Need a hub motor recommendation - 36h rear cassette, 135mm OLD, 36V, 250-350W, 328rpm for 16" wheel build

[jahknob]

Anyone got thoughts on the best option for a rear wheel cassette hub motor for a folding bike conversion (motor can't go on the front wheel)?
It's going to be a 16" wheel, so would need a high-rpm geared hub, already have a 36h rim, would like 250-350W and 36V, with a 9-pin connector exiting from the end of the axle. The more compact and light the hub is, the better - not going for grunt, just some help getting away at the lights and some gentle assistance around town.
135mm spacing absolute maximum - be great if the axle is threaded right up to the hub body with spacers, rather than a solid axle that's just had the threads cut as far as the OLD distance either side.. Being able to tweak the hub OLD down closer to 130mm would be helpful..
Thanks!

 

[saneagle]

Anyone got thoughts on the best option for a rear wheel cassette hub motor for a folding bike conversion (motor can't go on the front wheel)?
It's going to be a 16" wheel, so would need a high-rpm geared hub, already have a 36h rim, would like 250-350W and 36V, with a 9-pin connector exiting from the end of the axle. The more compact and light the hub is, the better - not going for grunt, just some help getting away at the lights and some gentle assistance around town.
135mm spacing absolute maximum - be great if the axle is threaded right up to the hub body with spacers, rather than a solid axle that's just had the threads cut as far as the OLD distance either side.. Being able to tweak the hub OLD down closer to 130mm would be helpful..
Thanks!

Most cassette motors go over 140mm by the time you're finished. Why not use a freewheel motor? You can get your narrow width by fitting a 5 or 6 speed freewheel, which will be fine on a bike like that.

 

[Sturmey]

Anyone got thoughts on the best option for a rear wheel cassette hub motor for a folding bike conversion (motor can't go on the front wheel)?
It's going to be a 16" wheel, so would need a high-rpm geared hub, already have a 36h rim, would like 250-350W and 36V, with a 9-pin connector exiting from the end of the axle. The more compact and light the hub is, the better - not going for grunt, just some help getting away at the lights and some gentle assistance around town.
135mm spacing absolute maximum - be great if the axle is threaded right up to the hub body with spacers, rather than a solid axle that's just had the threads cut as far as the OLD distance either side.. Being able to tweak the hub OLD down closer to 130mm would be helpful..
Thanks!

I think the 16 inch wheel needs a faster motor than the 328 rpm you specified in your title which is the norm for a 20 inch wheel e.g. 400rpm for 16 inch. I think the 328rpm rated at 36v if fitted to a 16 inch wheel would probably need to run at 48v or your bike will be slow.

 

[saneagle]

I think the 16 inch wheel needs a faster motor than the 328 rpm you specified in your title which is the norm for a 20 inch wheel. I think the 328rpm rated at 36v fitted to a 16 inch wheel would probably need to run at 48v or your bike will be slow.

328rpm gives about 15mph downhill. Normal riding would be about 13 mph before the power drops off. Therefore if you want to go everywhere at 15 mph, 48v would be better, but you'd need to turn down the current to about 12 amps, otherwise you might get too much torque or overload the motor. Forum member Cwah ran his Q100 at 48v and 20 amps, high wore the gears substantially in the relatively short time he had it.

 

[jahknob]

Thank you all for replies to date - I've got several bikes with 328rpm 36V 250/350W motors fitted to 16" wheels (one front, one rear - think the rear may be rated a bit higher than 350W..) and if I set them up to provide maximum assist, they'll do around 18mph on the flat. That's plenty for me - I tend to ride with the assist level dialled right down, just to get the acceleration from a standing start at traffic lights and enough assistance to get up hills without breaking into a sweat.
Sadly, I'm not technically-minded enough to do more than get a wheel built with a hub motor that will plug into the control/power system I already have. I wouldn't know how to adapt my 36V system to work with a 48V wheel..
As for the first reply, using a freewheel is a pretty good idea and I was toying with it, particularly as, when using a motor set-up around town, one gear is actually enough. But, as I prefer to keep my bike set-ups flexible, I would rather have a rear wheel configuration that can be switched to a normal wheel and that gives me lots of gear options should the need occur - so I'd like to be able to have 8/9/10 gears if at all possible..

 

[jahknob]

I have used a Q128C CST rear 36V hub (actually, this was 500W!) successfully and it was quick, but heavy. I tried to source a Q100C CST (lighter, but less powerful for sure) from the same supplier (BMSBattery), but the hub they sent me was flawed...
BMSBattery have refused to engage with replacing it, saying that it was beyond the guarantee period - but the issue is a manufacturing defect that I discovered only when I had the wheel built (hub was originally bought as a spare) - the flats on the axle were machined at a completely different angle on each side, so the wheel cannot fit into any normal bike's dropouts! The company won't even offer me a discount on a replacement - I can return it (at my cost!) for a free repair, if I pay shipping both ways (and fill out all the forms to send the hub back to China!)..

