Light weight vs aero - my take

Everything about building wheels, glueing tubs, etc.
User avatar
silvalis
Posts: 472
Joined: Mon Sep 07, 2015 1:02 am
Location: Aus

by silvalis

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

by Weenie


peted76
Posts: 254
Joined: Mon Jun 23, 2014 10:30 pm

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....

sawyer
Posts: 4511
Joined: Fri Dec 15, 2006 7:45 pm
Location: Natovi Landing

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)
----------------------------------------
Stiff, Light, Aero - Pick Three!! :thumbup:

User avatar
ergott
Posts: 2867
Joined: Tue Apr 18, 2006 3:03 am
Location: Islip, NY
Contact:

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.

Sent from my SM-G920V using Tapatalk

jeanjacques
Posts: 126
Joined: Thu Apr 14, 2016 11:01 am
Location: France

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.

User avatar
BeeSeeBee
Posts: 492
Joined: Mon Dec 21, 2009 6:00 am
Location: Bay Area, CA

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
Posts: 36
Joined: Mon Feb 17, 2014 1:46 am

by vamoots58

ergott wrote:You lost me at 140psi.


Sent from my iPad using Tapatalk


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

User avatar
mellowJohnny
Posts: 485
Joined: Thu Aug 16, 2012 12:56 am
Location: YYZ

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. :-)

Post Reply
  • Similar Topics
    Replies
    Views
    Last post