Looking ahead to the final @LeTour on Stage 20 and it’s going to be decisive. Time gaps by the time we get there will be close & because of the unique nature of the profile there are a few different aspects that will affect the outcome of the TT.

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Firstly let’s break down the course itself. Starting in Lure and finishing up La Planche des Belles Filles. Three main sections – 1st a flat non technical section to Le Raddon, 2nd a gentle gradient to Col de la Chevestraye before a descent, then 3rd the climb to LPdBF.

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Aerodynamics is of course paramount with any time trial, but here rider/bike weight and setup is going to have a significant impact on the race. Tyre choice will be crucial.

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To the first time check, a change in mass of 1kg has minimal impact – for a 70kg rider with good aerodynamic drag and 400w power output in the aero position – just a 2sec penalty over ~18min.

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The second part including Col de la Chevestraye is more of an issue with a 4sec penalty over ~23min.

But up the final climb (~18min), there is a 13sec penalty for an increase in mass of 1kg. This adds up to a total of 19sec penalty over ~60min.

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Tyre choice is arguably more important however. If we take two tyres from this list, with a difference in Crr of ~0.0007 (for example a Vittoria Corsa Speed vs. a Continental GP5000), then the slower rolling resistance tyre has the following penalties:

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9sec over the 18min flat first section, 10sec over the Col de la Chevestraye middle section, and then an 8sec penalty up la Planche des Belles Filles. A total of 27sec slower.

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Riders are of course governed by sponsors but will be looking to use the best kit that they can to achieve the lowest weight and highest performance. This will mean light components and fast rolling tyres.

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Don’t forget about aerodynamics however. If a team used lighter components that were less aero – a 1% increase in aero drag must be combined with at least 400g of weight savings for there to be a net benefit. If you can’t get 400g of weight savings, keep the aero kit.

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