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Author Topic: Magnetic gears, for a bicycle. Chainless bike, dragless drivetrain  (Read 28685 times)

Cloxxki

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I don't believe the magnetic gears offer overunity. But that's not what my post is about.
 
All my life, I've been fed up with bicycle chain. They wear, get dirty, noisy, and break when least convenient. Oh, and they offer unwanted drag. Still, they are better than the alternative, V belts. Unless...
In progressive high-end bicycle design, the chain and chainline create more and more problems. I want to rid the world of those.
 
Enter, the chainless bicycle. And no, als not an cardan axle.
 
Imagine a bike tire or rim lined with evenly spaced directionally magnets. Say, one, two or three per spoke hole. I presume more narrow magnets will weight less and offer better traction.
Because, although magnet gears to my knowledge run 100% efficiently especially at bicycle rpm ranges, they do of course slip. Having the interaction at the very outer end of a bike may offer a distinct advantage over a typical bicle chain (cog roughly 1/10 the tire's diameter) should help. However at this stage I am not sure how it works out then the driven wheel is 73cm across, and the drive wheel is, say, 15cm. the drive wheel would need laterally place magnets perhaps, to account for side-to-side wheel flex (it a reality of life, and in fact aids rideability of the bike). The wide drive magnets might be curved around the receiving wheel magnets to add interaction? My agnetic knowledge already runs out here. Also, I can see a second or third drivewheel be added on the bike frame to increase slip-thorugh torque.
 
But imagine it for a second.
The rear wheel would be the same as the front wheel, except for the magnets on the outer diameter.  If you go crazy, some pedal power could be tapped off with a pickup coil and be transferred to the front wheel, either via more magnetic gears, or a hub motor. I am not proposing a full-on electric motor conversion becaue I suspect greater loss of efficiency that a regular bike chain. For a front wheel, even a cardan sytem is a real pain though. And channeling only ~20% of available power to the front would result in great handling improvement, for a limited amount of losses. It could even be programmed to kick in only above given power and torque figures, as those would imply an especially steep hill or deep sand/snow section. 60r/40f or 70r/30f power spread would be perfect there I suspect.
 
I need you to brainstorm with me, and hope to gain knowledge on how wel magnet gears perform. What kind of air gaps can they deal with, and what torque to expect? I would prefer to not have to laterally overlay between wheel and drive, as that's one of the limitations of a chain I was looking to overcome in the first place.
 
Converting the tire could be as easy as sewing a cloth strip lined with magnets in place behind the tread. In case of a rim, it could be easier still, and not mess with the tire (disposable item). Or a special magnet tube, even easier...
 
When more than one gear ratio is needed, this could all happen near the crankset. Plenty of technology exists that could be converted for that purpose, even variomatics.
The drive system would need a freewheel in there somewhere for most of us.
 
Imagine, a bike with no chain to lube, and smoother power transmission from pedal to tire...
 
Your thoughts on this crazy idea, please!
 
thanks,
 
J

Cherryman

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Re: Magnetic gears, for a bicycle. Chainless bike, dragless drivetrain
« Reply #1 on: January 17, 2012, 07:43:22 PM »
Hi Cloxxki,

Intresting concept.

I played around with a bike gear/flywheel and cvt a while back (Just as a design study)

Here was my simplest version of magnetic driving, no gears.
(ignore the stuff on the back it is part of the flywheel construction)

But on the subject, the torque will be the main obstacle I guess.
It would be intresting to see if "skipping" when there is too much torque, make some kind of gearing.

Ideal would be a small magnetic CVT with a flywheel. 

Edit: Wrong picture, that one send us backwards. ;-)

Anyway, after this design study I came to the conclusion that having a good , simple CVT gear drive system could be very usefull to all kind of energy related issues.  I abandoned the bike, and still funneling around with an easy CVT design.

Cherryman

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Re: Magnetic gears, for a bicycle. Chainless bike, dragless drivetrain
« Reply #2 on: January 17, 2012, 11:01:25 PM »
Here is a nice vid to help see possibilities:

http://www.youtube.com/watch?v=7ZpTIpLJxQo

Cloxxki

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Re: Magnetic gears, for a bicycle. Chainless bike, dragless drivetrain
« Reply #3 on: January 17, 2012, 11:28:30 PM »
Thanks for your response! Great minds from great countries think alike...


As Dutchmen we find places to stick a CVT on a daily basis, don't we?


All,
Does anyone know about electro-enhanced magnetic gears? Does it exist, is it viable?
I am think of this to get a much greater peak torque performance from a setup.
For instance, if peak torque would be surpassed for 5% over a whole ride, a battery might be on stand-by to kick in the anti-slip torque support just in time before magnetic traction is lost. Not to aid propulsion, just to prevent the chain "from" temporarily becoming very elastic. If this would be possible, it would help the application of magnetic gears to bicycles greatly.
Thanks in advance for your insight here.

