MomentumUpstart

Ok, its sounding like hub motors will always have a narrow rpm window of efficiency and will not have even assistance over a wide range of rpm ie good for both light and heavy pedalling. Is that true?

Why isnt changing the rear hub motor to a higher rpm version (or increasing the volts) the same as changing the gearing on a bicycle with a crank drive motor? Currently as soon I start to pedal with some effort the power assistance reduces greatly and it feels like I put in heaps of effort but i gain no speed.

Thanks for the post. I am still to learn about the crank drive motor. The price of them here was what made me choose the rear hub motor. I was just looking for best value to commute 20 miles to work. The simplicity of the rear hub motor attracts me also. I also do mountain biking and I completely acknowledge that crank drive would be much be much better weight balance, not to mention braking the rear wheel with hub motor does bugger all due to its extra weight. The one thing I dont like about crank drive is the power going through the chain and gears. I struggle to keep a normal road bike changing gears properly (very lazy on maintenance). I ride a single speed for short distances under 12 miles. I currently leave the ebike in the hardest gear possible and was thinking about shortening the chain and skipping the derailleur to stop the chain bouncing around and add some efficency. It sounds like the crank drive is much better for someone that wants to pedal hard with the added power. Is there anyway to get that same experience in a rear hub? Would the highest possible noload rpm on a 500W rear hub motor do the trick? I can change the gears to harder ones too to allow me to keep assisting at higher speeds.

Thanks, in your scenario with plenty of amps then extra gearing helps get more speed. But i think in my case I am limited by amps so lower gearing wont help me. I changed from 26x2.5 tyres to 26x1.1 tyres and Im still review stats to see if it was any faster. All I know for sure is that my arse was killing from the loss of shock absorption with the thinner tyres! I just bought a watt meter so will be interesting to see what amps it is running. This is a complete bike still with 1 year warranty so im thinking about starting another bike build if I want more speed, instead of stuffing up this one. Geeze it seems its all about the battery! Controllers and motors are pretty cheap in comparison. And without the right battery it doesnt matter what fancy motor and controller you have.

Thanks, that makes perfect sense now. Im finally learning something! What tyres are you running? If I did raise the current by adding some solder to the shunt or purchasing a 12 mosfet controller how can I read the amps? And are there any basic ways to see if the battery is not coping? I was thinking run it for a short time and measure the volts to see if it has dropped excessively

It would be awesome if I could run a constant 20A and have no increases for hills or extra load, is this possible?

Thanks, so bms current is what the battery can apply constantly and it can apply more for short periods of time for a hill etc? I would be happy with 24mph and am not very keen on buying another battery yet as it is a custom size to fit the inside of the bottom tube. From Alan Quays post above it seems like I could get close to 24mph with more amps. I was also thinking about replacing the motor with a higher rpm version to give me more top end speed and I would like to pedal a bit more. However I am concerned that the rpm is not currently the limiting factor as it can't hold a consistent speed near to the nolimit speed anyway. Hmmm

What do you think about a KU93 controller to bump up the current to 22A?

Im confused if yours is 270rpm and mines supposed to be 300/310rpm and my noload speed is 24mph. Shouldnt yours have a lower noload speed? I didnt think it was possible to go over the noload rpm/speed. Is it correct that more current will help increase speed as close as possible to the noload speed? If the motor stops giving power underneath the noload speed does that mean that it is hitting the current limit on the controller? I would be happy with 24mph on the flat.

Thanks for the reply. Is yours code 10 and on 26" wheels? How can I tell how much current the battery can deliver? So to go above 24mph I would need to increase voltage which would require a new 48V battery.

Hi, I have the following setup on a 26" mountain bike that was put together by a local company here in Australia. It is marketed as an offroad bike as it has large downhill style front shocks and wide 2.5" knobby tyres. The only way they can sell a bike with over 250W is to say it is offroad only. However, I use mine for long distance commuting 20+ mile each way on very remote paths. I might see 2 other riders each day and am very respectful (although I can do the same speed on an unpowered bike just not for as long). Currently the bike does around 20-21mph when fully charged and drops its way down to around 18mph by the end of the 20 mile ride. The bike is quite torquey and gets up to that speed very quickly. Its noload rpm (by me lifting the rear wheel and accelerating) is around 23-24mph. I am fairly fit and love cycling to work each day, however any more than a light pedal and the motor stops assisting. Goal: increase top speed (path is very flat, smooth and straight) and allow the use of more pedal effort. I dont mind loosing torque as there is only a few hills and I am happy to pedal harder. Goal is to reduce travel time. Motor: BPM 36V500W 26 (10) 1409245426 Controller details: Rated Voltage: 36V Under voltage protection value: 31V Limit Current: 22A Nominal current: 11A Rated Power: 500W Wheel Diameter: 26” Drawing Number: LK559-3-2 Ideas?

Yeah I agree that a wider smooth tyre would provide more grip and be safer. Interesting to see they arent that much slower. So they are slower to get to the speed but they can hold on to the speed as well as thinner tyres? Comfort is secondary to speed for me. Lots of those articles keep saying "at normal speeds". What about at 24mph, are the wider (1.75") smooth tyres just as fast as (~1")?

Thanks for so much great info! I personally feel much safer and faster on thin smooth road bike tyres than wide knobby mountain bike tyres (on a smooth surface).

Reducing safety with thinner smooth tyres on smooth ashpalt compared to knobby mt bike tyres?? I may be new to ebikes but im not new to bicycles.

That news about code 10 made me happy in the pants!!! Anyway I can reduce the "back EMF from the motor"? Or bump up the amps?