 

[jahknob]

So, if anyone has any other suggestions for a hub to try..? I have found these online:
These appear to be the same:

36V 250W Brushless Hub Motor For E-Bike Electric Bicycle Front/Rear Wheel Drive | eBay

Rated power(W): 250W. Integrate Speed sensor: Yes. Model 1 : 36v250w Rear rotary Freewheel Motor. Hall Sensor: Yes. Available Wheel Size: 20"-28". Model 2: 36v250w Rear cassette Freewheel Motor. Drive and Freewheel: 6-11s.

www.ebay.com

Front / Rear Wheel E-Bike Conversion Kit 36v 250W Motor Hub Electric Bike 300RPM | eBay

Rated Speed(Km/h): 300RPM. 20"-28" Front/Rear Wheel Ebike Conversion Kit 36V 250W Electric Bike Hub Motor. Rated Speed(Km/h)300RPM. Rated power(W): 250W. Reduction Ratio: 01:04.5. Cable Location: Shaft center right.

www.ebay.com

36V 250W Ebike Hub Motor Electric Bike Conversion Set Front/Rear Rotary Wheel US | eBay

36V 250W Ebike Hub Motor Electric Bike Conversion Set Front/Rear Rotary Wheel US. Condition is New. Shipped with USPS Ground Advantage.

www.ebay.com

Don't think this will work because the axle is too wide:

36V 48V 250W 350W 500W Electric Bike Brushless Gear Front Rear Hub Motor Wheel | eBay

36V250W 350W / 48V 350W 500W. Rated Speed(km/h). Drive and Freewheel. Integrate speed sensor. shaft center right. Salt fog test. V/Disc brake. Brake type.

www.ebay.com

This one is rated at 500W:

ebike 36V 500W Brushless gear Hub Motor for Front rear Threaded Cassette Wheel | eBay

Tyre: Brushless Geared DC hub motor. Cassette Rear motor. Freewheel Rear motor. Front motor. Rated Speed(km/h): 25-32. O.L.D(mm): 100mm Front/135-142mm rear. Integrate speed sensor: Yes. Weight: 2.6g Front/2.8kg Rear.

www.ebay.com

Any thoughts??

 

[saneagle]

Thank you all for replies to date - I've got several bikes with 328rpm 36V 250/350W motors fitted to 16" wheels (one front, one rear - think the rear may be rated a bit higher than 350W..) and if I set them up to provide maximum assist, they'll do around 18mph on the flat. That's plenty for me - I tend to ride with the assist level dialled right down, just to get the acceleration from a standing start at traffic lights and enough assistance to get up hills without breaking into a sweat.
Sadly, I'm not technically-minded enough to do more than get a wheel built with a hub motor that will plug into the control/power system I already have. I wouldn't know how to adapt my 36V system to work with a 48V wheel..
As for the first reply, using a freewheel is a pretty good idea and I was toying with it, particularly as, when using a motor set-up around town, one gear is actually enough. But, as I prefer to keep my bike set-ups flexible, I would rather have a rear wheel configuration that can be switched to a normal wheel and that gives me lots of gear options should the need occur - so I'd like to be able to have 8/9/10 gears if at all possible..

You don't need any special knowhow. A 48v controller and battery are the same as 36v ones. You just connect them together like the 36v system and everything works
The only difference is that the motor will spin 30% faster when you want it to, and you get 30% more torque.

 

[Sturmey]

...... but the issue is a manufacturing defect that I discovered only when I had the wheel built (hub was originally bought as a spare) - the flats on the axle were machined at a completely different angle on each side, so the wheel cannot fit into any normal bike's dropouts! .......

Interesting. I wonder is it possible that your motor is the type where the axle has two separate left and right section parts that are not correctly lined up, which might also explain the reason for the defect and also mean repair might be possible?

 

[harrys]

How about the Q100H freewheel or AKM100H. Both are available in 328 rpm, as I think they are either the same motor or one is a good copy.

The nice thing about the freewheel version is that they use two spacers and a nut under the freewheel to set the OLD. I had a 130mm alloy frame that I was afraid to spread, so I shortened one spacer and dropped down to narrower freewheel with less gears,

On 48V, the 328 winding will show 28 mph no load, but I've never had the bike above 18-20 mph as I run it on 36V. It is a little folder anyway.

I have spoked my motors myself. By the time I buy a quality rim and Sapim spokes, the cost is the same as getting a wheel shipped, but I know my parts are higher quality. I've also seen pics of chinese built 20" Q100H wheels with radial spoking on this forum. That's crazy, but maybe that's necessary with 12G spokes. I do a single cross pattern with 14G spokes (13G at the ends). It might be harder with 16" wheels.

 

[jahknob]

Interesting. I wonder is it possible that your motor is the type where the axle has two separate left and right section parts that are not correctly lined up, which might also explain the reason for the defect and also mean repair might be possible?

Maybe - but I am not sure that I could deal with whatever I find if I was able to open up the hub!!

 

[jahknob]

How about the Q100H freewheel or AKM100H. Both are available in 328 rpm, as I think they are either the same motor or one is a good copy.

The nice thing about the freewheel version is that they use two spacers and a nut under the freewheel to set the OLD. I had a 130mm alloy frame that I was afraid to spread, so I shortened one spacer and dropped down to narrower freewheel with less gears,

On 48V, the 328 winding will show 28 mph no load, but I've never had the bike above 18-20 mph as I run it on 36V. It is a little folder anyway.

I have spoked my motors myself. By the time I buy a quality rim and Sapim spokes, the cost is the same as getting a wheel shipped, but I know my parts are higher quality. I've also seen pics of chinese built 20" Q100H wheels with radial spoking on this forum. That's crazy, but maybe that's necessary with 12G spokes. I do a single cross pattern with 14G spokes (13G at the ends). It might be harder with 16" wheels.

You are quite right about the freewheel version - but I am so many years away from the last time I used a freewheel and I don't think that it would match up with the 9s shifters that I would like to use..

 

[Sturmey]

Maybe - but I am not sure that I could deal with whatever I find if I was able to open up the hub!!

I dont have any direct experience of hub motors with split axles. My first thought is perhaps the axle ends/flats would line up without dismantling by putting a 10mm or adjustable spanner at each end and turning. But on looking at the diagram, I think the motor needs to be partly dismantled, the 3 screws removed and axle can be turned in 120 degree steps as below.