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The cycling community had quite the shock on Stage 11 of the Tour de France yesterday when Tadej Pogacar cracked on the Col du Grandon, conceding 2’51” to Jonas Vingegaard on the 11.4km climb. The anti-disc brake brigade wasted no time in lighting up Twitter to blame the defeat on Pogacar’s disc brakes, something he ditched on summit finishes in previous years… but were the Slovenian’s brakes in any way to blame for his capitulation?
Zac Williams/SWPix.com
Of course it is worth pointing out that Jonas Vingegaard, winner of the stage and now proud owner of the yellow jersey, was also using disc brakes on his Cervelo R5, so it’s a rational argument to say that it was the legs and team strategy that did the talking rather than the equipment.
Presumably, the reason that Pogacar’s bike is under the spotlight is that in previous years at the Tour de France, the UAE Emirates rider has switched out his V3Rs disc brake frame for a rim brake model when tackling particularly arduous summit finishes.
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The switch to rim brakes is speculated to save around 300g from the total weight of the bike, and this seems realistic given that the 12-speed Campagnolo rim brake groupset is around 200g lighter than the equivalent disc version. The additional 100g of weight saving will be from the Campagnolo wheels, which Pogacar has previously switched out for the tubular version as opposed to the tubeless tyres that he usually runs.
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Of course, Pogacar is on a completely different bike this year, the Colnago ‘Prototipo’ which is rumoured to be the V4Rs, a direct replacement for last year’s bike the V3Rs. I was initially sceptical that this would weigh any more than the UCI weight limit of 6.8kg, but there are unconfirmed claims that the bike Pogacar rode for Stage 11 weighed in at 7.2kg.
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If this is indeed the case then Pogacar potentially had a 400g penalty over his rivals. Does the rim brake brigade, therefore, have a point?
For the sake of simplicity, we’ll just focus on the final climb of the day, the Col du Granon, and ignore any minuscule differences in aerodynamics between a disc brake and rim brake bike when travelling uphill at an average of 17.5kph.
The climb in question
The Col du Granon looked absolutely savage, especially coming at 139.1km into the stage after tackling other monstrous climbs such as the Col du Telegraphe and Galibier. The climb has a fairly constant gradient of 9.7% over its 11.4km length, peaking at just under 15%.
This is the second time that the Col du Granon has been used on the Tour de France, There were fireworks last time as well, with Greg Lemond going on to beat Bernard Hinault in the 1986 edition.
The maths
There are all sorts of software that can help us predict how much difference additional weight can make and due to the gradient and relatively low speeds this should give us reliable results. For the purpose of this we’re going to use the ‘Bikecalculator’ free software.
Zac Williams/SWPix.com
First it’s a job of putting in the known parameters such as the elevation, distance and gradient of the climb, as well as Pogacar’s latest known weight of 66.0kg and the bike’s rumoured weight of 7.2kg.
Looking at Pogacar’s Strava upload, we know that the climb actually took him 38:42 which is 17.5kph for the climb. We’ll be assuming no headwind and drafting effect for both scenarios.
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Now let’s run the software again, but with a bike weight of 6.9kg. That seems fair as it’s unrealistic that rim brakes could save more than 300g; to save further weight Pogacar would probably have to ditch the rather hefty SRM chainset.
Speaking of power meters, the software predicts that to ride the climb at the speed of Pogacar an average power of 398 watts needs to be held. We’ll plug that number back in with the updated bike weight.
The results
At the same watts, the same conditions and all else being identical, a bike weight of 300g less would save Pogacar ~8 seconds over the entirety of the climb; so although not insignificant, certainly not enough to have toppled any of the riders in front of him. Sorry rim brake lovers…
Should Pogacar swap bikes?
When Grand Tours can be won by just seconds, should Tadej Pogacar be switching bikes to something lighter? Well, other than sponsor obligations there are some other advantages to ditching the rim brakes, namely descending confidence. There’s also the small issue that the new Colnago Prototipo is very unlikely to even be available in rim brake form. This new bike is likely lighter, stiffer and more aerodynamic than the old model hence, why it’s the rider’s bike of choice.
Pauline Ballet/ASO
There’s also the fact that our calculations are kind of a worst-case scenario. The actual weight penalty is likely to be closer to 200g rather than 300g, bringing the difference on the Col du Granon down to just 5 seconds.
In my opinion, Pogacar would be a lot better off trying to save weight elsewhere; for example, his saddle isn’t the lightest and the SRM power meter is definitely one of the heavier in the peloton. The Col du Granon then was much more to do with legs, fuelling and team strategy than the weight of a Cadbury chocolate bar.
Do you think that Pogacar should have used his old rim brake bike? Let us know in the comments below…
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