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Advice and Build Help for Single Wheel Electric Bike

09/27/2015 8:11 PM

i am building a single wheel electric bike, i am currently looking for a motor that has enough torque and rpm to run this bike, it has (at the apex of the wheel) 9' diameter, and will weight, with driver, i estimate about 550 lbs. i have come into another problem as well the ability to brake, any advise would be acceptable.

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#1

Re: advice and build help

09/27/2015 8:26 PM

What type and how many batteries are you using (and so what voltage will the motor need to be)?

Got an idea of speed and range?

What sort of terrain gradient (how steep are the local hills/roads?)

What's your budget?

Standard bike brakes should work, like any motor. What are your concerns here? You can wire the brakes if necessary to disconnect whatever electronic throttle control you plan on using.

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#4
In reply to #1

Re: advice and build help

09/27/2015 9:08 PM

Not sure I'm with you here.

A 9' diameter wheel carrying 550# will difficult to get moving with "any motor" and impossible to stop with bike brakes.

OP has not given this much thought.

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#12
In reply to #4

Re: advice and build help

09/27/2015 11:36 PM

Sorry, meant motor bike brakes.

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#7
In reply to #1

Re: advice and build help

09/27/2015 9:39 PM

i just when over my own notes and i have no clue how many batteries it would take, I'm still in the beginning stages. the terrain is rather flat and the hill grade i do not know. the speed and distance would be about thirteen miles with an aproximate milage of 35mph. i havent diagramed the circutry or alot of the gearing, the driver would be sitting in the wheel, ive seen several of these in scifi, fantasy anime and movies. i just wish to bring a working version into reality, as is i still have quite a bit to learn for i am only 18

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#24
In reply to #7

Re: advice and build help

09/29/2015 3:37 AM

Since you are only eighteen, and this is only a 'pipe-dream' that you only want to wish into existence, with the possible help of perfect strangers, let me help....

1. Roller blading will be a lot easier..in concept and cost.

2. 35mph is never going to happen. Set your sights on 5mph and settle for 3mph.

3. I doesn't hurt much if you fall off under these conditions: 3 mph; weight = 140lbs;

helmet =YES and tarmac = Yes. Knee guards and butt-pads can only improve matters. (send us a selfie)

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#2

Re: advice and build help

09/27/2015 8:28 PM

A "bike" has two wheels.

With no real information, further advice would be useless.

Will your motor be direct drive or use a reduction drive.

You have to give the forum something to work with.

Have you tried a search? Google has tons of "bike" forums.

I'd do a search for help there, first.

Electric unicycles are not an easy build, even if you have some idea of what you are doing.

I suppose you could call your contraption a "unike".

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#3

Re: advice and build help

09/27/2015 8:55 PM

tell the rider to diet

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#6
In reply to #3

Re: advice and build help

09/27/2015 9:29 PM

the rider would be my self and i only weigh bout 140

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#5

Re: advice and build help

09/27/2015 9:27 PM

That's not the main problem with a monocycle......since the riders weight is the driving factor, and stopping I might add, these vehicles are always limited in acceleration and specially stopping from any speed, by the rolling kinetic force of the operator vs the weight of the occupant....what you need is a gyroscopic force to offset the imbalance....a weight multiplier of sorts...

http://www.monovelo.com/

A cautionary tale...

https://www.youtube.com/watch?v=cM3fVXsPyUE

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#8
In reply to #5

Re: advice and build help

09/27/2015 9:41 PM

what would i use for a gyroscopic balancer ?

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#11
In reply to #8

Re: advice and build help

09/27/2015 11:29 PM

A spinning wheel...

http://www.gyroscopes.org/behaviour.asp

https://www.youtube.com/watch?v=gQY1Il_JYa0

http://www.gizmag.com/self-balancing-ryno-electric-microcycle-release/30832/

http://www.gyroscopes.org/how.asp

You might need 3 or more gyro's to keep vertical stabilization and to provide stabilization force on frame...

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#19
In reply to #11

Re: advice and build help

09/28/2015 3:18 PM

From the bottom of the last link provided;

'....There might be a way to accelerate the rotational speed of the rim of a gyro by using a short duration tilting force on the axis. The force's duration would be for much less then the length of time that is required for the rim to rotate 90 degrees. When the rim has rotated 90 degrees from the time the tilting force was first applied, The tilting force would be purposely reversed. The direction that the rim is rotating and the direction the rim would have moved due to precession are now close to the same. The two motions might combine and result in an increase in the rotational speed of the rim. ....'

