Road Racing & Aero Wheels

[Pumpkin the robot]

What about the stored energy when you are on the flat? A heavier wheel will not require as much energy to keep it going when it is at speed.
You can make any scenario and use figures to prove a point, but at the end of the day it is not lab conditions and it is virtually impossible to measure every detail that could make a difference. I had a discussion with someone that was involved with the design of racing car engines and we were discussing flywheel weights and he told most people make the flt wheel lighter as it spins up quickly, but when it is heavier it wants to keep spinning so you do not lose momentum and that helps keep the revs up. It wasnt as straight forward as that, as
the weight and diameter of the wheel make a difference.

 

[Citius]

What about the stored energy when you are on the flat?

All I would say is the angle of the road doesn't change the underlying physics.

 

[Pumpkin the robot]

Does the centrifugal force of the wheel not make a difference?

 

[Citius]

sorry, I don't know what you mean. Assuming you mean centripetal force, how would the angle of the road alter that?

 

[oldroadman]

Lots of lovely theory. Meanwhile, in the real world, roads tend to go up and down a bit. Light wheels make climbing easier (relative term!), and as the majority of people are not particularly skilled descenders, "stored energy" is a pointless concept as braking (generates heat=energy) will convert it and it won't be available to the rider. When it does work is on indoor tracks, which is why disc wheels (quite heavy) are effective as they are aero and riding a fixed gear helps to ensure a smooth ride where the rotational mass helps. Not for nothing are any form of additional weights banned in disc wheels.
All I know from a bit of experience is this - light wheels work best, and all the stored energy theory is nonsense from the instant you brake, which is what happens in road races when you go round corners, descend, slow to avoid the fallen, etc.

 

[Citius]

The term 'stored energy' is misleading, I think. But the principle that a heavier wheel requires a higher force to accelerate it - an input which is then returned in the form of slower deceleration, is an actual law of physics.

 

[derrick]

I have just started using a set of cosmic carbone sle : wheels 2190 grams with tyres and tubes,have done 80 miles on them, previously i used Mavic Ksyrium Elite 2060 grams with tyres and tubes. It's really hard to notice a lot of difference climbing feels exactly the same, i do feel the aero wheels have an edge on the flat, but how can one be sure, as for the cross winds the aero wheels actually feel better all though the cross winds i have ridden in have been very light, so the jury is still out on that one. will know more when i start riding with people i know, there are a few of us are evenly matched but even then we all have bad days and good days, so who knows, One thing i do know is they look the b******s, So the feel good factor comes into play here. that always makes you faster, So if you like them and can afford them go for it.

 

[adscrim]

One thing i do know is they look the b******s, So the feel good factor comes into play here. that always makes you faster, So if you like them and can afford them go for it.

Amen!

 

[oldroadman]

The term 'stored energy' is misleading, I think. But the principle that a heavier wheel requires a higher force to accelerate it - an input which is then returned in the form of slower deceleration, is an actual law of physics.

Which is true, however we generally don't slow down gently to preserve momentum, braking occurs, and the "stored energy" gets used up as heat. Thus the law of physics which states that energy remains at a given constant level, but in different forms, friction generating heat in various quantities being a good example, via braking, bearing resistance and of course aerodynamic causes.

 

[Citius]

Unless you maintain a perfectly circular pedal technique where a constant force is maintained throughout the pedal stroke (which nobody does, regardless of what they might claim) - then the wheel will begin to decelerate every time you ease off the pressure. In other words, unless you are actively accelerating the wheel, it will be decelerating, regardless of whether you are braking or not.

The exception is obviously when going down hill - but that's a different law of physics

 

[Cyclist33]

i would just like to note for the record in response to the long post by y saddle that i was misquoted as i didnt say in another thread that a pair of my wheels was both stiff and compliant, as is stated. i did say they were stiff and comfortable, which i do not see as mutually exclusive terms, indeed in general terms i find myself more comfortable on a bike the less it lolls spongily .

 

[Cyclist33]

and i should also note that not everything in life must be quantifiable to be valid or valuable empirical evidence. qualitative evidence is of equal value as are the opinions of fellow beings. sadly this is not a view shared by everyone, particularly the conventional and unimaginative science type, of which there are disappointingly many these days!

 

[Citius]

and i should also note that not everything in life must be quantifiable to be valid or valuable empirical evidence. qualitative evidence is of equal value as are the opinions of fellow beings. sadly this is not a view shared by everyone, particularly the conventional and unimaginative science type, of which there are disappointingly many these days!

That may be true - but believing that certain types of wheels make you faster is not the same as being able to prove it. Which is why science can sometimes be the only reliable fall-back when the inevitable disagreement comes.

 

[Cyclist33]

btw did you mean 0.4 % less energy to accelerate lighter wheeled bike?

great post btw, just not the whole story!

I think you just caught him out there, however I doubt the irony of his statement will ever sink in.[/QUOTE

 

[Cyclist33]

That may be true - but believing that certain types of wheels make you faster is not the same as being able to prove it. Which is why science can sometimes be the only reliable fall-back when the inevitable disagreement comes.

yes but being able to prove it is not that important either if youre not trying to, ie if youre not bound by the need to prove that science is RIGHT it doesnt matter if it is or isnt.