Light weight vs aero - my take

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silvalis
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by silvalis

I wish I was riding deep carbon wheels on social rides 1.5 years after starting.
Chasse patate

peted76
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by peted76

mike001100 wrote:Other areas, I can't quite draw a conclusion. Side winds, so far, seem the same wheelset to wheelset, perhaps slightly worse on the LW. On the straights and downhill? I can't quite put a finger on it, but it seems like the LWs lack momentum... how can I put it? The Reynolds took more effort to get going, definitely, but once they were up to speed, they just went... with the LW, once you stop pedaling (in certain situations), you can feel the wheelset stopping... This seems more evident downhill, where the Reynolds just seemed to pick up speed easier... where I didn't have to pedal with the Reynolds, I have to push with the LWs...


Rim weight is what you can't put your finger on, heavier wheels keep their speed up on the flats and downhill easier, simple centrifugal physics.

The 'question' posed by most people in the past comparing aero and lightweight wheels is how much do time/effort do you save on going up and getting up to speed out of corners in comparison to the time/effort saved on the flats and downhills. The answer to this should suit 'your' style of ride....

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sawyer
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by sawyer

peted76 wrote:
mike001100 wrote:Other areas, I can't quite draw a conclusion. Side winds, so far, seem the same wheelset to wheelset, perhaps slightly worse on the LW. On the straights and downhill? I can't quite put a finger on it, but it seems like the LWs lack momentum... how can I put it? The Reynolds took more effort to get going, definitely, but once they were up to speed, they just went... with the LW, once you stop pedaling (in certain situations), you can feel the wheelset stopping... This seems more evident downhill, where the Reynolds just seemed to pick up speed easier... where I didn't have to pedal with the Reynolds, I have to push with the LWs...


Rim weight is what you can't put your finger on, heavier wheels keep their speed up on the flats and downhill easier, simple centrifugal physics.

The 'question' posed by most people in the past comparing aero and lightweight wheels is how much do time/effort do you save on going up and getting up to speed out of corners in comparison to the time/effort saved on the flats and downhills. The answer to this should suit 'your' style of ride....


Yes, there's no doubt that just rolling along can be more enjoyable on wheels with a heavier rim for precisely that reason (if you have the benefit of hyperultrasensitiveperception)
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Stiff, Light, Aero - Pick Three!! :thumbup:

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ergott
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by ergott

The biggest difference most people feel is how the front end steers. No doubt super light rims respond quicker. That quickness is often confused for making the bike faster. It's mostly just a different feel.

As far as rotating momentum. The differences are small with respect to total rider/bike weight so total watts aren't very different.

The reason lighter rims feel faster is our connection to the bike is fluid (hands, butt, legs). A light bike/wheels feels more like its pulling from under you with each pedal stroke. A heavier setup will have less if this, but bottom line the difference is counted in seconds and tenths of mph.

It's not until I compare my A bike to my commuter (same fit) that I can see noticeable differences in speed. That's comparing a bike that has a dyno hub, boxy pannier, slower tires, and about 10lbs heavier.

The stuff you are comparing is a lot closer and real differences are miniscule.

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jeanjacques
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by jeanjacques

I ride with a friend who have just a very light MTB, on paved road, with my gravel (32c tires) and him with 2" tires (slick at the top), we ride at the same speed (around 20mph) and we have almost the same physical level. Each time, I think about all of this marketing about aero, weight, etc, but except the sensation (like message above), I think the real difference on the road are pretty marginal.

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BeeSeeBee
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by BeeSeeBee

^ The good news is that no guessing is required if you have access to a power meter and conduct some field testing!

To expand on what ergott mentioned, Dan Connelly took a stab at this back in 2010 and also concluded that a lot of what you "feel" doesn't really bear out.
http://djconnel.blogspot.com/2010/07/ve ... rmula.html

So we get the following for the power cost from the variation among the tested wheels:
front wheel rotational inertia: 0.030 W
rear wheel rotational inertia: 0.045 W
total mass: 0.26 W
aerodynamic drag @ 25 mph: 9 W


I also wonder how the Lightweight's carbon spokes (although aero profiled) compare to modern steel aero spokes in terms of rotational drag, that could be a factor as well, though I haven't seen any data for Lightweights.

vamoots58
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by vamoots58

ergott wrote:You lost me at 140psi.


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Agreed!!!! :shock: :shock: :shock: :shock:

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mellowJohnny
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by mellowJohnny

Alumen wrote:I am with you for wheels... 1) Aero, 2) Stifness, 3)Weight.

All in all, being a pure WW is a bit outdated I would reckon, pure aerodynamics, that's where your gain is !


Agreed. In fact this year I have *added* close to 700g to my bike vs. last year. Swapped out my Zipp 202 tubulars for some Mavic Carbon Pros (I broke my rear Zipp for the 2nd time in four years) and swapped my Fizik Arione CX Carbon saddle for a Romin Evo, but that was purely for fit reasons.

The difference? I honestly can only tell when I lift the bike off the wall. Out on the road I'm just as happy and the bike feels essentially the same once up to speed. Climbing feels the same - it's still hard. :-)

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