D-I-Y Great Nick Andrews Trike(GNAT)

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I am the lucky owner of a GNAT folding trike suspension all round on its 20 inch wheels SRAM 7x3 rear hubx Shimano triple front chain gives 63 choices of gear.
16000 miles in 12 countries to date.
I am now rather decrepit(neuron disease+74 years.
I would like to D-I-Y an electric conversion.
My neighbour has 2 trikes and he suggests a crank motor.
All suggestions gratefully received.

 

[vfr400]

I am the lucky owner of a GNAT folding trike suspension all round on its 20 inch wheels SRAM 7x3 rear hubx Shimano triple front chain gives 63 choices of gear.
16000 miles in 12 countries to date.
I am now rather decrepit(neuron disease+74 years.
I would like to D-I-Y an electric conversion.
My neighbour has 2 trikes and he suggests a crank motor.
All suggestions gratefully received.

It might be an idea to show what it is!

 

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Here hopefully is a picture of Nicks later carbon fibre version.

Google Image Result for http://www.foldsoc.co.uk/cf2000/gnat.jpg

I will dig out a photo of my fibreglass version.
Nick generously lent me his moulds and I D-I-yed the rear middle and front boom from GRP

 

[vfr400]

Here hopefully is a picture of Nicks later carbon fibre version.

Google Image Result for http://www.foldsoc.co.uk/cf2000/gnat.jpg

I will dig out a photo of my fibreglass version.
Nick generously lent me his moulds and I D-I-yed the rear middle and front boom from GRP

If you're serious about needing help, you need to provide proper photos of your bike showing all the details of the wheels, frame, bottom bracket and gears.

 

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If you're serious about needing help, you need to provide proper photos of your bike showing all the details of the wheels, frame, bottom bracket and gears.

 

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Hope these will be useful.
I built several wheels for this machine plus assembled the bits put it together and maintain it so no problem building.
I fly RC electric aircraft so used to dealing with 700watt brushless motors/controllers/chargers/LiPo batteries.
Clueless about electrifying my trike.

 

[peter.c]

Please can you show a clearer picture of the bottom bracket and pedal area showing the width and depth of material etc
From what i can make out do not think a mid drive will fit ,looks like to much material around the bb so the motor might foul on the frame

 

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While the bottom bracket is a standard Shimano bottom bracket I can use pretty much any mid range price SPD pedal/triple chain ring set up-might change to a pedal drive that eliminates the front mech-which is always in the way on mount/dismount.
However I suspect a limiting factor is going to be there is almost nil protrusion of the bottom bracket from the front boom.
Its freezing and pitch black outside I will measure up and get a photo tomorrow.
I suspect I will have to build a 20 inch electric hub rear wheel.

 

[peter.c]

The lack of protrusion might be a good point the motor will just be at an angle, my concern is will it fit without catching the frame look forward to the pics

 

[vfr400]

You need a chain drive kit, which seem to be a bit thin on the ground these says. I found this one from Cyclone. Eclipse bikes are agents for Cyclone, so it might be worth talking to them.

Powerful DIY e-bike kit high speed Enduro electric bike 100km/h

 

[Fat Rat]

Hi welcome to the site

 

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You need a chain drive kit, which seem to be a bit thin on the ground these says. I found this one from Cyclone. Eclipse bikes are agents for Cyclone, so it might be worth talking to them.

Powerful DIY e-bike kit high speed Enduro electric bike 100km/h

Fascinating site giving me ballpark budget figures.
Looks like the Cyclone freewheel kit might build into my seat tub.
I hoped I could install a motor on the pedal drive but this would require hanging the motor on the not very stiff front drive boom way out in front.
Still got to look at rear wheel drives.
Might just build an electric trike

 

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Here are a few photos of the bottom bracket

 

[vfr400]

A bottom bracket motor will put about four times as much force through the crank compared to what you presently have. Are you sure the frame and fixing of the BB are strong enough?

