Friction drive on small kick style scoot?

[NeilP]

I was after a small folding e-bike, to stow in an aircraft locker, and a scooter was suggested. something I had not considered before

I looked at the price of the real nice ones, but the price is totally Ott for my needs.
I looked at the Razor E300 which is great, but it got me thinking about the problem and what i need. I then found this sub forum that i had never peeked into before, and a whole new world has opened up to me

Anyone ever done anything like the Kepler friction drive to clip on to those very basic small and light push along scooters, something that just drives the rear wheel direct?
This would be for fair weather hard road surface use only, so motor getting wet will not be an issue

Anyone got any pointers/ suggestions on how to do this

Just total off the cuff figures, but I imagine one fo those wheels is about 10cm diameter..so my quick calc just now, puts that at about 1500 rpm for 18 or so mph for the rear wheel

What sort of speeds do these RC style motors that keeper uses for his friction drive spin at?
Is this idea at all feasible?

[spinningmagnets]

One of the odd characteristics of the friction-drives is that they will run a bike at the same exact top speed, regardless of the tire diameter. It sounds strange, but its true. I seem to remember that the 63mm / 200-kV had a skirt bearing (recommended) and ran around 20-MPH / 32-kph on 5S LiPo. Any idea yet which style you prefer?



http://the.gasscooter.co/gas-scooters/x-treme-xg-550-gas-scooter.html

[NeilP]

One of the odd characteristics of the friction-drives is that they will run a bike at the same exact top speed, regardless of the tire diameter. It sounds strange, but its true.

That is probably a power thing, a motor spinning at the same rpm against a small diameter wheel has to go at a lower speed than the same motor spinning against a larger diameter wheel. So I suppose a larger wheel , needs more power to spin it, and the motor bogs down

Any idea yet which style you prefer?

Small light and folding..that will fit inside here:


Thinking of one of the small hard wheeled types. It is just for when I get a few hrs waiting for passengers at a foreign airport, and want to zip out a little way from the airport. Not for major sorties anywhere.

[Kin]

What you were describing, I think this has been done once or twice, but I can't remember where. There have also been projects like the Straight Razer, http://www.evalbum.com/4020, which could be further downsized.

Downside is that whatever you do you would probably want to use LiPo, probably, but because you're dealing with flight I think you want the LiPo *really* well protected. Unless, maybe you can get your hands on 2.3ah a123 or small headway (sidenote: You might not need a BMS for the a123...I know that on a lot of projects by the guy I linked, he just uses balance wires and balances every rare blue moon).

In picking the scooter you get I think there are a couple tricky problems. The lighter alluminum ones are great, but tend to have very little clearance to stick lipo under the deck so maybe you would have to either somehow extent the wheels or make a false deck above the deck, to fit the batteries. If you keep your range desires low I guess that makes this more feasible.

The scooters designed for E-vehicles (like the electric razor series) have tons of space (they're made for SLA), but they are usually made of super clunky welded steel. Definitively not cool.


If you work on this, please document at least a little about it ^_^. I'm a bit curious how it goes.

P.s, the constant top speed no matter diameter of wheel makes sense because your motor is spinning a wheel (or it's drum) as some rotational velocity. That, times the radius of the friction driver, is exactly how fast you're going. The wheel size is not doing any reduction or gearing at all.

[NeilP]

Oh yes, definitely going LiPo. Since I have some here, I was thinking of 5Ah or 10 Ah of 10s..So that is one or two sticks of 10 s NanoTech that I have.

They could even strap to the steerign column/stick handlebars..or as you say make a false deck to keep the weight low.

Now you explain about the top speed it makes total sense. Dependent on diameter of motor and its rpm, solely, the ground wheel just acting as the transfer of drive to the ground...Alternative would be to make a small hub motor, fit a tyre on a motor. Wonder what the smallest hub motor I can get is? fit a solid tyre to it

[Kin]

The guy I linked has made ~500watt hub motors for the tiniest 5" al scooters. It would be a pretty involved project (beyond my resources/skills) but it's also rather sweet. http://www.evalbum.com/1496. His webpage is where the details are.

If you're running 10s on a friction drive, it'll be a little tricky finding suitably low Kv motors.


With the direct drive system, the RC motors are being treated quite similarly to hub motors. The difference as I see it is that a 4" diameter RC motor can be attached to a 8" wheel and you'll be treating the motor as if it was an 4" motor, but getting the reaction at the surface as if it was an 8" motor. You'll also have slight better cooling.

[NeilP]

Nice, but a bit beyond my capabilities and equipment too

[melodious]

does it have to be electric? A 2stroke folding scooter would work as well. Only problem is the noise, (ahem) pollution level. There's even a micro 4stroke that could work which are far more quiet than the 2stroke and far more fuel efficient at about 150-200+ MPG.

http://robinamerica.com/series.aspx?sid=21

Just need to find the right shaft position (horizontal) and engine mount (4bolt)

http://www.davesmotors.com/s.nl/c.88503 ... id.2517/.f

Any craigslist in your area will have a daily assortment of people selling old scooters. Get one cheap ($25-50) with a bad motor, and swap out.

Is a gasser in that compartment not advisable? I don't want to endanger you.

[NeilP]

I could run it on avgas i suppose..I carry 480 kilo of that in the fuel tanks, but I am pretty sure they are not legal on UK roads/pavements.. The electric versions are more discrete.


Plus putting it away when it is hot having to drain the tanks etc before stowage..just a bit to risky. We do carry bit of medial kit in the wing lockers too..nothing critical..stuff like stretcher parts, so could not really risk getting the smell of fuel on that sort of kit

[adrian_sm]

Friction drives prefer having a complient tire to give a decent surface area to transfer the power, otherwise the shear force is too much. So if you want to go a friction dirve you would be better off picking a scooter with pneumatic tires.

Or if you like the hard wheel types, how about something like this:
viewtopic.php?f=35&t=29136&start=45#p445106

[NeilP]

SOmethin gliek that would be just fine..What is the motor ?

[adrian_sm]

I think he lists it in the first post of the thread I linked above.

Or if you like the hard wheel types, how about something like this:
viewtopic.php?f=35&t=29136&start=45#p445106

[chvidgov.bc.ca]

In my opinion the best non-electric small folding kick scooter (around 9 pounds) is a XOOTR. http://www.xootr.com

I'm good for distances up to 5 miles with no problems. These are lightweight, and pretty indestructable and have very high quality bearings so they glide extremely efficiently. They fit nicely in a suitcase or shopping cart. Xootr sells replacement wheels as well but they last for hundreds of miles. They stop well with the handbrake. The deck seems to be just at the right height for efficient kicking. Easy to balance. Wheels are around 7 inches in diameter so they are safer than a Razor that has much smaller wheels.

I have the Xootr Venus model, and the Xootr Roma model, and I use them a lot in urban environments in a travel setting, as well as for island scootering from my kayak. Highly portable and made in the USA. They are fairly expensive, around 200 dollars, but are excellent quality.

Recommended.

[NeilP]

Well for now I have two options
I just bought a used on on eBay, un branded and cheap and also swapped an electric Solex for a little folding sit down style thing
So have to see what I can do with these two items for now
Friction drive is out so looks like chain or belt is the way to go on these small wheel units

[sk8norcal]

I recommend air tires,
much better ride,

here's one with hub drive,
www.mywayeurope.com/

[NeilP]

They are nice too, but again massive price tag. Looks like it is a build your own job

[sk8norcal]

might be possible to buy that hub motor...
http://www.goldenmotor.com/hubmotors/hubmotorIndex.html