.

Anyone know whether this is indeed the case?

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#21
In reply to #19

Re: advice and build help

09/28/2015 10:37 PM

Well I have one of those power balls, basically a mounted gyro inside a ball....the exercise is for the wrist...so you hold the ball tightly and twist your wrist left and right in a kind of circular manner and the rotational speed of the gyro is increased and the resistance grows greater....you can get the rotational speed up to something like 30k...

https://www.youtube.com/watch?v=SP-ydJ4HIoA

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#26
In reply to #21

Re: advice and build help

09/29/2015 10:23 AM

I like these too. The method described in the link for increasing the speed is different, though.

For the power balls, speed is increasing using friction to turn the very small diameter end of the spindle. The previous link you provided describes tilting and then reversing the tilt in the time it takes to make 1/4 revolution....which at 30k rpm would be a period of 1/2000 of a second. I'm fast, and my hand is well calibrated...for a human, but that is out of my range. ....but, perhaps you wrist gets more exercise than mine.

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#27
In reply to #26

Re: advice and build help

09/29/2015 1:06 PM

Well there is likely a harmonic associated with the speed of rotation...Don't ya think...

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#29
In reply to #27

Re: advice and build help

09/29/2015 5:24 PM

Sure.... provided some imbalance exists, which will be the case pretty much always.

....and it seems reasonable that you could increase the speed utilizing an imbalance by tilting and reversing the tilt at the right times.

.

I wasn't considering an imbalance. It wasn't mentioned in the link. It does make sense though. I just wonder if that is what the author had mind, or something that doesn't require an imbalance to work.

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#33
In reply to #26

Re: advice and build help

10/02/2015 4:47 AM

which at 30k rpm would be a period of 1/2000 of a second. I'm fast, and my hand is well calibrated...for a human, but that is out of my range. ....but, perhaps you wrist gets more exercise than mine.
!!!

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#9

Re: Advice and Build Help for Single Wheel Electric Bike

09/27/2015 10:07 PM

Good luck.

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#10
In reply to #9

Re: Advice and Build Help for Single Wheel Electric Bike

09/27/2015 10:30 PM

This trike has a 1000w hub motor with a 2kw lithium battery bank with a range of 60 miles@25mph. It weigh about 150lb and I needed disc brakes to stop it.

You will need much more then 1000w motor to drive that bike.

Tom

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#14
In reply to #10

Re: Advice and Build Help for Single Wheel Electric Bike

09/28/2015 3:09 AM

The person who wrote this does not know the difference between POWER in kW and es ENERGY which is in kWh. A battery stores ENERGY not power!

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#18
In reply to #14

Re: Advice and Build Help for Single Wheel Electric Bike

09/28/2015 9:41 AM

They deal in magic, not reality.

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#22
In reply to #14

Re: Advice and Build Help for Single Wheel Electric Bike

09/28/2015 10:39 PM

yes a battery stores energy stacking batteries will not only give you a higher voltage but also a higher amperage wich is what you need, you can have a low voltage at a high amp wich would deplete the voltage rather quickly or a high voltage and a low amperage wich would store more energy if i were to try and use kilowatts i would like ly kill my self for a car battery or litium battery do not run on kilowatts and as well will not run an electric mottor properly. killo watts is used for caculating constant incoming high voltage alternating current. and i sppologise for anny spelling and gramatical errors i am tired

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#32
In reply to #22

Re: Advice and Build Help for Single Wheel Electric Bike

09/30/2015 12:06 PM

What?

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#15
In reply to #10

Re: Advice and Build Help for Single Wheel Electric Bike

09/28/2015 3:29 AM

I still believe that throughput trip efficiency could be significantly improved through power averaging and regenerative braking.

Is it possible that torque per unit ampere could be increased by moving the point of impulse to the rim of the wheel?

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#13

Re: Advice and Build Help for Single Wheel Electric Bike

09/28/2015 1:44 AM

To improve the ability to brake, without roll over, center of gravity should be as low as possible. All that battery weight can be put to good use since battery positioning is typically pretty flexible.

Mounting batteries as low as possible on either side of the wheel (so as not to be limited by the tire/whel profile) will help.

