Why is it impractical?
People on this website who know me will know that I’m involved in coaching at the highest level and I’m on first name basis with some pretty famous current pro tour cycling guys.
I’ve asked them much the same questions on pretty well everything hardware wise. The answer regarding wheels is that basically it’s all bets are off so the determining factor is compromise given the race conditions. In a totally dedicated individual or team time trial, disk and aero carbon wheels rule the day. However, they actually tend to be not the best in a pure classic road race or in a stage of a classic tour.
The single best example of what works best nowadays is the World Road Race Championship. You’ll see some guys riding deep disk carbon ZIPS, others riding ultra light Bontrager Triple X liTes etc etc, Mavic, Campags, it’s all up to the individual. In my personal conversations with a famous guy called Robbie, he says he goes for the Campag super strong aero bladed spoked wheels because they can stand up to a 70kmh sprint but ALSO go through unexpected holes over a 270km race and NOT lose their trueness. There’s your answer straight from one of the world’s best. In his words, a 16 bladed spoke front wheel (which accounts for 70% of wheel drag front vs rear) is 95% as fast as a tri spoke carbon HED, but much more complete over the distance of a pro road race - which ultimately means it’s the fastest wheel of all.
The devil is in the details.
Here is a close up of the model bike Lance rode. Count the spokes and look at the lacing. Now go look at your average bike.
On the Trek pictured the spokes come straight out in pairs from the hub. On most bikes the spokes come out at an angle and cross three other spokes on the way to the rim.
No, it’s true! Over one hundred years of development has indeed failed to come up with the best spoke design!
See http://sheldonbrown.com/power_wheel.html for the scoop!
*Not to be read except on April 1. No endorsement of the truthiness of this product is implied by this post. Your milage may vary substantially.
You probably meant UCI, right? Their rules are notoriously strict, on the grounds that cycling is a human competition using standardized equipment. Many innovative designs got discontinued the minute it was banned by UCI - the Trek Y-foil being one fairly recent example.
But the standard bicycle wheel is a very elegant design. Lacing patterns and materials have changed, but the basic construction remains the same. It’s a prestressed structure, like prestressed concrete bridges and skyscrapers; the aluminum (or carbon) rim is under compression, and the spokes are under tension. Disc wheels and tri-spoke wheels tend to be heavier because they aren’t prestressed structures (i.e. the disc or spokes are molded and cemented in place without any stress).
That’s just radial lacing though. That’s fairly common on front wheels, and I’ve seen it on the nondrive side of rear wheels.
The spoked wheel is a good design. The same basic design can serve in a wide variety of conditions, from Robbie Mcewen with 16 spokes to a loaded touring tandem with 48 spokes. Spokes can and do break, but replacing them is really easy.
Cheap. Light. Strong. Servicable. A good choice for most cyclists.