Originally Posted by
terrymorse
I've heard that "acceleration is small and therefore insignificant" claim before, but I'm not convinced it is wholly accurate.
Yes, accelerations are low in bicycling, relative to a motor vehicle. But does that make them insignificant? I would think that acceleration is quite important to a track cyclist doing a standing start 250, or a road cyclist attacking on a steep climb, or the attacked cyclist trying to bridge back. Having attacked--and having been attacked--many times, I can say that getting up to speed quickly is pretty important for getting a gap.
A standing start track sprinter goes from 0-15 m/s in about 150 meters.
Okay so let's use my spreadsheet to calculate the power difference for 1 kg on a 0-15 m/s balls out acceleration
Lets say we accelerate at 2.5 m/s/s from a standing start up to 15 m/s.
For 80 kg total mass, that acceleration requires an average power of 1556 W for 6 seconds.
For 79 kg total mass, that acceleration requires an average power of 1537 W for 6 seconds.
So a power saving of 19 W for 1 kg of weight under those extreme conditions. Once up to speed the power saving is of course zero. It's not like a steady climb against gravity.
But we are not track sprinters banging out 1500W (and that's just the power required to accelerate the mass in a frictionless vacuum). We are talking about 2 endurance road bikes here. They are never going to accelerate at those rates and therefore the power savings in accelerating the mass will be insignificant (as Swiss Side showed in their criterium simulation with multiple sprints out of slow corners).