Hello from the UK - unusual project on the go.

[Twelvebears]

Hi everyone.

Just wanted to introduce myself and say hello.

I live in Hertfordshire England and I’m a wheelchair user. My project is the progressive upgrading of the front mounted power drive I have for my wheelchair.

It’s basically a small bike front fork with a frame and brackets which attach to my chair. It uses ebike parts and a direct drive hub motor running at 48v

While it has been great fun and given me a lot of freedom without the use of my car, anyone who knows about mobility/disability equipment will know that everything cost a fortune. Yes the arguments about low volumes do have some bearing, but as I’m discovering, there is also a massive amount of profit made by selling otherwise unremarkable engineering as specialist equipment.

I’m not going to name the manufacturer involved, but to give just one example of questionable engineering, there is not connector between the hub motor and the controller, so as a friend discovered, you can’t actually detach the wheel and hub to say, change a tyre or the disc rotor, without cutting the phase cables.....

I should point out this piece of kit cost nearly £5k (that’s GBP) and yet the motor doesn’t even have Hall sensors, and is clearly using a very generic Chinese controller.

I’ve already added a second battery for additional range and a bit more weight over the front wheel for traction. The next Phase of improvements is to fit a Grin Phaserunner, v3 Cycle Analyst and sort out that wiring!

After that, replacement front fork with suspension is on the cards, probably with a different motor (either before or after I melt the current one).

I’m finding this whole area of ebikes fascinating, and this form seems like a great place to learn.

Looking forward to the journey!

 

[flat tire]

You'll probably have better luck just getting actual mobility parts from banggood or whatever.

 

[markz]

A single motor that pushes you thats on the rear, between the wheels.

https://i.ytimg.com/vi/h5HLAX1hfTM/hqdefault.jpg

A pusher motor

https://inventionaday.com/wp-content/uploads/2018/05/918sem-gRXL._SL1500_.jpg

Hire a fabricator to make either setup for you.
Leafbike sells small motor wheels.
https://www.leafbike.com/
Look under DIY Bike conversion on the left hand side.
Get a kids bike, for the fork and headset.... or perhaps better is a folding bicycle fork/headset because then you can have an extendable handlebar.

Another option, two hub motors in the wheels, then figure out how to merge each side with either their own separate controllers powering the mobility device or a single controller. Then how do you steer.

 

[amberwolf]

It’s basically a small bike front fork with a frame and brackets which attach to my chair. It uses ebike parts and a direct drive hub motor running at 48v

Sounds like the common DaVinci Mobility unit; we've seen them before here on ES. They work well for some; there's another recent thread where someone is working on theirs but I cna't find it right now. :/

I’m not going to name the manufacturer involved, but to give just one example of questionable engineering, there is not connector between the hub motor and the controller, so as a friend discovered, you can’t actually detach the wheel and hub to say, change a tyre or the disc rotor, without cutting the phase cables.....

Usually there's enough slack in the cable to be able to do this, though it may be tied down to the frame somewhere to keep it out of the way. If they didn't provide slack, or any other way to deal with those issues, then that would be pretty shortsighted.


While it's likely that they went the no-connector and sensorless route for cost reasons, there are other good reasons for them:

The benefit to no connectors is that connectors cause more problems on environmentally-exposed electrical stuff than any other problem. A simple poor connection on just one wire can totally immobilize it.

Sensorless is, while annoying in some cases where a controller can't start the motor moving (like uphill, etc.), more reliable than sensored. There are five less wires to break or short, and a minimum of seven less electronic components to fail (three hall sensors, three pullup resistors, and the MCU that reads them).

The next Phase of improvements is to fit a Grin Phaserunner, v3 Cycle Analyst and sort out that wiring!

The CA is very useful; it's even been used to help control a handcycle via torque/PAS control.

After that, replacement front fork with suspension is on the cards, probably with a different motor (either before or after I melt the current one).

If you need more weight on the front, a bigger DD hubmotor will give you more continuous power, but reduce your range, because the startup currents will be higher. But a geared hub like the MAC could give you at least as good a startup torque with less weight and less startup currents. Depends on what kind of speed and torque you are after (since you're probably "stuck" with the small wheel diameter?).

You can check out http://ebikes.ca/simulator and play with different motors, controllers, and batteries, with differnet wheel sizes, etc., to help you get an idea what setup may better do what you're after.

Does the chair itself have suspension? If not, and if you can change wheels, you could go for 29" (700c) fat tires to improve the ride at that end of the unit. You'd have to come with larger handrings (assuming your present wheels are 26") and a way to mount htem to the wheels. Perhaps also move the axle mounts up a couple inches so the seat isn't any higher off the ground,


(FWIW, I once was going to build an e-trike out of a wheelchair and the front end of a bike; I never ended up doing it but thought about it a fair bit in a thread I can't find now. Didn't know nearly as much as I do now; the SB Cruiser trike is much more useful (though really heavy), and the Raine Trike a better ride quality with the larger rear wheels than SBC.

