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PostPosted: Wed Jul 18, 2012 10:46 am 
retrobike rider
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random thought, and please humour me on this.
could magnets (strong opposing types) be used to create frictionless movement on certain bike components such as bike pedal axles, wheel axles, headsets etc....


just sat here spinning a pedal at my desk and the thought entered my head.
would be cool to see a pedal spin on its axle all day long.....


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PostPosted: Wed Jul 18, 2012 10:49 am 
Gold Trader / PoTM Winner
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Would be heavy, to create enough force to oppose the wieght/power of the rider. Unless you use electro-magnets, but then you need batteries, would need to charge them up, and would be equally, if not heavier.....

....halfway through a ride and the bearings start grinding... "shite, need to charge the bike up" :lol:

But then, I'm not an engineer :wink:

G


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PostPosted: Wed Jul 18, 2012 1:09 pm 
BoTM Winner / Gold Trader
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I've been experimenting with telekinesis when I crash. The project is still in the development stage.


Anyone got a band-aid?

(or plaster, for you guys who speak all funny).


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PostPosted: Thu Jul 19, 2012 7:30 pm 
Gold Trader / MacRetro rider
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FMJ wrote:
Anyone got a band-aid?

(or plaster, for you guys who speak all funny).


Says he :wink:
http://www.wikihow.com/Understand-Canadian-Slang


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PostPosted: Thu Jul 19, 2012 7:45 pm 
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How many of you believe in telekinesis? Raise my hand...


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PostPosted: Thu Jul 19, 2012 8:11 pm 
retrobike rider
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Problem with magnets is 'drag/friction' (Eddy Currents) when one goes over the other, if this is less or more than some nice bearing I don't know. Of course you could use this problem to your advantage, possibly of dynamo style and run your Di2 ;)

I don't know about the weight problem though as two of the modern strong magnets when you try to ram them together, even when small, can be extremely hard to ram them together.


Though you still have the problem of seals, it's the seals in a biking system that take create the more friction. Rip them out, use some light grease in a pedal or wheel and they run for ages.


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PostPosted: Thu Jul 19, 2012 8:47 pm 
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Slightly loose bearings are better than tightish, ball bearings roll quicker in a wheel if there is a fraction of play,

External BB's get me, all those dragging seals, you could get more free spin out of old kit with oil (like an engine) than with most modern cycle bearing set ups


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PostPosted: Thu Jul 19, 2012 9:19 pm 
BoTM Winner / Gold Trader
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dyna-ti wrote:


Beauty.


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PostPosted: Thu Jul 19, 2012 11:55 pm 
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greenstiles wrote:
Slightly loose bearings are better than tightish, ball bearings roll quicker in a wheel if there is a fraction of play,

External BB's get me, all those dragging seals, you could get more free spin out of old kit with oil (like an engine) than with most modern cycle bearing set ups


It is how the whole system operates that is important. The drag on bottom bracket works is a tiny amount relative to the work it does.

Have you turned an engine over by hand?


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PostPosted: Fri Jul 20, 2012 7:51 am 
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in spin tests, new external BB's don't spin hardly as much as some older systems, if you include wheels as well...all that drag adds up. (perhaps i sholdn't have mentioned engines as they are under compression)

Grease or oil that's the real question with ball bearings.


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