Yet Another Cycling Forum
General Category => The Knowledge => Topic started by: andygates on 04 April, 2008, 07:57:27 pm
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http://www.activespoke.com/
Here's a novel idea: weights on your spokes. When you're moving slowly, they are at the hub and so have minimal effect; when you're moving fast, they move out to the rim and give you the rolling benefit of lots of delicious angular momentum.
Which all sounds like perpetual motion and snake oil, until the field tests, and the Joe Friel endorsement.
5.6 seconds a mile. That's a minute off a 10, more than two off a standard triathlon...
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I don't get it. It's still all extra rotating mass.
But a physicist will be along shortly I hope. :)
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It's not rotating mass, it's angular momentum wot counts (determined by mass and also how far it is from the axis and also how fast it's rotating)
So yes, I can see that for a flat or slightly rolling TT when you are maintaining a constant speed it could help. If you hammer up hills though it could be a bit of a different kettle of wotsits
signed, a passing physicist (or at least an ex-one;))
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Hmmmm.
F=ma says light wheels only help under acceleration. I suppose the theory is that once you are up to a constant and high speed, with zero acceleration, the extra mass just acts as a lovely flywheel.
Those masses at the rim would make it very hard to respond to an attack or to surge on a hill, but if you just wanted to stick at 25mph on the flat, I can see how it might work.
It's not an April Fool, is it?
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F=ma isn't the only thing though. m stays the same, but move - the moment of inertia increases.
So when you, for example, crest a hill and get that free push from gravity, you get to keep more of that free stuff in the wheel at the bottom when you run out onto the flat.
They're marketed for TTers and triathletes (triathletes are just wealthy, damp, rubbery TTers with less specialisation and more of an eye for gadgets). Responding to a surge is outside their design brief.
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The guy who broke the one hour record a couple of years back had ballast in his rims.
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Moser in the 1970s?
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Sosenka http://www.wolfgang-menn.de/sosenka.htm
I am not convinced that additional wheel weight can be anything but a disadvantage, assuming everything else remains the same.
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Is it just me that thought of the 1970's and these?
http://www.classic-cycle.de/oxid.php/sid/x/shp/oxbaseshop/cl/details/anid/0d9479de103a6c144.43563016/changelang/1
rattley rattley rattley
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Not just you, no :)
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Is it just me that thought of the 1970's and these?
http://www.classic-cycle.de/oxid.php/sid/x/shp/oxbaseshop/cl/details/anid/0d9479de103a6c144.43563016/changelang/1
rattley rattley rattley
Oh, WANT!
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I find it quite uncomfortable riding with ballast in my rim.
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You are awful ! :-)
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Hokum
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Snake Oil.
If you want extra weight on the rims, use heavier tyres like Schwalbe Stelvio plus. At least that stands a chance of saving you a decent amount of time through the avoidance of p***t*res.
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But I don't want extra weight on the rims all the time!
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Is it just me that thought of the 1970's and these?
http://www.classic-cycle.de/oxid.php/sid/x/shp/oxbaseshop/cl/details/anid/0d9479de103a6c144.43563016/changelang/1
rattley rattley rattley
So tempted. What do you think will happen, when they suddenly get an order for about 1000 of these from acf members! ;D
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Hmmmm.
F=ma says light wheels only help under acceleration. I suppose the theory is that once you are up to a constant and high speed, with zero acceleration, the extra mass just acts as a lovely flywheel.
Those masses at the rim would make it very hard to respond to an attack or to surge on a hill, but if you just wanted to stick at 25mph on the flat, I can see how it might work.
It's more complicated when you have wheels. As any fule synchrotron physicist kno, something moving in a circle is constantly being accelerated. On top of that, the wheel is fixed to a bike which is moving along the road. So at any given moment, the bottom of the wheel, in contact with the road is stationary, while the top of the wheel is moving at twice the speed of the bike.
Luckily the accelerations around the wheel balance each other out (the importance of perfectly balanced wheels) if you are rolling along at a perfectly steady speed. However, suppose you are pushing hard, stamping on the pedals - the bike will be making small accelerations with each stamp. That accelartion/deceleration is doubled at the wheel rim.
So if this device keeps the wheel moving at a more constant speed, then it's entirely possible it may reduce the amount of effort being lost to accelerations in the wheel and leave it for overcoming resistance.
It's not an April Fool, is it?
Quite likely!
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I'd order some to try out, but not at that price :(