1998 Kestrel KM40 Airfoil 55cm ‘Mango’

This bike is a landmark in cycling history, one of the first seat-tube-less designs produced, looking futuristic even by modern standards. Best for 5’6″-5’10” riders. Made in the USA, weightless carbon frame/fork, Rolf wheelset, upgraded modern Specialized cockpit, Dura-Ace drivetrain, and stunning ‘Mango’ color. Bikepedia indicates MSRP $3,100

What makes this bike special:

Radical “Airfoil” Geometry. Most bicycles rely on a “double diamond” frame for structural integrity. The KM40 engineering focused on reducing aerodynamic turbulence between the rear wheel and the seat tube. It eliminated the seat tube entirely, using a massively overbuilt, blade-like down tube and reinforced chainstays to handle the pedaling forces. This design was intended to provide “dirty air” a clear path away from the bike, theoretically making it faster in a straight line.

Carbon Fiber Pioneering. Kestrel was the first company to produce a commercial all-carbon bicycle frame (the 4000 in 1987). By 1998, they had mastered monocoque construction, which allowed the KM40 to be molded as a single structural unit rather than joining tubes at lugs. This gave the bike its seamless, organic look and high strength-to-weight ratio.

“Illegal” Design. The KM40 is famous for being UCI-illegal for most sanctioned road racing and time trials. The UCI (cycling’s governing body) eventually enforced the “lugged” or “closed triangle” rule, which banned frames without a seat tube. This solidified the KM40’s status as a “rebel” bike, highly sought after by enthusiasts and triathletes who weren’t bound by UCI regulations. Unlike many early carbon experiments that were prone to cracking, the KM40 gained a reputation for being incredibly robust. 

650c Rolf Vector Pro Wheelset is one of the most recognizable wheelsets ever made, the gold standard for aerodynamic performance and speed. Its most defining feature is the Paired Spoke Design, which pairs spokes at the rim to neutralize the lateral (sideways) pull of the spokes on the rim. This wheelset uses 14 spokes instead of 32. Fewer spokes mean less “wind churning” turbulence and better aerodynamics.  Together with a smaller wheel diameter, this makes the wheelset incredibly light, fast, and aerodynamic. It also looks incredibly cool.