rear wheel hub vs geared motor question

Hi

I have a opportunity to make my commute bike rear wheel ( currently a normal wheel ) to an electric hub motor but I'd like some advice on whether to go geared or non geared. The bike is ridden a total of 30 mins each day for commuting.

I have a non-geared motor on the front wheel, but I find if Im not using electricity it has a fair bit of drag which I dont like.

I was hoping a rear wheel hub motor ( the model I'm looking at is a "freewheel" type with a screw on cartridge/gear cluster ) might not have as much drag or is that not possible? I was hoping the rear wheel motor might run free with no electrical/magnetic drag when the power isnt applied so it can just coast, which would then extend my range.

ANy thoughts welcome....thanks.

You got it right, one of the main benefits of a geared motor is it has an internal freewheel that allows the motor to sit still while you coast. no motor drag coasting.

They are also lighter, and when loaded properly, climb hills well. They make a bit more noise than dd, especially at full gallop. So if you run 30 mph all the time, you might like the dd better still. Not that much noise at all below 20 mph though.

Dont buy the geared motor if you weigh 300 pounds, that gets into overloading them on hills, or dont tow trailers. Don't buy it if you really prize the quiet ride.

To make your DD motor seem like its freewheeling, just tickle the throttle a tiny bit. Then it will coast freely with very little drag. not much throttle, just a tiny tickle will do, without using up your battery. If you ride down a mountain, you will find that drag is your friend. A geared motor can end up using up your brakes faster, but only if you ride down mountains. Little hills you can just bomb them, and use the speed on the next rise, or coast out the flat.

Hi dogman dan,

Thanks for the extensive info, its very helpful.

The cunning plan is to actually take the bikes on a 60 mile round trip to a few wineries here soon, so I was a bit worried that it might be hard work without being able to coast along properly with constant magnetic drag....

So, I think a direct drive might be the go, as I'm about 220 pounds and I like top speed when I can get it. My current drive is through the front wheel only ( first attempt at a DIY e-bike ) but will chnage it to a rear wheel direct drive/hub motor as sometimes I can get wheel spin trying to get traction when crossing a busy road, which can be unwelcome....and a bit dangerous.

I also think I may need to up-rate my battery to a 20 Ah from its present 10 Ah for the longer trip.

In terms of controllers, do you have any suggestions for a good controller - I'd like to have a programmable one that handles multiple voltages ( 36,48,60 ) and is easy to propgram via laptop. I dont need to do regen braking.

Cheers,

Steve

I suggest that if you want a DD motor for the reasons stated, get a controller that will simulate freewheeling, by feeding the motor a little power when coasting or riding unassisted. The folks here can suggest one. Personally I would never use a DD motor unless it were overpowered enough to get me up the worst hills easily, and get me started from a stop on an uphill incline without having to strain my legs.

LeftieBiker said:

I suggest that if you want a DD motor for the reasons stated, get a controller that will simulate freewheeling, by feeding the motor a little power when coasting or riding unassisted.

Click to expand...

I have a DIY version, with a coasting button that I operate with my left thumb. It applies just enough voltage to the throttle signal wire to provide around 50W at normal riding speeds. If I don't pedal, the bike will eventually slow to a stop after maybe 50 to 100 yards, but when pedaling, it feels like pedaling a normal bike. I only use it when I'm navigating around pedestrians because I've gotten used to using the throttle to do the same thing. Took a while, since it takes very little movement to apply just the right amount of throttle, but now that I'm used to it, it's pretty easy.

Hi

Ok, cool...I like the idea of efectively a low speed cruise control signal.....I have to say that using a hand twist throttle can be challenging getting around pedestrians. I am of the opinion riding an e-bike around pedestrians like driving slow through a flock of sheep on the road....but to be fair, most pedestrians dont comprehend how quick an e-bike can move, so when you do open the tap they get a fright. Some of the lycra brigade also get a fright. I think of e-bike riding as flying Concorde ....low/idle speeds in built up areas...then once youre down range far enough, open the tap up.....

Any suggestions about controllers please? I'm starting to think they may be a bit of a commodity item unless youre racing...

This controller below is what I run currently....its a 3 KW all steel body and pretty tough from exerience....although you need to have VB6 runtime installed to program it. Maybe its a good enough controller.......any thoughts?

https://www.uumotor.com/24-60v-50a-programmable-bldc-motor-controller.html

A photo - bike controller / battery box. Its a 36V battery and has lots of padding around it. The box is a standard plastic electrical IP56 rated box with internal steel frame ( to stop box distorting ). Connectors are standard 3 pin microphone connector ( motor 3 phase power ) and 9 pin computer plug for control cabling. I fill the plugs with waterproof silicon which is electrically inert and also acts like a glue. It also allows the plugs to be a bit more robust.

Depends on if your commute is in the middle of a city or has hills to climb. Geared does better in acceleration and climbs.

go to your local ebike store and try both types out that'll give you an idea of some of the differences between the track driving gear motor. Go find the big hill and try it.

So here's a technical question of principle, relating to two objectives that came up here: cruise control, and electric freewheeling.

Is it possible that the same controller won't do a good job on both?

I have cruise control on my Infineon clone (and really like it, use it all the time.) With this controller, the throttle governs Voltage/Speed.

It's kind of the opposite of electric freewheeling, and I can't easily achieve this with my voltage/speed control. The obvious choice for a controller that will do this, is one where the throttle governs "torque", like the Grin PhaseRunner, am I right? (In fact, of course the PhaseRunner and BaseRunner do implement it.)

And wouldn't that controller, conversely, at least need a lot more smarts to implement cruise control?

I'm the wrong guy to ask about controllers, I have tended to just buy the cheapest one on e bay.

Love the idea of auto coast, or coasting button. I just learned to give the throttle a tiny twist. I don't have a lot of rolling hills terrain in my area. Some places yes, but mostly its flat road up the rio grande valley, or over the big ass mountain. Down that mountain, I wanted coasting drag. More coasting drag down a mountain is why I liked the low speed DD motors so much. Sometimes that drag is your friend, but that's when you live in the mountains.

donn said:

So here's a technical question of principle, relating to two objectives that came up here: cruise control, and electric freewheeling.

Is it possible that the same controller won't do a good job on both?

I have cruise control on my Infineon clone (and really like it, use it all the time.) With this controller, the throttle governs Voltage/Speed.

It's kind of the opposite of electric freewheeling, and I can't easily achieve this with my voltage/speed control. The obvious choice for a controller that will do this, is one where the throttle governs "torque", like the Grin PhaseRunner, am I right? (In fact, of course the PhaseRunner and BaseRunner do implement it.)

And wouldn't that controller, conversely, at least need a lot more smarts to implement cruise control?

Click to expand...

I dont think you can set up cruise control directly in the controller software for the base/phaserunner, but connect a Cycle Analyst and you can have both. You can setup the throttle mode as speed/power/amp and it manipulates the throttle input. Use speed mode in one of the presets, and enable auto cruise, and it should work. It wouldnt be impossible to implement in the controller, though. It "knows" the rpm of the motor.