After releasing the original Speed Concept, the Kammtail Virtual Foil design offered impressive aerodynamics, with integrated storage that added to the overall design. The original was a great design – how would Trek be able to improve upon it? Making it lighter and faster is a start. Add in even more integrated storage solutions, better fit, and a simpler design that requires less assembly time, and you have the blueprint for success.
After extensive real world aerodynamic testing, the result is an all new Speed Concept that is better in almost every way.
Wind tunnel testing and CFD are great tools for use in creating wind cheating designs, but just what is the average wind speed and yaw that is encountered while riding a bike? As you might guess, it varies significantly which is exactly what Trek set out to find out. Way back in early 2009, Trek’s engineers created a mobile wind sensor system (pictured left) that gave real time measurements of yaw angle and wind speed, with other key data like GPS Speed, location, heading, and altitued. The sensor extended from the front of the bike and measured at 10,000 hz with it averaged to 100 hz for accuracy.
The sensor was calibrated at the San Diego low speed wind tunnel, and positioned so that the rider or bike had little effect on the sensor. According to Trek, the hardest part of the equation was developing an algorithm to turn the pressure data from the sensors into reliable information on wind speed and yaw angle. Eventually the sensor had to be moved to a scooter that rode behind the rider, since the data acquisition system had to be carried in a backpack on the rider, potentially affecting the cyclist’s natural speed variations.
After following riders around the Ironman Kona, Arizona, and Wisconsin courses at various speeds with multiple riders, Trek compiled the data to find just what is the typical yaw and wind speed encountered in various triathlons. Further testing was carried out by creating a mathematical simulation using the real world data that captures the physics of a bicycle race allowing Trek’s engineers to race virtual bikes head to head.
More real world simulations were used to validate the final design’s wind tunnel performance with the new bike saving a rider, who averages 20 mph on the previous SC, 99 seconds at Ironman Hawaii, and 148 seconds at Ironman Arizona on the new SC. In addition to wind tunnel testing of the final design, Fabian Cancellara hopped on the new bike at the Valencia Velodrome equipped with the new state of the art Alphamantis Aerostick sensor, which replaces the previously developed sensor. Fabian’s testing at the wind tunnel confirmed a savings of 30-40 seconds in a one-hour time trial.
You can get a lot more tech geek by diving into the Trek Speed Concept Whitepaper, but we’ll leave it at the fact that Trek put a lot of time and effort into the aerodynamics of the new bike.
Even if you’re not convinced on the aerodynamics of the new bike, the good news is there are a number of tangible improvements offered as well. Reducing the frontal area of the bike by 30% not only cut down on drag, but also allowed for the removal of 437g from the frame. With a refined KVF design, the new SC has a deepened fork profile, and the radical rear brake cover. The redesign of the frontal area also resulted in less hardware and increased range of fit over the previous bike.
Called the Speed Fin, the non-UCI approved brake booster acts as a fairing for the rear wheel saving 10g of drag. A UCI approved cover is also available that has a built in Di2 battery mount – the non UCI bike hides the battery in the seat tube. Trek claims the integrated brakes are now much easier to work on and offer more stopping power. The cables and housings on the frame are completely internal.
Nearly as much attention was paid to the aerodynamics of the storage options as was paid to the new frame. The result – the bike is faster with all of the additional boxes and packs. The Draft Box 2 was increased in size in order to fit a tubular tire or full flat repair kit, and sits behind the seat tube to extend the airfoil design. On the top tube, the Speed Box 2 carries your fuel in a silicone design that holds 8 gels or 2 flasks – and importantly, is easy to clean. A carbon computer cage is offered for the aerobars that holds a bottle and offers a place to mount your computer where you can actually see it. Finally, the 2-pack Aero bottle cage sits behind the saddle holding two bottles with room for more gear and improved aerodynamics.
Combined, Trek claims the storage options can save up to 253 seconds on an Ironman distance bike course.
The new Speed Concept 9 is offered in 5 sizes in both men’s and WSD, each with 6 stem options. Currently the new design is limited to the 9 series with framesets retailing for $4,999, and complete bikes starting with the 9.5 and 9.5 WSD at $5,999, all the way up to Team and Rider special editions available through Project 1. Maybe one of the best features for bike shops – Trek claims the new bike takes an entire hour out of the build time.