Another kind of limit has already been reached: Technology is now outpacing the bounds of what's allowed on the road for racers. Where Trek could be making bikes ever lighter – by radically removing sections of the frame – they often find themselves adding weight to bikes, simply to meet the minimum weight requirements of bike-racing authorities. Don't think you'll see frames get freakier in the peloton anytime soon: Cycling's various governing bodies play an increasingly large part in regulating not just the weight of bikes, but what they look like. As Scott Daubert, who works with Trek's pro teams, puts it, "They want a bike to look like a bike."
With the bicycle's enduring, familiar form, you might look at these two bikes and wonder what's so great about the current one – both are constructed of carbon-fiber composite, after all. The answer is: a lot. The 2012 frame is over a third lighter and twice as stiff. In 1992, the 5500 used a single type of carbon fiber and a simplistic assembly that basically treated it like a metal tube, failing to take advantage of the directional-stiffness properties that make carbon fantastically tunable.
The modern version uses multiple grades of carbon that are as much as 36 times as expensive, and with the help of computerized finite-element-analysis software (FEA) that wasn't feasible in 1992, Trek can analyze the effect on a ride from something as small as changing the fiber direction of a single ply of carbon. Senior Composites Manufacturing Engineer Jim Colegrove says that our understanding of how to use carbon fiber properly has been the biggest leap. "It's beyond my wildest dreams what we're doing today. The techniques, the quiver of materials we pull from – it's just mind-blowing," he says.