Cloxxki

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Cherryman

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Cloxxki

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Re: Magnetic gears, for a bicycle. Chainless bike, dragless drivetrain
« Reply #6 on: January 19, 2012, 11:09:37 AM »
Now this one is intresting too

http://www.youtube.com/watch?v=ludLU4_6ZDM&feature=related
I saw that also.
From a small "chainring" it gets the "wheel" turning quickly, at a 90º angle.

The obviously weak torque is however introduced as a convenient safety feature. On a bike, it would not make it up the slightest hill.
 
I am very much interested to learn whether a magntic gear link can be boosted turning the sytem (partly) into electromagnets. If possible, it might get a strong link from an otherwise feeble bunch of zen magnets, to offer an example. There's some nice zen magnet gearboxes out there on Youtube.
 
@Cherryman ik heb je een bericht gestuurd.

neptune

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Re: Magnetic gears, for a bicycle. Chainless bike, dragless drivetrain
« Reply #7 on: January 19, 2012, 05:55:49 PM »
I have been watching this thread with interest , but have refrained from posting to let other people have a say .On a world wide scale , the bicycle is by far the most used form of mechanised transport . Its great advantages are low cost and efficiency . Whilst chain drive has its drawbacks , a well maintained chain can have an efficiency of 95% or better . It is easy,light , and cheap to replace . The bike is the nearest thing we have to a practical overunity device . Although it is NOT OU , it is typically 3 times as efficient as walking ! I do not say that it is incapable of improvement , but that is not going to be easy . If it is not broke , do not try to fix it . Any device that replaces the chain drive must be lighter , or cheaper , more efficient , or more long lived . Or preferably all of the above . And that is a tall order . If you really want to improve the bicycle , invent a combined battery/motor unit that weighs less than a Kilogram and has a range of at least 100 miles , at a speed of not less than 15 Miles per hour . On the other hand , full marks for thinking about it .

Cloxxki

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Re: Magnetic gears, for a bicycle. Chainless bike, dragless drivetrain
« Reply #8 on: January 19, 2012, 06:12:49 PM »
@neptune:
Having been born in the Netherlands, and having designed some currently available performance bikes, I am well aware :-)
 
The bicycle is one of those technologies which was near perfect from the get-go in the 1800's. Double triangle frame, steel chain.
 
I am not only looking to improve efficiency, but also remove drivetrain maintenance (and grease).
And for a very specific application, where a chain just gets in the way of the feet. If you want to know: fat bikes. Mountainbikes with bicycle tires that resmble donuts, 3.7-4.8" wide. The wide tires themselves pose some fitting and compatibility issues, it would be great to remove the chain.
And for super high-speed road- and track bikes, not having an external drive train at all would reduce air drag, and enhance esthetics (very important for bike enthusiasts).
 
If I consider a regular chainwheel and chain, where the chainwheel's teeth are shallow, resulting in limited torque capability, to compare to a magnet gear:
When the chainwheel would be turned into an electromagnet, the chain would stick much better to the chainwheel, and skip over the teeth only at much greater torque figures. Presuming a well-tensioned chain, I don't see the chain suffering ill affected from the magnetic attraction. Releasing the chain costs the same as the initial pull delivers, right? I am interested to learn the Energy used up by such a magnetic chainwheel, and then extrapolate that exemplary concept to true magnetic gears. Just boosted. I honestly can't figure out how to calculate battery use for such an electromagnet, as it would not be performing visible work, only prevent mangetic skipping.
 
I see that the torque on such system is limited, so I'll think both of a high-surface-contact type of interface, likely with multiple contact points, inverted magnetic chain wheels, but also this boost option. And if the boost would aid in larger air gaps, that would help a lot also.
 
Thanks for any thoughts,
 
J

Cherryman

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Re: Magnetic gears, for a bicycle. Chainless bike, dragless drivetrain
« Reply #9 on: January 19, 2012, 06:26:59 PM »
Hi J,

Got your mail and replied.

OT: I did some thinking on your terrain donut wheels and have made a little concept in my head.

I will see if I can make a drawing.

Would you mind it if the tires were adjustable  for terrain and high speed surface on the fly?  ;-)



Cloxxki

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Re: Magnetic gears, for a bicycle. Chainless bike, dragless drivetrain
« Reply #10 on: January 19, 2012, 06:44:09 PM »
Hi J,

Got your mail and replied.

OT: I did some thinking on your terrain donut wheels and have made a little concept in my head.

I will see if I can make a drawing.

