Significance
Stage 18 of the 2009 Tour de France around Lake Annecy saw Alberto Contador snag victor from Swiss TT king Fabian Cancellara by a slim 3 seconds in what was around a forty eight and a half minute effort for both riders. The generally flat course around the lake detoured up the category 3 Col de Bluffy, making climbing prowess more of an issue than in many time trials. During this stage Contador reportedly used a rebadged Lightweight Disc, which is known for its low mass and has a lenticular shape. Cancellara appeared to use Zipp’s Sub9, which is not quite as feathery as the Lightweight, but has a more complex shape that bulges at the rim and then becomes flat near the hub. Did Cancellara’s wheel choice cost him the stage victory? Or on this somewhat hilly course would both riders have been better off with the H3c, which Lance Armstrong had often ridden to victory in previous Tours de France but abandoned in 2009 for a Lightweight Disc like Contador’s?
In the pages below, we’ll present the methodology used to explore which wheel is faster. We will then examine how each wheel performs in its intended habitat—installed on the back of a time trial bicycle. This contrasts with standard rear wheel tests, which typically focus on the performance of rear wheels in isolation by mounting them in standalone wheel struts. We will present the results as average watts to translate (also in grams of axial force) at 18 and 30mph for the crosswind ranges of 0-20 degrees, 0-12.5 degrees, and 7.5 – 20 degrees. We will also present a figure plotting the watts required to translate each rear wheel and bike combination at crosswind angles of 0,5,7.5,10,12.5,15, and 20 degrees at speeds of 18 and 30mph. All three wheels were tested with a 700x20c Vittoria Crono Tubular tire installed.
***Disclosure notice: the wheel samples and tunnel time were purchased and/or independently acquired by a third party not directly associated with BikeTechReview.com or the wheel manufacturers of the samples tested. BikeTechReview.com witnessed the testing and reduced the data. The third party would like to share their data in an effort to recoup a portion of their wind tunnel time investment.
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