I have a friend who's in a wheelchair. She rang me last night to say she was hoping to buy a wheelchair / handbike attachment and fancied the power-assist version ... problem is, they're three and a half grand to buy.
Like this:
She's seen a wheel on ebay that has a self-contained motor within the hub and she thinks that she may be able to adapt it to fit her chair ... here's a link to the manufacturer: http://www.speedy.de/produkte/speedy-duo2/
Now, the problem here is that the hub she's seen doesn't come with a battery and she's been told a battery will be in the region of £700. I knew it wouldn't be cheap but that seems quite steep and they'd also want £200 for a charger.
She knows that it'll be a project that requires much thinking and metalworking which doesn't overly put her off, so my question really is will a suitable battery / charger really cost that much and has anyone got any better ideas because I know it won't be a straightforward project no matter how much I try to convince myself it will
The risk with bodging the battery side of things is cheap batteries are crap, and if you bodge it you risk it going wrong, best case is that it just fails. Worst case is fire or a big bang. I've seen videos of homemade electric bicycles doing this, the problem with a wheelchair is that the user can't exactly escape it quickly like a bicycle user would (i.e. drop and run)
Good quality li-ion batteries are pricey, though £900 for battery and charger seems a lot!
Something else ... I've just spotted that the cranks aren't set at 180 degrees but side by side. Can anyone think of a good reason for this, in my head it seems like it would be harder work and more like rowing than pedalling?
Bearbonesnorm wrote:Something else ... I've just spotted that the cranks aren't set at 180 degrees but side by side. Can anyone think of a good reason for this, in my head it seems like it would be harder work and more like rowing than pedalling?
Don't they work so you push one and pull the other at the same time?
From memory, there's a company in Glasgow called Kinetics who I believe build specialist bikes and kit for less able people, including electrically operated. Don't know how easy-going they are to discuss ideas with but may be worth making contact?
We go out into the hills to lose ourselves, not to get lost. You are only lost if you need to be somewhere else and if you really need to be somewhere else then you're probably in the wrong place to begin with.
From memory, there's a company in Glasgow called Kinetics who I believe build specialist bikes and kit for less able people, including electrically operated. Don't know how easy-going they are to discuss ideas with but may be worth making contact?
I'm pretty sure his name's Ben - he's on STW, seems a good chap.
There's a couple of chaps on there as well that have dabbled with the electrickery for powering bikes - might be useful to contact them. Try TJagain and (I think...) Trail Rat. Could be wrong on the 2nd one but I'm sure TJ has built one from a kit.
Re pedals I have seen this before and wondered why. Could it be a stability thing to eliminate a rocking motion depending on the disability of the person.?
Inline pedals would give a for and aft effect.
In the states they have a different approach to 'twist and go' so consequently you get bikes with stupid size motors doing high speed runs.
Not suggesting that you go down this route but the basic equipment, motors, controls, and chargers should be readily available.
Dont think you could ship an li-on battery though.
What sort of range is she hoping for ? That will drive the cost of the battery.
Second speaking to Ben@kinetics if your looking at a custom adaption for wheel chair I reckon he loves the challenge seeing some of the solutions he knocks out on his Facebook.
As for a motorised wheel off eBay. Not all motors in wheels are equal. Not all have the same mechanism of how they work. Direct drive motors are cheap but have lots of drag which makes it difficult to use as a normal vehicle Wen unassisted
Geared motors are much less draggy - barely noticeable infact apart from the weight mind.
I wouldn't have thought very much. Her thinking seems to be that after so many years using her hands to propel her chair they're starting to feel the strain. Using them in a different way is her solution.
The controller detects what needs to be supplied to he motor.
The battery does nothing more than supply power to the motor controller.
The battery is just a li ion battery with an on board BMS and needs to be pared to a charger
I have a Samsung 18650 celled 20ah battery in my cargo bike. Itt wasn't cheap but as above I didn't want to end up with recycled laptop cells of unknown origin going bang in my garage while charging.
I used e3emv for my stuff and imported direct also very helpful in identifying requirements.
Look also on the pedelecs.co.uk for used stuff and try endless-sphere for possible solutions they have all sorts of project threads on there for electric vehicles of all shapes and sizes from full size drag Cars to home built off road uplift attachments
Also pedals are together on a hand cycle to allow you to get your body weight behind it as it goes. It's actually really good exercise.
If the pedals were 180 out of phase you would not be able to get any weight behind it and would need to really gear down the vehicle to get it up hills etc - bit like you do in a recumbent - and most hand cycles are all ready inherently heavy by design due to obvious balance issues etc so.making it any harder would be a mare.
Ime riding a hand cycle has more in common with rowing
Trail-rat wrote:Also pedals are together on a hand cycle to allow you to get your body weight behind it as it goes. It's actually really good exercise.
If the pedals were 180 out of phase you would not be able to get any weight behind it and would need to really gear down the vehicle to get it up hills etc - bit like you do in a recumbent - and most hand cycles are all ready inherently heavy by design due to obvious balance issues etc so.making it any harder would be a mare.
Ime riding a hand cycle has more in common with rowing
Bearbonesnorm wrote:Something else ... I've just spotted that the cranks aren't set at 180 degrees but side by side. Can anyone think of a good reason for this, in my head it seems like it would be harder work and more like rowing than pedalling?
Given that the aim in both rowing and pedaling by hand is to turn a circle with your hands under pressure I'm guessing that the same reason (whatever that might be) that people row with both hands together as opposed to alternately is applicable in this case. Just randomly speculating though so may be way off.
If you pedals were 180 out of phase you would use your arm muscles alone. They are small
By them being in phase you use your power house to drive the bike forward.
Much like the reason why most folk get back cramps in MTB before the legs fail. Your backs your power house. As much as you think it's your leg muscles that make a conventional bike move forward. It's your back and core that will fatigue first.
