Printed Motor for short wheel base recumbent bike

[folkdancer]

I have a short wheelbase recumbent bike (not trike). 16" front wheel and 26" rear wheel, 21 speeds. Above seat steering. Lightning Thunderbolt by name.

A company called Cyclone makes an electric conversion kit using a motor on the chain with a tensioner to hold the chain down of the motor's sprocket.

Golden Motors shows something called printed motors which should work. I would have to build my own mount to hold the motor under the tube frame of the recumbent and a tensioner arm with sprocket. And I would need a free wheeling crank sprocket so I wouldn't have to keep pedaling if the motor was doing all the work.

Has anyone tried this? Any suggestions?

[Electrobent]

why not just a 16" front hub motor?

Get a cast one so you don't have to deal with short spokes.

I have a Turner T-lite with a 20" front wheel and I had a 500W 36V motor on the front and it was great.

I wore out the bearings until it got so wobbly that it shorted out and fried.

I ordered a 1000W 48V front motor to replace it and have yet to get it running . . .  (but that is my tale of woe here) 

[folkdancer]

I didn't know there were hub motors for 16" wheels. But also I am fascinated by those thin Printed Motors and would like to try one. If I could mount the motor under my seat it would be totally out of the way.

I may give up and get a rear or front hub motor kit.
Thank you for your suggestion.

[Electrobent]

I really like the front wheel being powered on my under seat steering (USS) short wheelbase recumbent.  I originally got into ebiking when I found myself too tired to get out of the way of traffic after a long ride.  You can't stand up to get more torque!
With the powered front wheel I could just point it and go to get started.  I am also very leery of subjecting that already over long and complicated chain to the pressures of a motor--if a chain that long broke under motor power it could do serious damage before you could stop it.

Golden Motor has a 16" Casted front wheel on their DIY Bike site.

My Turner T-Lite originally had a 16" front wheel but Milt Turner sold me a fork for a 20" wheel and it worked out fine (until my drop outs dropped out during testing of my 48V second wheel).  Maybe you could go bigger too?

The 20" is available with spokes but with the new deep rim that GM is using (for strength) there is not enough room between the rim and the hub for most airpumps or fittings.  The minimalist gas station fitting works best but that is no good on the road.

There is lots of torque though at small rim sizes!

[Bikemad]

Golden Motors shows something called printed motors which should work. I would have to build my own mount to hold the motor under the tube frame of the recumbent and a tensioner arm with sprocket. And I would need a free wheeling crank sprocket so I wouldn't have to keep pedaling if the motor was doing all the work.

If you used a printed motor, you would also need to install a gear reduction of around 12:1 between the printed motor and the rear wheel in order to run the motor at it's optimum rpm. This would also increase the torque by a factor of 12 at the same time.
With a 12:1 reduction, the PM48 would give around 310rpm at the wheel (at it's maximum power), which would give 24mph with a 26" wheel and a torque at the wheel of around 20Nm, and a forward force of around 60N (6.1Kg or 13.5lbs).

I would definitely go for a hub motor instead of a printed motor, as they will be much easier to fit.

Running on 48Volts, the 16" front wheel would give 33lbs of forward force, (25lbs force from the 26" rear HBS36R) and should have a top speed of around 25mph (just over 30mph for the 26" rear).



Please note that the 16" cast rim requires a wider tyre than normal, and I'm not sure if the cast rim is suitable for conventional V brakes.
Check this post for more details

If you decide to go for a rear hub motor, the Magic Pie would be a good choice with more torque than the smaller HBS36R motor, although it's slightly heavier, it has a built in speed controller and should be much simpler to fit.



If speed and torque are not essential, you could even consider the lightweight geared mini motor.



Alan
 

[Bikemad]

The 20" is available with spokes but with the new deep rim that GM is using (for strength) there is not enough room between the rim and the hub for most airpumps or fittings.  The minimalist gas station fitting works best but that is no good on the road.

Eric,

Perhaps you should keep one of these adapters in your tool kit:



Alan
 

[Electrobent]

Never seen one like that.

Where did you find it?

If this bike ever rolls again, I will need one of those but I still can't get Tom to pay me any attention.

[Bikemad]

Never seen one like that.

Where did you find it?

If this bike ever rolls again, I will need one of those but I still can't get Tom to pay me any attention.

I can't recall where that one came from but there's a similar one here but it's much more expensive than the UK ones.

You might be able to find it cheaper elsewhere, try Googling right angled valve adapter and see what you can find.

Alan