Would you mind it if the tires were adjustable  for terrain and high speed surface on the fly?  ;-)
Retractable knobs, responding to pressure? :-) Been done.
 
These bikes exist BTW, it's the largest growing product ground in mountainbikes. People are loving it, and especially women appreciate the stability and float. Lacking leak power output might be a reason why they like wheels that are basically flywheels. And the fat tire increase rideability over rough terrain.

Cherryman

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Re: Magnetic gears, for a bicycle. Chainless bike, dragless drivetrain
« Reply #11 on: January 19, 2012, 07:21:08 PM »
Retractable knobs, responding to pressure? :-) Been done.
 
These bikes exist BTW, it's the largest growing product ground in mountainbikes. People are loving it, and especially women appreciate the stability and float. Lacking leak power output might be a reason why they like wheels that are basically flywheels. And the fat tire increase ride ability over rough terrain.

I came to post a sketch, see i got beated already!  Well, i had an idea among that line, .. anyway I will post it .

;-)

Indeed I visioned tires responding to pressure / centrifugal force.  In the picture you see three stages.
One has a pneumatic connection to the frame (which of course doublefunction as pressure tank ;)  This could also be a spring, or a cable.
The magnet connection makes the wheel actually hang loose,  the magnets are in attracting mode , so the wheel sticks to the drive wheel.  The the magnets provide the connection, the air and rubber the smoothness. Dirt and dust can easaly go between it, the wheel can freely pivot a little as well. 

You might need two of those drive wheels i think (not drawn).

neptune

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Re: Magnetic gears, for a bicycle. Chainless bike, dragless drivetrain
« Reply #12 on: January 19, 2012, 07:33:51 PM »
@Cloxxki . As a bike designer you have probably forgotten more about bikes than I will ever know . I like to add my views on various subjects . My views are often controversial , but at least they are logical most of the time . Often , my aim is to stimulate discussion . At 66 years old I dont do a lot of radical offroad stuff , but I ride at least 10 miles a day on the road . Mountain bikes are fine off road , but they are hard work on the road . But at least these "fashion victims" get some extra exercise . Somewhere I have seen magnetic drives on the internet that actually claim overunity . See Peter Lindemanns book . Now that WOULD Be worth the cost and the weight .

Fester

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Re: Magnetic gears, for a bicycle. Chainless bike, dragless drivetrain
« Reply #13 on: January 19, 2012, 08:43:10 PM »
How about a Tesla style bike? Turbine "pump" at the pedals, and turbine at the back wheel. And it would make a sound that would either make people ask questions or toss colorful words your way :)

Cloxxki

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Re: Magnetic gears, for a bicycle. Chainless bike, dragless drivetrain
« Reply #14 on: January 19, 2012, 10:11:00 PM »
@Cloxxki . As a bike designer you have probably forgotten more about bikes than I will ever know . I like to add my views on various subjects . My views are often controversial , but at least they are logical most of the time . Often , my aim is to stimulate discussion . At 66 years old I dont do a lot of radical offroad stuff , but I ride at least 10 miles a day on the road . Mountain bikes are fine off road , but they are hard work on the road . But at least these "fashion victims" get some extra exercise . Somewhere I have seen magnetic drives on the internet that actually claim overunity . See Peter Lindemanns book . Now that WOULD Be worth the cost and the weight .
My conceptual designing stemmed mostly from obsession of specific details, my knowledge is limited to what I was interested in.
Good for you to keep your riding up that way, I'm making fewer right now.


My experience with mountainbikes is almost contrary to yours, perhaps due to my extra-tall body style. Only at insane road speeds I've found a skinny 23mm tire road bike to outperform a 60mm road slick tire mountainbike (on 700c/28"wheels). And the fat wheels outperform the road bike in any deciding moment: cross railtracks, cutting corners, emergency stops, overlooked potpholes, etc.
Also, I subscribe to the belief that bike wheels should be bigger, for a long list of reasons, all tieing in with performance as well. It's not here today, but larger bike wheel are a-coming. If you want it badly enough, a 36" wheeled bike can be gotten, with hellaheavy (moped quality) grooved road slicks, amongst others. Those will ride up staircases, litterally, and won't be impressed by any cobblestone road. Lighter tires are on the way. I am currently (modestly) promoting an in-between wheel size with with a typical MTB tire would come to 32", where 26.5" and 29" are currently the norm, and 36" the freak exception.


I am a bit of a bike nut. I regard road handlebars as uncomfortable in any of the many hand positions, and the same for broomstick shaped MTB bars. The optimum IMO is somwhere halfway, grip angledd outward and back, as "comfort" bikes. It doesn't mean "slow" in any way, just comfort.