Building a Trike for elderly father

austtam

10 µW
Joined
Nov 10, 2021
Messages
6
Location
San Francisco
I'm looking to purchase a basic folding tricycle and converting it to an ebike for my elderly father. I initially wanted to put a mid drive motor on it as it's what I'm familiar with. However, I've come to learn that most basic trikes are single drive so a mid-drive doesn't seem feasable. From what I've read, it looks like front hub motor is most common. I'd actually prefer the bike to be slow 8-12 mph max is fine, but have enough torque to climb San Francisco hills (9-20degrees). I'd like to keep the total cost under $700 if possible.

-Mid-drive motors are pretty straightforward in terms of motor to drivetrain interaction...I'm not sure how hub motors work. Would a single-speed bike be ok? or should I get a 3 or 7 speed?
-How powerful of a motor would the bike need to get up a 20 degree hill? He's a small guy, 120 lbs.

Any other advice would be greatly appreciated. Thanks in advance.
 
20 degrees is a 36.4% slope, steeper than any paved road. To put it in perspective, famously steep Lombard Street in San Francisco has a 27% grade in the switchbacked section. That's about 15 degrees. Anyone who'd send an elderly man onto that stretch on an e-trike is probably the beneficiary of a sizeable life insurance policy on the old guy.

Anyway, even 9 degrees (16% grade) is something to be avoided if possible on a trike. Trikes steer themselves strongly in the downhill direction, whatever that is.

Ebkekit offers a specifically configured, not-cheap front hub motor conversion for trikes. Leaf Bike will supply their 1000W and 1500W direct drive hub motors set up to give the top speed you request. But a trike with a front hub motor is limited in how steeply it can climb by its static weight distribution and the amount that it's weight shifts rearward as it tilts uphill.

When adding motor power to the rear wheels of a granny trike, it's very likely that the increased chain tension will cause axle or frame flex that results in the chain skipping over sprocket teeth. This places a hard limit on how much climbing torque you can use, and it's destructive to the components.

In my observation of San Francisco, most of the really steep grades can be circumvented unless you happen to live on one.
 
Chalo said:
20 degrees is a 36.4% slope, steeper than any paved road. To put it in perspective, famously steep Lombard Street in San Francisco has a 27% grade in the switchbacked section. That's about 15 degrees. Anyone who'd send an elderly man onto that stretch on an e-trike is probably the beneficiary of a sizeable life insurance policy on the old guy.

Anyway, even 9 degrees (16% grade) is something to be avoided if possible on a trike. Trikes steer themselves strongly in the downhill direction, whatever that is.

Ebkekit offers a specifically configured, not-cheap front hub motor conversion for trikes. Leaf Bike will supply their 1000W and 1500W direct drive hub motors set up to give the top speed you request. But a trike with a front hub motor is limited in how steeply it can climb by its static weight distribution and the amount that it's weight shifts rearward as it tilts uphill.

When adding motor power to the rear wheels of a granny trike, it's very likely that the increased chain tension will cause axle or frame flex that results in the chain skipping over sprocket teeth. This places a hard limit on how much climbing torque you can use, and it's destructive to the components.

In my observation of San Francisco, most of the really steep grades can be circumvented unless you happen to live on one.

Sorry, i meant 20% grade, not 20 degree. Most of the hills in the neighborhood are in the 8-12% range. That should be mellow enough for a front hub powered trike to power through?
 
Hills are short mostly, so the rider can rocket up the hills fairly quickly if they have sufficient power.
Hub motors are simple
 
austtam said:
Most of the hills in the neighborhood are in the 8-12% range. That should be mellow enough for a front hub powered trike to power through?

Probably, as long as it can maintain enough traction on the drive wheel. It would be a good idea to mount a hefty battery on a front rack to shift some weight to the front.
 
Comrade said:
Chalo said:
Anyway, even 9 degrees (16% grade) is something to be avoided if possible on a trike.

Tadpole or delta trike?

I don't think tadpoles have the same tendency to steer downhill as deltas, but I think an upright tadpole would be prone to overturning on steep downhills or side slopes. The more common recumbent tadpole is likely no more a problem on steep grades than it is on flat ground.

Recumbent trikes are a poor choice for elderly riders, though, because it's difficult to get in and out of them.
 
Chalo said:
Recumbent trikes are a poor choice for elderly riders, though, because it's difficult to get in and out of them.

That's a strange. Every time I walked into a specialized recumbent trike shop, average age of customers was around 70. :lol:
 
Comrade said:
Chalo said:
Recumbent trikes are a poor choice for elderly riders, though, because it's difficult to get in and out of them.

That's a strange. Every time I walked into a specialized recumbent trike shop, average age of customers was around 70. :lol:

They're good for old folks who can only slither.
 
If you build, you want the trike kit from E-Bikekit. Its motor is a slow wind, specifically chosen to pull heavy trikes, but not dangerously fast.

If you can afford it,,, what you really want is called the Liberty Trike. FWIW, lots of e trikes cost quite a bit more.


