is goo in the lines and the brakes practically frozen. More expensive for the customer, too. Remember, hydraulic brakes have more components that can fail (a small master cylinder just like in a car's brakes)
Good point about power requirements. I've often wondered how those Bosch S-pedelecs hit 28mph. I'm not certain, but I think that you don't need as much power to get to those speeds. I think 400W-500W would suffice to reach 28mph with some average pedal input, and that's quite doable with a 350W (nominal) motor. My 500W (nominal), 750W (peak) rear hub motor bike can hit 32-34MPH on flat ground with heavy pedal input and a low, aerodynamic body position, but if I were using your assumptions about power and speed, then I would need 1,000W+ to hit those speeds, and I just don't think my bike has that much power, even at peak output. Perhaps there are more variables here that complicate things...perhaps my aero body positioning gives me more speed that isn't factored into your power/speed model. And I'm also pedaling quite hard to reach those speeds, and one cannot maintain that forever.The equation for power needed to propel a bike at a certain speed is mostly calculating the aerodynamic drag, which rises by 4x as speed doubles. At 28 mph, the power is around 750 watts. The speed pedelecs that Haibike is going to sell seem to have 350 watt motors. If you have 350 watts available, I'm not sure how they will get the 750 watts they need to go at the SP limit. Not too many riders can supply 400 watts for very long. A race frame would help.
When someone says they are designing a 30 mph bike, it makes a lot of sense to use a 1,000 watt motor. That is what Bafang is offering, a 1,000 watt mid-drive. It would be very easy, and pretty cheap, for JR to provide a 750 watt motor. Several things on their web page for this bike need fact checking.
It would be fun to know which design path is better. Do you want a basic mid-drive like the Curry, which will probably do well on hills? Do you want motors with the raw watts to go faster? A 20 mph bike is around a 350 watt bike, but getting to 28 mph doubles the power requirement.
Hi,The motor is "350W" but can hit 650-700W peak and get to 28-30mph with no problem. The watt number stamped on the motor is just a reference capacity and not a dyno reading. On the CrossCurrent the power is more limited by the battery's continuous output, not the motor really. We tune the controller so the bike can give a satisfying ride without draining the pack immediately and giving it a short life. Its a balance.
A mid-drive produces more torque for better hill climbing since you can use the bike's transmission, but has some drawbacks at the moment for the scope of the CrossCurrent's objectives. In exchange for pulling trailers and flying up steep hills, the CrossCurrent returns you a relatively light bike for assisting you at 24-30mph comfortably.
It's easy to make out the numbers if you pause the video. It was clearly running around 27 mph with over 600 watts going through the system at the start. So the Bafang is capable of delivering what you need for that Class 3 California standard.We have been doing the range testing with the production spec CrossCurrent to get the real range figures. We attached the GPS and battery power meter (Cycle Analyst) so we can record the information. Here the CrossCurrent is tested in SPORT mode up to the top speed of 28mph. It does require some pedaling to help it achieve top speed, but the motor has fast winding so it does not start to work against you at those speeds like other bikes. The controller is tuned to hit the S-Pedelec performance targets with some assistance from the rider. After those speeds, the wind really slows you down and you need to dump much more amps to get any little bit faster.
Sorry for the video but trying to do this with one hand pedaling and changing gears.
If the 7.8 ahr /48V pack is 5lb, the 23 ahr will add 10 lbs and won't look as slick. Just sayin'.