Hello all, first time poster. My 11 year old daughter is going through treatments for brain cancer. We are trying to make her life as normal as possible during this time so she can enjoy being a kid. To that end, I'd like to electrify her trike so she can ride with us without getting exhausted. Her ride is a Catrike Dash recumbent tadpole (2 wheels in front) trike. It is a smallish and low to the ground with a 20" rear wheel. She weighs around 100 pounds and the trike is 29 pounds. I would like to make it possible for her to do 20-30 mile rides. Right now she could probably do 3 miles unassisted. I'm pretty handy but I just don't have much spare time to invest in a project. Is there a good kit or anything available to make this work? Thanks for any help you can give.
E assist for little girl with cancer
- Thread starter Xray
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John in CR
100 TW
She's gonna love it, and it will be great for you and your spouse too. Critical info we need for best guidance is what kind of top cruising speed do you want for her on flat ground, and what are the steepest hills you need to tackle. That trike doesn't have room for a mid-drive, which doesn't sound like you have time to design and install anyway, so what you want is a rear hub motor in a 20" wheel. Which motor and what voltage to run will be determined by the speed and hills answer for a properly tuned system. You can always up the voltage and give her go-kart performance later if desired. I would suggest a direct drive hubmotor so you can include regen braking in the mix, which greatly reduces brake maintenance and it a huge safety feature going down hills.
Do you have a budget in mind? You may even be able to get it covered by insurance as a mobility device.
Welcome to ES, you came to the right place.
John
Do you have a budget in mind? You may even be able to get it covered by insurance as a mobility device.
Welcome to ES, you came to the right place.
John
Ben Wilson
1 W
You can get all sorts of motors laced into a 20" wheel and they should fit fine on the back of a trike (I commute on a trike with E assist).
I'd suggest looking at the 20" magic pie (Golden motor), they do a 20" cast wheel with the controller mounted in the middle of the hub so there is a lot less wiring to worry about - with a 36v battery it should go well enough to keep her happy.
Have you got a rear rack on her trike? While it's not an ideal battery location, it should be fairly to mount the battery on the top of a rack.
I don't think you're going to be able to fit the 9 speed with the magic pie (a magic pie expert may correct me on this), so you'll need to change the shifter and grab a 7 speed. The lack of gears isn't going to hurt once the motor is part of the equation.
I'd suggest looking at the 20" magic pie (Golden motor), they do a 20" cast wheel with the controller mounted in the middle of the hub so there is a lot less wiring to worry about - with a 36v battery it should go well enough to keep her happy.
Have you got a rear rack on her trike? While it's not an ideal battery location, it should be fairly to mount the battery on the top of a rack.
I don't think you're going to be able to fit the 9 speed with the magic pie (a magic pie expert may correct me on this), so you'll need to change the shifter and grab a 7 speed. The lack of gears isn't going to hurt once the motor is part of the equation.
For a 150lb total weight and 20in wheel, she can get away with a much lighter GEARED motor.
I'd use a 350W MXUS or a small Bafang, maybe even Bafang BPM / MAC for more power than she can handle.
These motors are about 2-3.5kg lighter than the Magic Pie or other 500-1000W direct drive motors, and offer a freewheel for good pedal-only performance, while the DD motors would cog her speed down.
Once we know the maximum speed you need, we can give you solid advice where to buy ready made kits.
Most conversion kits come with a choice of thumb/twist throttle OR a so called PAS sensor - a primitive magnetic sensor that checks for the RPM of her pedaling and adjusts the motor power accordingly. However, since the cheap PAS sensors don't know the torque of her input, it's not as intuitive as it should be. Some riders have naturally high RPM so they get too much assist, and some low-frequency peddlers never get enough. There are more advanced torque sensors in the market, priced about the same as the motor itself, but most users over here prefer to use throttles to set the assist ratio seemlessly and independently of their pedal input. If you don't want her to get lazy, the intelligent torque sensor may get you interested.
I'd use a 350W MXUS or a small Bafang, maybe even Bafang BPM / MAC for more power than she can handle.
These motors are about 2-3.5kg lighter than the Magic Pie or other 500-1000W direct drive motors, and offer a freewheel for good pedal-only performance, while the DD motors would cog her speed down.
Once we know the maximum speed you need, we can give you solid advice where to buy ready made kits.
Most conversion kits come with a choice of thumb/twist throttle OR a so called PAS sensor - a primitive magnetic sensor that checks for the RPM of her pedaling and adjusts the motor power accordingly. However, since the cheap PAS sensors don't know the torque of her input, it's not as intuitive as it should be. Some riders have naturally high RPM so they get too much assist, and some low-frequency peddlers never get enough. There are more advanced torque sensors in the market, priced about the same as the motor itself, but most users over here prefer to use throttles to set the assist ratio seemlessly and independently of their pedal input. If you don't want her to get lazy, the intelligent torque sensor may get you interested.
dogman dan
1 PW
Assuming no crazy steep hills are involved, just about any "typical" ebike kit with a 20" wheel will do the trick. 20" wheels will give her a torque advantage, and 8-10% grades won't be a problem. No pedaling will be needed at all on typical hills.
You'll need a decent size battery to get longer range, the voltage of it depending on the speed you want to ride. Pingbattery.com is a very trustworthy source for safe and easy to use lifepo4. 36v 20 ah would give about 25-30 mile range at 20 mph max.
Where you are from affects which kit vendor we recomend, but the best ebike vendor in the world is Grin Cycles in Canada. Others vendors may be better if you live down under, or in europe.
You'll need a decent size battery to get longer range, the voltage of it depending on the speed you want to ride. Pingbattery.com is a very trustworthy source for safe and easy to use lifepo4. 36v 20 ah would give about 25-30 mile range at 20 mph max.
Where you are from affects which kit vendor we recomend, but the best ebike vendor in the world is Grin Cycles in Canada. Others vendors may be better if you live down under, or in europe.
NeilP
1 GW
I had to look up a picture, so I thought I would post one here for guys like me that had no idea what this bike looked like
chvidgov.bc.ca
10 kW
I've got a Catrike Road with a rear BPM 48V 500 watt kit from BMSBattery.com. I found the motor dropped right in to the rear with no spacing issues other than about a 1mm frame stretch, which was easy by hand. I use Ping batteries on it. I imagine the spacing is the same on the Dash, but you should measure it. It needs to be about 130-135 mm wide between the inner faces of the dropouts. You will need torque arms. If you use a Nine Continent motor from ebikes.ca you will need to file down the axle shoulders a bit to get it in there - I did that on my Actionbent trike. The NineC will be quieter and have a higher top speed. The Bafang will have better low end torque which is what you are looking for (I think), but isn't nearly as quiet as the the NineC. Grin is a great place to buy your 9C if you get one. I think a rear hub motor is by far the simplest solution. I would'nt worry too much about cogging on the NineC. Some cheap controllers have very little cogging with the NineC.
rscamp
1 kW
I would suggest something like the 20" wind eZee kit from ebikes.ca. This is a lighter geared motor as mentioned previously which can be purchased already laced into a nice 20" wheel. We have two of these powering our tadpole trikes.
chvidgov.bc.ca said:
Same experience here with the KU controllers from BMSBattery. But, I wouldn't put the heavy motor on that rig anyway.
To sum it up:
Geared: lighter, strong torque, bit louder than DD, better range in hilly areas.
DD: heavy, quieter, good torque, cogging when unpowered.
The choice really depends on the OP's priorities. Many will favour the DD because in smaller wheels it really performs well, but at the same time it introduces more cogging.
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