Originally Posted by
Bacciagalupe
Evidence: You can start with the very basic empirical fact that, as previously mentioned, a time trial bike is both heavier and faster than a standard diamond-frame bike. An über-light racing road bike can be 12-14 pounds, and an über-light TT is more like 16 or 17 and will leave the 12 lb bike in the dust. Similarly, as I previously mentioned, aero and disc wheels are much heavier than standard wheels but are faster (unless there's a stiff cross wind). Aerodynamics is far more important factor than weight.
Not my typical riding situation. That is true for a situation where acceleration is not a factor, drafting is not a factor, and climbing is limited.
Originally Posted by
Bacciagalupe
You can continue by checking out the world's fastest HPV, the
Varna Diablo II. Max recorded speed on the flats: 82.3mph. Weight: 60 lbs.
Again hardly a normal riding situation. Dead flat and probably pushed or towed up to speed
Originally Posted by
Bacciagalupe
I have heard of a study where a researcher plunked a 5lb weight in a downtube, and a group of pro racers couldn't distinguish between a loaded and unloaded bike. I'll see if I can find the reference.
I am pretty sure they didn't climb any mountain passes in that test.
Originally Posted by
Bacciagalupe
Theory, as best I understand it: Weight affects acceleration, and that's it. Once in motion, the primary force slowing down the bike is friction, specifically aerodynamic drag, which increases at roughly the square of velocity. Once you go above 12mph or so, even tiny increases in your drag coefficient will slow you down much more than adding weight. Above 18mph, you need huge increases in power output to gain tiny increases in speed.
In practice when riding with others accelerations are frequent and important if you intend to stay with a group. Accelerating out of corners is where folks most often are dropped in my experience.
Originally Posted by
Bacciagalupe
When climbing, you're fighting gravity; most (non-pro) riders won't ride fast enough up a hill for drag to be a major factor. Even here, though, weight is a smaller factor than you think;
Chris Carmichael, Lance Armstrong's coach, describes the impact of adding 2.5kg (~5 lbs) as adding 38 seconds off of a 20-minute long, 5km, 1200 foot climb -- huge for a pro, noticeable for an amateur racer, inconsequential for everyone else.
I don't consider 38 seconds inconsequential if riding with others who I have to work hard to keep up with. At that point it becomes VERY consequential. Another way of looking at it is that no matter what your energy output is still increased by lifting 5 pounds 1200 feet.
Originally Posted by
Bacciagalupe
Subjective rider perceptions about weight are basically BS and highly inaccurate; the human body simply isn't that well calibrated, and has absolutely no reason to develop that ability, and cognitively it would be a very "expensive" one to develop. Perception of performance isn't much better, especially when a new or expensive bike is involved.
it isn't all that subjective if you ride with the same people and drop them or get dropped depending on which bike you ride.
Originally Posted by
Bacciagalupe
From what I've gathered, the only truly objective way to determine the efficiency / performance of a bike is with a power meter. Even an HRM might not do it since your biological efficiency will vary from day to day, so you'd need a large pool of samples.
So basically if I disagree I need to have a large pool of samples, but you can cite your own impressions and irrelevant time trial and HPV references.