Also making your own seating as low as possible is also important. Unless you are comfortable counter balancing your own weight with batteries on the other side, the profile on the tire/rim will restrict how low you can position yourself, so in that perspective a lower profile tire/rim combination is advantageous.

One of the problems with positioning yourself as low as possible is it will make it more difficult for you to influence the lean of the wheel, both at a standstill and while moving. I presume leaning is how you plan to turn. The ability to intentionally cause the vehicle to turn effectively in a controlled fashion is one of those options that you really shouldn't do without.

.

I'm sure it has occurred to you, but it is worth mentioning nonetheless. The dangers to yourself and others of operating, at even 30mph, a home built vehicle of several hundred pounds and radically different design should not be underestimated.

.

There are lots of possibilities for resisting forward roll over to allow stronger braking. Gyroscope stabilization has already been mentioned. Causing the wheel to deform into an elongated shape to shift the contact patch forward is another possibility that could work but is complicated.

A system of weighted pendums might work, but it would not be easy to get it right and it is fraught with danger.

An option that could help significantly and is not technically overwhelming is a horizontal tail. If a large horizontal surface were mounted behind the wheel extending back for a distance, even as a fixed passive device it could provide aerodynamic resistance to forward roll over... so long as forward motion exceeded any tailwind. If the stabilizer was mounted to trail the wheel by a significant amount, even with a tailwind, it could help to prevent rapid forward rolling motion.

It would not be too difficult to make the stabilizer more helpful by actively controlling the pitch and using an air foil.

.

Perhaps even something like a tail rotor on a helicopter could be employed with a fan on a long trailing level arm that only turns when corrections are needed.

.

Along similar lines, slowing by deploying air brakes is an option that can avoid problems of forward roll over and could even counter act if designed well.

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#16

Re: Advice and Build Help for Single Wheel Electric Bike

09/28/2015 6:25 AM

Is this what you have in mind?

http://mashable.com/2015/03/22/monowheel/

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#17
In reply to #16

Re: Advice and Build Help for Single Wheel Electric Bike

09/28/2015 9:07 AM

If that's what he's talking about and the wheel is only 9", his 140 pound body must be made out of neutron star.

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#20
In reply to #17

Re: Advice and Build Help for Single Wheel Electric Bike

09/28/2015 3:51 PM

The OP lists 9'....so 9 feet.

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#28
In reply to #20

Re: Advice and Build Help for Single Wheel Electric Bike

09/29/2015 1:47 PM

Yep, I missed that.

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#30
In reply to #28

Re: Advice and Build Help for Single Wheel Electric Bike

09/29/2015 8:25 PM

Completely understandable. Most people reading 'bike' are going to guess '9 inches' instead of '9 feet' most of the time. How often do you see a 9 foot wheel on a bike?

I think for efficiency sake, we make a lot of assumptions when casually reading.

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#31
In reply to #30

Re: Advice and Build Help for Single Wheel Electric Bike

09/30/2015 9:31 AM

This is what I thought of when I first read it as the OP used the word "bike" which automatically means two wheels to me. I was picturing this with a 9 foot main wheel, electrified and the EPIC faceplant that would most certainly be the end result of such folly.

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#23
In reply to #17

Re: Advice and Build Help for Single Wheel Electric Bike

09/28/2015 10:52 PM
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#34
In reply to #16

Re: Advice and Build Help for Single Wheel Electric Bike

10/02/2015 4:57 AM

GA. Perhaps many readers did not 'see' the OP's vision

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#25

Re: Advice and Build Help for Single Wheel Electric Bike

09/29/2015 8:12 AM

If you are truly building a "single wheel electric bike", that would be called a unicycle. My experience with my wife's E-bike tells me you have a torque control problem. You want to be sure the motor starts out very slowly, or it will rotate the driver around. Slow build up of torque seems to be the opposite of what you want with a unicycle, as they become more stable when you get moving.

On the other hand, the wheel diameter sound s a bit large for a unicycle, so are you saying a single drive electric bicycle? If so, there are many of them out there already, and they weigh quite a bit less than 300 pounds. Where is all the weight coming from? My wife's E-bike is a fat pig and it weighs only 25% of your total weight.

Braking of cycles has been worked out for years as we have everything from 14 pound road bikes to 1000 pound motorcycles equipped with very good braking.

So what are you building? More data would be helpful.

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