Sold by the same guy, Jason Kraft. I used to work for them on line. The liberty trike is a folding trike that actually breaks in two for carrying it in hatchbacks or larger car trunks. Its the ideal vehicle half way between a house scooter, and a big trike. Smaller wheels give it incredible hill ability, and wider tires make it good on surfaces like gravel or turf at a festival, park, or not so much handicap accessible places. Its small enough that most stores let them inside with no hassles, if he needs mobility inside a store, and rode there. So it don't get stolen with your ass on it.

https://www.libertytrike.com/
 
EBR has a rather good review on YouTube for the Liberty Trike:
https://youtu.be/2JQMGppY94U

16 inch wheels, 10-12 MPH max speed, 36 Volt 500 watt front DD hub ....
They do fail to cover breaking it down or folding it up.
By the way ... the current model battery (8 Ahr) is sized so that it is legal to transport on an airline.
 
dogman dan said:
If you build, you want the trike kit from E-Bikekit. Its motor is a slow wind, specifically chosen to pull heavy trikes, but not dangerously fast.

If you can afford it,,, what you really want is called the Liberty Trike. FWIW, lots of e trikes cost quite a bit more.


Sold by the same guy, Jason Kraft. I used to work for them on line. The liberty trike is a folding trike that actually breaks in two for carrying it in hatchbacks or larger car trunks. Its the ideal vehicle half way between a house scooter, and a big trike. Smaller wheels give it incredible hill ability, and wider tires make it good on surfaces like gravel or turf at a festival, park, or not so much handicap accessible places. Its small enough that most stores let them inside with no hassles, if he needs mobility inside a store, and rode there. So it don't get stolen with your ass on it.

https://www.libertytrike.com/

This does appear to be the perfect solution and checks everything on my list. Thanks for this.
 
Glad this may help. I try not to spam the forum with selling my former employers stuff. But your specific needs sounded like the liberty trike would be very close to your needs. Jason got it priced very competitive to other full size trikes, which he sells as well. Deltas and tadpoles. It was about two years of development and prototyping to get to the final product. The fold or break apart hinge is the key. And the tiny, fat tire wheels make all the difference on turf or gravel.

Breaking it in half to transport is easy, but putting it back together is not a thing that is super easy for somebody who is physically deteriorating. Its about 35 pounds each half. So its best if there are two people to put it back together if the rider is not strong anymore. Practice makes it easier. A block of wood to hold the back half level helps for sure. Then you align the front to the back to slip in the pin.

Once in half, you need to be able to lift 35 pounds into a hatchback or trunk. In one piece, it will easily roll up a ramp into a van. Or it can be rolled onto a rear cargo tray that is 5' long. Just needs a bit more length than regular scooter carriers.

Its ideal for taking your mom or dad to a place where the house scooter works poorly, or its just a too long walk on rough gravel from the parking lot to the soccer game field. It will easily do the dirt or gravel path to the birdwatching place, fishing place, etc. Ideal for stuff like that, and Ideal for stuff like riding a mile or two to a dollar store to pick up milk or bread. The rear end is narrower than full size delta trikes, so it goes into your house door pretty easy, as well as store aisles.
 
The Liberty trike looks good.
Trikes can be tall, heavy and very tippy in turns.
The front wheel drive is a very big help as it has smaller tires, lower CG
I had big trouble with the rear drive iZIP .
https://endless-sphere.com/forums/viewtopic.php?f=3&t=87256
to fit thru doors it did things that made handling tougher. Tall narrow with only one rear wheel powered
Weighed almost 100lbs, and folding requires strengthening and that adds weight.
Low speed is essential for control, and knowing where and it will be used important
as these things can have limited flexibility. and vulnerable cargo.
I found mine closer to an electric wheelchair than to a bike.
Try riding one to get a feel for your proposed use.
I love recumbent trikes, but you have to almost do a somersault to get in and out of them.
 
Yep. its narrower than most delta trikes, so it can tip easier. One of the reasons its speed is limited so slow. But not a limiter that cuts power. Its just a slow wind, in a tiny wheel. So you get a ton of grunt up a hill if you need it.

Coasting down a hill way too fast is still possible, so riders do have to be careful on the downhills. And you have the same trike trouble with any steeply sloped road shoulders.

The main difference between the LT and a power chair, is that a reasonably fit, 100 pound person can take it apart, and put it in nearly any car. So you can take gramps out, without having to have him own a wheelchair van, or a special carrier on the hitch. You can take your car on outings. And gramps can live without a car at all, and still take himself to places closer to home.

Jason didn't invent the adult trike, but he solved the biggest problem with owning one. It would be difficult to take one on the bus, but if the driver is copacetic, possible.
 
Take a ride out to Alameda and visit with Zach Kaplan.
Zach is a top quality (not quantity!) rated trike dealer in the nation across the Recumbent community and has quite a few similar customers in the area.

I would recommend a Delta for ease of sitting in the seat. As long as the rider has some sense of cogency they should be able to ride it safely. And thats where Zach comes in. Safety will be the primary consideration. If he's going UP hills that steep, he'll be going down them too.

http://zachkaplancycles.com/
 
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