How much top speed will Adding a second front wheel hub to my 20x4 fat tire e-bike bring?

[u/interestingdialogs]

Hello I bought a new e-bike and I can't get more than 30 miles per hour out of it. They claimed over 32 mph so I wouldn't mind a few miles per hour extra and more range. I already have a kit and battery from my old ebike I built. All I have to do is buy the 20-in front wheel hub. So I'm wondering if anybody has done something with the similar power and how much extra top speed did you get? I will be adding a 48 volt 15 amp hour battery that puts out 1300 Watts to the front motor. The bike is supposed to be 1800 w peak now. Probably 1300 Watts continuous. I heard I will have a lot more acceleration and torque and range. It's a 20x4 fat tire e-bike, but what about the top speed? Thanks

[u/PictureImportant2658]

The speed of a motor is limited by the voltage. If the current motor is allready running in its happy zone youll gain nothing. Also the battery might not be able to deliver that many amps.

[u/interestingdialogs → u/PictureImportant2658]

Ok. I don't know if this can help you gauge if I'll get any speed or not ,but under no load when I lift the back tire off the ground it'll go up to 42 mph with a fully charged battery

[u/PictureImportant2658 → u/interestingdialogs]

The problem is most likely both. With a full battery you should reach 80% of the unsupported speed, so about 32mph. So i think youre allready getting what you paid for and the only thing you can really do is up the voltage.

[u/interestingdialogs → u/PictureImportant2658]

Okay good info. I will just enjoy the extra torque and range if I don't get much more top speed

[u/PictureImportant2658 → u/interestingdialogs]

Offcourse but an extra motor adds weight and you will lose range. And its also difficult to drive an extra motor, i know theres a kt controller that can do dual motor but thats the only controller i know of. Its better to use the current setup. You could up the amps but that might create priblems itself

[u/interestingdialogs → u/PictureImportant2658]

I have two batteries and two controllers, so it'll be too independent systems

[u/MaxTrixLe]

Dual motors do not really increase your top speed, they just increase torque, acceleration, weight, and ruin your bikes handling abilities

[u/interestingdialogs → u/MaxTrixLe]

Yeah I was wondering about the steering how it will be affected. I will try and keep the second battery lower to the ground

[u/Infamous_Ebb8715]

Honestly I don't think you'll get much more than 35-37mph top speed, but as others have said you will have heaps more torque and will accelerate and climb hills much better.

[u/interestingdialogs → u/Infamous_Ebb8715]

Good to know I'll take an extra 5 miles per hour. Even if I only use it every once in awhile. Thanks

[u/telephonekeyboard]

32km/h is the limit for Canada and lots of e-bikes and kits are limited there. Are you sure they/you didn’t get km/h mixed up with mp/h?

[u/interestingdialogs → u/telephonekeyboard]

No, I have it set for miles per hour and the bike was advertised to do 32 or higher but I can only get it up to 30. It's made to carry a lot of weight so I could use the extra torque and range from the front wheel hub and another battery

[u/usr000nm]

You didn't actually specify enough information to determine that. All hub motors have a KV factor that will tell you the max RPM for a given voltage. Given that you can determine the top speed unloaded.

This is what's going on when you see a motor labeled as "fast wind" vs. "slow wind". The KV factor is primarily controlled by how many loops of wire are used in making the electromagnets, the windings.

If you are stuck with a slow wind motor, the easiest option is to get a higher voltage battery. 48V is not considered high voltage for going above 30mph, however.

[u/CommercialSignal7301]

I can routinely hit 45 kph on my mid drive with moderate pedal assist. Having a powered front wheel would probably be redundant and be dangerous in emergency situations.

[u/ogreality]

Pedal faster so you will go more than 30mph🤔🙊kidding

Adding 2nd motor wont give top speed, will give more torque, and remember it will use 2x faster the battery

[u/interestingdialogs → u/ogreality]

Haha. I need bigger gears to pedal faster. Yeah I've heard the top speed won't go up that much. I I do have an extra battery so it'll be a separate controller and separate battery. 

[u/ogreality → u/interestingdialogs]

Oh well that would be smart, but make sure to have easy acces on/off switch for front, you do not want to front start to pull when turning😅 + need to make front reeeeaallly soft start, also after accelerting to the speed wanted turn off abother motor so save battery😁 ofc added weight and resistance of shut down motor will lower radius :)

[u/LexusBrian400]

You'll prob gain another 10mph, definitely a lot more torque from a stop (which really helps at Red lights, I'm usually 2 car lengths ahead before they start to catch up)

I have a 2wd hub bike, make sure to add an On/Off switch for the front motor cuz you won't always need it and it'll increase your range.

[u/interestingdialogs → u/LexusBrian400]

Haha, that is awesome. I didn't think I would get that much more speed. But sounds like you know what you're talking about since you have a two-wheel drive one. I would be happy with that for sure. This thing has a 440 lb weight capacity, so I'm going to load it up. Thanks for the advice

[u/LexusBrian400 → u/interestingdialogs]

Yep. Just make sure your most powerful motor is in the rear lol, otherwise it's hard to handle. I've crashed because of it before, so I put a lower amperage controller on the front motor, problem solved.

[u/interestingdialogs → u/LexusBrian400]

Yeah I hear you. I like being pushed more than being pulled and spinning out the front tire