 

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A bottom bracket motor will put about four times as much force through the crank compared to what you presently have. Are you sure the frame and fixing of the BB are strong enough?

Having put in thousands of miles on this recumbent on Dutch cobbles Berlin pedestrian cobbles the Crete mountain ranges etc I have confidence I can d-i-y a purpose built front boom in carbon fibre to house the motor.
Problem being putting 1HP through my chain which is 3 times longer than a conventional 2 wheeler is a concern.
Never had a chain problem with leg power.
As you can observe grp has long been struggling to cope with the forces generated by the bottom bracket.
At 74 years of age speed is not an issue.
Good point about the frame and fixings-this machine has topped 60 mph (downhill)
It has overtaken cars negotiating the bends down to Rothesay harbour (Canada hill-serpentine road) in days gone by
I am considering mounting the motor in the seat tub using a freewheel set up.
Is there a comparison of motors available?
Putting £500-£1000 into electrification I want brushless motor only.

 

[peter.c]

The mid drive will not work without serious modification to much material around the bb. The motor will foul and unless you cut a normal bb off a frame and bond it so its sticking out a secondary chain drive motor or rear hub is the way to go

 

[vfr400]

Having put in thousands of miles on this recumbent on Dutch cobbles Berlin pedestrian cobbles the Crete mountain ranges etc I have confidence I can d-i-y a purpose built front boom in carbon fibre to house the motor.
Problem being putting 1HP through my chain which is 3 times longer than a conventional 2 wheeler is a concern.
Never had a chain problem with leg power.
As you can observe grp has long been struggling to cope with the forces generated by the bottom bracket.
At 74 years of age speed is not an issue.
Good point about the frame and fixings-this machine has topped 60 mph (downhill)
It has overtaken cars negotiating the bends down to Rothesay harbour (Canada hill-serpentine road) in days gone by
I am considering mounting the motor in the seat tub using a freewheel set up.
Is there a comparison of motors available?
Putting £500-£1000 into electrification I want brushless motor only.

There's a whole range of motors you can use. One method is to use a hub-motor. Mount it on a couple of drop-outs (drop-ins) in the middle of the bike. If you use a rear one, you put a cassette or freewheel on it and use two of the gears: One with the chain to the crankset and the other going back to the derailleur, similar to the arrangement that the Cyclone kit had. The cassette on the hub-motor will give you some options for matching the ideal chain-speeds and getting the motor running at its most efficient speed. Whatever you do, you're going to need to do some fabrication work for brackets and things. The best location for the motor is in the middle of the vehicle and as low as possible - much better than a crank-drive stuck up the front.

whatever you do, the mounting has to be rigid or else the chain will keep jumping off.

 

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Many thanks for your practical suggestions.
The rear drop ins already use electric motor friction washers to combat the side forces genetrated by the tadpole set up.
The hub motor appeals since building a wheel and locating it will be an easy task-I take the point that the motor torque might require stronger mountings perhaps even a set of rear carbon forks.
In addition the hub motor will have no chain transmission drive issues?
Could a soft start controller not ameliorate some of the motor force?
Ideally I would prefer the motor and battery mounted near the CG ie in the tub under the seat.
Regarding the chain jumping off I built the original chain line with the front middle chain ring lined up with the Shimano 7 speed derailer on the middle cog via a skateboard ballraced wheel with groove width to match the chain-always worked failure free-now on its third set of 3 chains and second set of ballraces.
Presumably the Shimano derailer tensioner is sufficient to avoid motorised chain jump?
Building in support in the seat tub for the motor would be a straightforward job.

 

[vfr400]

I think you're misunderstanding me. I'm talking about using a hub-motor without spokes mounted in the middle of the bike to drive the chain, like this, but with a motor instead of a jackshaft:

 

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You are correct I completely misunderstood.
I thought you meant using a Cyclone mid motor type set up where the motor is already fitted with a drive cog (and free wheel?).
Ahh do you mean utilising the freewheel and 7-11 cassete derailer on the hub out to the rear wheel.