How does a cyclist lower their center of mass? Well, you can be shorter, that works pretty well. Or cut yourself off at the knees, but that has other side effects that I don’t want to get into right now. You could also lower the bottom bracket like Look and Eddy Merckx used to do (I think they raised their BB to the standard height recently).
Buth the real solution is that in most cases – at least in the cycling world, taller means lankier and that means that proportionally, the distances and angles between legs, arms, handlebars, saddles, and pedals start being very different – and should be much more extreme – than the scaled-up picture model of the 5’10” rider on a 56.
I have found over the last 23 years of riding that when I lower my bars, two things happen. First, I have better control over my machine. Second, I go faster. After having my bars as low as they would go on my R3 and consistently feeling they were a bit too high, I bought a 17 degree stem for my R3 which lowered my bars by 2cm- more than I thought I wanted. The results were astounding. Not only does my bike handle better, but I ride about 1-2kmph faster on flats and on climbs. The speed factor can be attributed to freakish bio-mechanics (that may be unique to my physiology) and/or increased aerodynamics, but the bike handling is, I believe, directly related to my lowered center of mass. In fact, John – who is also an Eros Poli-sized rider such as myself – noticed how good a low, aggressive position feels after borrowing one of my bikes during a visit to Seattle.
The bottom line is that you have to be comfortable on a bike, and that means different things to different people based on their size, flexibility, and style of riding. That said, I urge tall riders to experiment with riding the smallest frame you can while still getting enough saddle height and top tube length needed to ride efficiently – and then ride your bars as low as you can. If you need an example from the pros, take a look at Axel Merckx’s position (at the top of this post, as well as compared to Floyd Landis above), or keep in mind that Greg Rast on team Astana had Trek build him a frame with the dimensions of a 61cm frame with the head tube height of a 56cm frame – and slams his handlebar stem right down on his top tube.
It’s all about your center of mass, baby.