Carbon wheels, why would you bother?

[jowwy]

Fair play @Dusty Bin your like a dog with a bone, just wont let it go

 

[Dusty Bin]

I already have. But if you are unable or unwilling to see it, that is fine with me.

But you simply have not - and seem unable to. Which is fine with me..

There are no circumstances under which two identical bicycles (with differing rim weights) ridden by identical riders, using identical power, over an identical distance, will use a different amount of energy.

 

[Dusty Bin]

Fair play @Dusty Bin your like a dog with a bone, just wont let it go

Fairl play jowwy - you keep chipping in with meaningless banalities which do nothing to further the discussion..

 

[Dusty Bin]

Sit at a set of lights with a load of Bromptons and you will notice how they tend to be quicker away.

And that's definitely down to the rim weight, is it? Not the rider, or the gear choice, or any number of other factors? Maybe they should all ride Bromptons in the TdF? They'd fly up them hills..

 

[jowwy]

Fairl play jowwy - you keep chipping in with meaningless banalities which do nothing to further the discussion..

Cause there is no more discussion to be added, just differing opinion that goes round in circles

 

[GrasB]

Sit at a set of lights with a load of Bromptons and you will notice how they tend to be quicker away.

Sorry, I'm too busy looking up the road ahead to see where I'm going, on my 622x23 60/88mm rimed bike, to look behind me to see which bikes are pulling away quickly from the lights... on a 78" fixed gear... ... ...

 

[andrew_s]

There are no circumstances under which two identical bicycles (with differing rim weights) ridden by identical riders, using identical power, over an identical distance, will use a different amount of energy.

Take 2 identical bikes, each powered by an electric motor that delivers a constant power.
From the off, the bikes will accelerate until they reach a speed at which the constant input power is balanced by drag (aerodynamic, mostly). However the bike with the heavy rims will have taken fractionally longer to reach that constant speed, as it's had to supply extra energy to get the heavier rims rotating.*
Thus the bike with the light rims will reach the end slightly sooner than the bike with the heavy rims, leaving the bike with the heavy rims being powered for a little longer, using more energy.

* kinetic energy = 0.5 * m * v * v
Bike 1 Frame=11kg, tyres/rims=1kg
energy to accelerate to 10m/s (22mph) = 550 + 2*50 = 650J

Bike 2 Frame=10kg, tyres/rims=2kg
energy to accelerate to 10m/s = 500+2*100 = 700J

at 100W, that's an extra half second.


[edit]
I put "10 meters per second in miles per hour" into google, since the conversion factor isn't in my memory banks, and amongst the hits beneath the answer, the following Yahoo Answers page caught my eye, in which the "best answer" managed to calculate that half the speed of light was 26mph
http://answers.yahoo.com/question/index?qid=20130313231251AAPKwj3

 

[400bhp]

discussion..

[/quote]

 

[400bhp]

But you simply have not - and seem unable to. Which is fine with me..

There are no circumstances under which two identical bicycles (with differing rim weights) ridden by identical riders, using identical power, over an identical distance, will use a different amount of energy.

Fail.

 

[Dusty Bin]

Fail.

Good post. And yet, you haven't been able to disprove anything I've said. Simply saying 'wrong' and 'fail' repeatedly doesn't actually make you correct.

 

[Dusty Bin]

Take 2 identical bikes, each powered by an electric motor that delivers a constant power.
From the off, the bikes will accelerate until they reach a speed at which the constant input power is balanced by drag (aerodynamic, mostly). However the bike with the heavy rims will have taken fractionally longer to reach that constant speed, as it's had to supply extra energy to get the heavier rims rotating.*
Thus the bike with the light rims will reach the end slightly sooner than the bike with the heavy rims, leaving the bike with the heavy rims being powered for a little longer, using more energy.

The fact that lighter rims will accelerate faster than heavier rims is understood and I don't think that is in dispute. But both riders will have performed the same amount of work to cover the same distance, regardless. This assumes that you turn the pedals more than once - and if you do, conservation of monentum comes into effect. And even if you did only turn the pedals once, the result would be the same, assuming all else is equal.

Anyway, I've said all I can be bothered to say on this topic, tbh. It could quite easily go on for another 7 pages, I'm sure. I'll just refer back to my original reply on this thread and then leave it there. There are far too many theories, laws and calculations going on here to make anything clearer from a practical point of view.

Rotating weight is largely irrelevant on any wheelset, except for some very minor (and very temporary) benefits. What matters more is the overall weight.

 

[400bhp]

Good post. And yet, you haven't been able to disprove anything I've said. Simply saying 'wrong' and 'fail' repeatedly doesn't actually make you correct.

I don't need to Black and Yellow.

The answers have been provided already.

I don't help educate those that don't want to be helped.

 

[jowwy]

I don't need to Black and Yellow.

The answers have been provided already.

I don't help educate those that don't want to be helped.

Is that who this guy is

 

[Dusty Bin]

The answers have been provided already.

As have mine. And agreeing with someone else who may be incorrect does not make you correct either. The difference between lighter rims and heavier rims is marginal at best, and irrelevant at worst. But if you don't agree with that, then that's fine. Who knows, one day you may have an original thought of your own..

 

[400bhp]

As have mine. And agreeing with someone else who may be incorrect does not make you correct either. The difference between lighter rims and heavier rims is marginal at best, and irrelevant at worst. But if you don't agree with that, then that's fine. Who knows, one day you may have an original thought of your own..

The earth isn't flat.

You don't understand physics.

There is nothing else to discuss.

You are an utter moron.

Black and Yellow.