It's interesting that trackies in the 70s were trying to reduce weight that much. I don't think it's perceived as especially advantageous these days. The high-ish end track bike I'm assembling now will be a little over 8 kg (almost 18 lb). We also race much bigger gears (typically 95-110 gear inches in mass start racing, bigger for sprinting) than mentioned in the article (72 gear inches). The position that is considered aerodynamic is also much different -- there is much less focus on getting that insanely low, and instead the focus is on being narrow and getting the forearms parallel with the ground.
It largely is the streetlight effect: we all have or can easily get tools to measure weight, we all have significant experience with weight, etc... Aerodynamics are much more difficult, especially in the 1970s where you can't just do some CFD simulations on your computer. There also weren't cheap solid state strain gauges to outfit wind tunnels or the bike drivetrain. Since only tiny aero gains are available without banned aerodynamic devices, there isn't much optimization you can do and need sensitive tools.
Not sure if you know about Merckx's bike for his hour record - they did many interesting modifications to it aiming to reduce its weight
Yeah, Sheldon mentions it in this article. I don't think those mods helped. Weight has no impact on sustained speed.
> Weight has no impact on sustained speed.
On a nice track, assuming a perfectly smooth surface and zero elevation change, I'm willing to accept the effect may not matter enough to care. But introduce even just a little bumpiness or some elevation change (perhaps in the track curves), and it might matter for someone pursuing the hour record.
You're not going up and down the track during an hour record. Just doing laps at the bottom (zero elevation change). Track surfaces aim to be very smooth in general.
Rolling resistance increases linearly with weight, so it does have some impact.
Ok. Almost no impact. Worth keeping in mind we're talking about a system weight of like 180 lb vs at most 185 lb here (Merckx was ~163 lb), for a relative difference of up to 3%.
You slow down incrementally between every power stroke.
A heavier bike would slow down less. At the end of the day the energy is lost to friction.