Ask a physicist about the Law of Conservation of Energy, and they will tell you it states that ‘the total amount of energy in an isolated system remains constant over time’. Or, to paraphrase it into cycling terms: a rider only has a certain amount of energy, so don’t waste it.

Never is this more true than at the Tour de France, where riders can expend (and therefore must consume) upwards of 5,000 calories per day over three weeks – it’s no surprise so many of them suffer from ‘digestive issues’ – and every one of them, even the yellow jersey, is practically on their hands and knees by the time the Champs-Élysées finally hoves into view. Energy is a scarce resource, and just as some riders are better than others at maximising their talent, the same is true about tailoring their efforts appropriately. It’s worth bearing the Conservation of Energy in mind when we assess the performance to date of the riders so far.

Are BMC’s tactics really that good?

Earlier in the week, Sky came under some fairly heavy criticism for not riding closer to the front to ensure Bradley Wiggins – who crashed out of last year’s race with a broken collarbone – had the best possible chance of avoiding crashes. Meanwhile BMC were roundly praised for regularly putting themselves on the front of the peloton in the closing 15-20km or so of stages, not because they were trying to set up a sprinter but because it is part of their strategy for keeping defending champion Cadel Evans out of trouble.

There is some considerable merit in the criticism of Sky, just as some of the praise of BMC’s tactics is also correct. But is it really so clear cut? I’m not so sure.

Burghardt has kept Evans out of trouble, but at what cost to his energy reserves? (image courtesy of BMC)

Sky team principal David Brailsford often talks about the cumulative benefit to be derived from incremental gains, and the converse is true in terms of the eventual impact of decremental losses. Start with one of cycling’s basic truisms: it takes more effort to ride at the front than it does to ride behind the man at the front. That’s why Evans is never at the front of the BMC line – a Marcus Burghardt or a George Hincapie hammers away at the front while Evans enjoys the benefit of sitting in the ‘hole in the air’ created behind them, while also enjoying a position near the front of the peloton where he is least likely to be caught up in a crash.

But the downside is that Burghardt and Hincapie expend considerably more energy than they would if they were sitting in the middle of the peloton. That has no discernible effect in the first week of the race. But what about in week three, when Evans really needs his team to chase down a dangerous break in the Pyrenees and they run out of reserves?

By comparison, will Sky benefit down the line from the admittedly riskier tactic of hiding their riders away inside the peloton for long stretches in the race’s early days? (Although they have been more prominent at the front in recent days, ostensibly adopting BMC’s tactics.) And how much will Vincenzo Nibali and Denis Menchov, whose Liquigas and Katusha teams do not have the same strength on paper as either BMC or Sky, benefit from having hidden to the point of near-invisibility all week?

It’s hard to quantify. But I do wonder whether BMC’s early shows of strength – though impressive – will end up costing them later in the race. After all, riders only have so much energy which they need to conserve as much as they can, and nobody ever won the Tour by flexing their muscles in the first week of the race. There is a fine balance between mitigating risk and having a relatively fresh team in the final week – BMC have opted for the former, Sky arguably the latter.

We shall see. Sky’s first week riding may have shown less panache than BMC, but it might ultimately turn out to be more efficient. And one day those marginal energy savings could add up to the team effort which wins the Tour.

To sprint or not to sprint?

I’ve been a big fan of the Tour’s new points system since it was introduced last year. By reducing the number of intermediate sprints to one and increasing the number of points and placings available, what used to be a meaningless token swept up by the day’s breakaway has now become the race-within-a-race of a green jersey competition in which Peter Sagan‘s lead has concertinaed from seemingly insurmountable to potentially vulnerable.

Greipel has sacrificed his green jersey chances for stage wins (image courtesy of Lotto-Belisol)

But even here, with the sprinters often racing for a valuable 10 or 11 points from out of the chasing peloton, the Conservation of Energy still applies. The vast majority of these sprints have been won by a rider – usually Mark Cavendish – racing at no more than 95% with the aim of winning with the least amount of energy, in order to save something for the end-of-stage sprint. It’s often been a bit like watching a dance rehearsal where everyone steps through their moves at half-speed.

In some cases, riders have taken this to the extreme, eschewing the intermediate sprint altogether to focus on conserving their finishing burst. In effect, this means sacrificing green jersey aspirations for a greater chance at stage wins. So while Cavendish, Matt Goss and Sagan have contested every sprint, Andre Greipel, Tyler Farrar and many of the other fast men have kept their powder dry for the finish. Doing so certainly hasn’t harmed Greipel, who took back-to-back victories on stages four and five, and might well have made it three in a row in Metz yesterday had he not dislocated his shoulder in an early crash.

It has added a new dimension to sprint tactics, giving us a clear split between those who want the jersey and those who seek only the glory of stage wins as riders have had to nail their colours to the (green) mast. The fact that riders have to compromise one option to pursue the other is all down to the need to conserve that 1% extra energy that makes the difference between a great jump in the closing metres of a sprint and one which makes no impression whatsoever.

Doing a McEwen

I’m fascinated by the way some riders are obviously so much better at finding ways to conserve their energy than others, who look positively wasteful by comparison. In his autobiography One Way Road, three-time green jersey winner (and now Orica-GreenEDGE sprint coach) Robbie McEwen describes his almost obsessive focus on saving small scraps of energy that he could use to his advantage in the final bunch sprint. These ranged from always taking the best possible line through corners – something a lot of riders are quite lackadaisical about – to ‘surfing the peloton’ (using the energy of the bunch to allow him to ease smoothly up towards the front with minimal effort), to what Kitty calls ‘doing a McEwen’: cruising up to the front of the pack at the foot of a mountain, and then slowly drifting down to the back as the climb progresses, thereby minimising effort.

Is Farrar wasteful with his energy? (image courtesy of Danielle Haex)

On the flat stages, it’s noticeable that Cavendish is the heir apparent to McEwen. Of all the sprinters, his ability to read the shifting sands of the peloton and put himself onto the right wheel at the right moment with the minimum energy expenditure is arguably the best of the bunch.

Some riders possess that instinct, others don’t. For instance, I’ve long been of the opinion that Tyler Farrar is a talented sprinter but also one who is slightly wasteful with his energy. Whereas Cavendish typically cruises about a third of the way back in the peloton before decisively ghosting his way to the front when he needs to, Farrar seems to waste effort drifting aimlessly backwards and forwards – just watch how he’s often caught out by crashes in the bunch that others always seem to avoid, which must surely cost him in some small way at the end of the stage. Whether that is the result of too much nervous energy or not enough instinct is unclear.

I’m not sure who else might one day replace the departed Robbie as the king of ‘doing a McEwen’ in the mountains. But I’ll be watching out on this afternoon’s climbs to see which sprinters keep popping up at the front of the bunch in the foothills, before slipping gently back down again. I’ll probably be conserving my energy by sitting back and relaxing with a beer while doing it …

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Link: Tour de France official website