Originally Posted by
gregf83
Because, unlike when you are lifting weights, on a bike you have gears that can be adjusted to find a comfortable cadence. If you use a heavier bike you will just adjust the gears and your cadence for a given set of conditions and end up putting out the same power as you would on a lighter bike but at a slower speed.
The notion that a heavier bike somehow puts a greater load on the cyclist is false. If it were true, you could achieve the same effect on a lighter bike by shifting up one gear and maintaining the same cadence.
There is a difference, however. A light bike "gets out of the way" of a strong pedal stroke. It accelerates as the pedal force peaks, so that the peak force duration is relatively short. A very heavy bike, however, does not accelerate away from the pedal at the same cadence, so the high force duration lasts longer.
When I first started tandeming, my legs hurt like the very devil after 30 miles, and I was accustomed to riding doubles and 400s in the mountains on my carbon single. The hills also last a lot longer and the descents are shorter. My tandem cadence is usually the same as my single cadence, BTW, so it's not that. Now I can ride centuries on the tandem, which is hard because the duration is longer than on my single and I still spend more time in Z4 than on my single, but my legs have adapted.
It's hard for me to tell if this has resulted in an improvement on my single because I'm now 66 instead of 63 when I started tandeming and yearly power drop-off has gotten faster since I've cleared 60. My guess is that it's a wash, though friends tell me that my short attacks are pretty convincing. It would be interesting for a younger person to experiment with this. Do hilly group rides on a 100 lb. bike, backing off your competitors one level.
I have a couple of champion ultra racer friends who, in their younger days, would come out to the group rides pulling a large dog in a kiddie trailer. They would still drop us on the hills, and we weren't
that slow, most of us finishing RAMROD in the first 100. It was pretty funny, average duffers compared to the real deal. I don't know if they got anything out of that other than being able to ride with us and still have fun.