 

[Sunder]

I did a short contract for a medical supplies manufacturer. The whole deal is a scam at our expense, but here's how it works:

US manufacturer makes some nice gear. They get it certified as medical/disability support equipment, which raises the price substantially.

AU importer discovers it during a junket. Asks doctor friends of theirs whether they would use it. If the answer is yes, they importer pays usually between 100k and $1m to have the device recertified for Australian use.

The importer then lobbies the doctors and hospitals to use it and recommend/prescribe it. Not making any accusations, but sometimes the line between entertainment, education and bribery is blurry.

Those at the top who know nothing about the equipment are persuaded to use it. They go out to tender to ensure they get the best price.

Guess what -only one importer can supply it, because nobody else has the certification. They could spend the $1m just to have a chance to bid, but tenders have really tight time frames.

The sole importer can then pretty much ask his price. I don't know if this is typical, but one example I saw, a medical imaging machine was bought for $800k and sold to hospitals for $3m. And every hospital needs one. Then on top, they get a service contract to keep spare parts and an engineer that can repair them.

If you have the contacts in the roght places, its money for jam.

 

[dogman dan]

Have to agree about the overpricing.

Because you still need a relatively low speed much of the time, I would say look for a low rpm, front hub, direct drive motor with halls, and a decent controller to run it. Ideally, in 20" wheel. If your fork is smaller, then replace the fork now.

The easy solution I know of, is a trike motor kit from E-Bikekit in the US. This kit has the low rpm motor, and the controller includes a reverse. It runs 36v or 48v. You can also buy just buy the motor only, and find a controller with reverse that runs 48v. 22 amps controller on that kit btw. I'd say the kit without motor would be a great start, because then you get a good setup that works out of the box, and plenty of power for your needs I bet.

https://www.ebikekit.com/collections/etrikekit-no-battery/products/e-trikekit-no-battery?variant=27959836614


If you really want grunt, then buy just the motor, and pair it with a 40 amps 48v controller. Top speed would be a bit high, at about 20 mph or perhaps more, but you'd have the stoke to burn tires up in a few weeks, if you hit it hard all the time.


I assume you cannot sit on a regular trike. But I'd if you can sit in regular chairs and hang on to handlebars, you might look into one of the trikes that EBK sells. Like take the chain and pedals off of this. And possibly put a different seat on it, that you can be belted into.
https://www.electrictrike.com/collections/recumbent-electric-tricycles/products/sun-seeker-eco-delta-electric-trike

 

[markz]

I see an old fella on a mobility scooter and he goes really fast, not sure what he did to his setup. I feel sad when I see another older fella, having a hard time walking his way. They get frustrated and they look for alternatives and they see a sky high price. People only get older, so they need mobility, not just a slide walker, or cane. I saw a genius setup someone had, it was a very minimalistic fold up, sit down mobility scooter that he easily folded up and put in his trunk.

 

[wturber]

I did a short contract for a medical supplies manufacturer. The whole deal is a scam at our expense, but here's how it works:
<snip>

I have a table tennis friend who plays in a wheelchair. He recently got one of those front drives that attaches to his chair and was showing it to me. I immediately recognized the KT-LCD5 display. So it wouldn't surprise me at all if these "specialty" devices aren't nearly as specialty as the purveyors would have folks believe.

OTOH, my friend absolutely loves the device and it works great. It may be this device:
https://www.amazon.com/Firefly-Electric-Attachable-Handcycle-Wheelchair/dp/B004WLMNTY

 

[markz]

Yeah the purveyors of "specialty" machines are $pin Doctor$, its all in the marketing!

That is why I linked to the Leafbike and/or Leafmotor kit because they have such small hub motors available.

Do a specialty front end so the rider can steer, place the battery under the seat cushion at the back part, and controller on the front part.

 

[dogman dan]

There is also a big market for something halfway between a mobility scooter, and a regular e bike. This is not good for wheelchair people, but ideal for those who have an indoor scooter that is not adequate for a trip to the soccer field to watch the grand kid play, a run to the store, or trip to the doctor 5-10 miles away. You see these people all the time, struggling to make that scooter do what they need, if they can't drive anymore.


Jason, at Ebikekit, redesigned the delta trike for this market. Made it smaller wheels, more compact, and as a folder, it breaks in two. Broken down, a reasonably fit relative can lift it into a hatchback car, or large trunk one piece at a time. Its main feature is a smaller front wheel, and wider tires for dirt paths or grass that stops an indoor mobility scooter. It turns tight enough for store aisles though. Its selling well, introduced a couple years ago under the brand Liberty Trike.


Some would call it overpriced, but not really for ready to ride, good quality e bikes with customer support. Way underpriced, compared to a wheel chair attachment.