Steep angled seat tubed bikes will be non-existent, as will LeMondesque shallow angled seat tubed bikes. In fact, seat tube angle will become largely unimportant as riders adopt systems for altering their seat positions and effective seat angles while riding. Virtually everyone will utilize a system such as the brand new Seat Shifter (an American product from San Carlos, California), which allows the rider to choose four different positions of the saddle in relation to the bottom bracket via a small handlebar mounted lever. Riders can set the Seat Shifter to provide their standard/ hill-climbing/ behind the bottom bracket position as the rearward most setting on the seat shifter, thus allowing three forward positions with a total of 4" of travel. When hill climbing, riders can move the saddle back, sit up, and climb in their most effective and efficient position. On a long climb, they can alternate between this position and the next forward position to change muscle group usage and reduce fatigue. On downhills and flats, riders can slide all the way forward and stretch out onto their aero handlebars, gaining a two to three MPH speed increase by dramatically increasing their biomechanical positioning, efficiency, and comfort. Once again, riders can alternate between this forwardmost position and its next closest position to reduce fatigue and enhance recovery. Not only will this type of system make cycling faster, more efficient, and more comfortable, but it will also eliminate almost all cases of lower back fatigue and Shermer/Solon neck.
That sums up my predictions for ultra-marathon bikes of the 90's. Happy trails and gears to you!