Tour de France Stage 7 Preview with Chris Boardman
Tour de France Stage 6 Preview with Chris Boardman
The hidden science behind the bottle-smash trick? Cavitation! Check out this instructional video. If you have a home-built vacuum water bottle, you can easily see the violent implosions as they happen.
Cavitation means that cavities or bubbles are forming in the liquid that we're pumping. These cavities form at the low pressure or suction side of the pump, causing several things to happen all at once:
* The cavities or bubbles will collapse when they pass into the higher regions of pressure, causing noise, vibration, and damage to many of the components.
* We experience a loss in capacity.
* The pump can no longer build the same head (pressure)
* The pump's efficiency drops.
The cavities form for five basic reasons and it's common practice to lump all of them into the general classification of cavitation. This is an error because we'll learn that to correct each of these conditions, we must understand why they occur and how to fix them. Here they are in no particular order :
* Air ingestion (Not really cavitation, but has similar symptoms)
* Internal recirculation
* Flow turbulence
* The Vane Passing Syndrome
Briton Mark Cavendish won the third stage of the Tour de France as seven-times champion Lance Armstrong climbed up to third overall in the standings at La Grande Motte.Cavendish, who also won the stage on Sunday, outsprinted Norway's Thor Hushovd after a 196.5km trek from Marseille with France's Cyril Lemoine coming home third.Swiss Fabian Cancellara of the Saxo Bank team retained the overall leader's yellow jersey and now leads German Tony Martin and American Armstrong by 33 and 40 seconds respectively.Favourite Alberto Contador, who was trapped behind after a sharp acceleration by Cavendish's Columbia-HTC team by the end of the stage, dropped to fourth overall, 59 seconds off the pace.With the peloton gradually closing down a four-man breakaway composed of Samuel Dumoulin (Cofidis), Ruben Perez (Euskaltel), Maxime Bouet (Agritubel) and Koen de Kort (Skil-Shimano), a bunch sprint finish seemed in store.But the peloton split into two parts some 40km from the finish after a sudden acceleration by Columbia-HTC that surprised almost all the favourites, including Contador.Among the top contenders, only Armstrong, back in the saddle after 3 1/2 years in retirement, was in the front group of some 28 riders who caught the four early fugitives.Columbia, with no fewer than eight men inside the lead group, instantly pulled as hard as they could, and were joined by five of Skil-Shimano's riders, along with the Milram duo of Linus Gerdemann and Fabian Wegmann.Armstrong did not help Columbia widen the gap, staying in the middle of the small pack with team mates Haimar Zubeldia and Yaroslav Popovych -- at first.But with 15km remaining after discussions with team boss Johan Bruyneel, Popovych and Zubeldia started to work.Seeing Armstrong and Cancellara further up the road, Cadel Evans' Silence-Lotto team, Andy Schleck's Saxo Bank squad and Christian Vande Velde's Garmin team took turns to try to reel the leaders back in, but they lacked the organisation of Columbia's well-oiled machine.As the finish neared so the gap grew and the Columbia train began to move into position.Bert Grabsch and George Hincapie, both of whom had given their all on the front for a large part of the crucial final 30 kilometres moved aside, and Mark Renshaw hit the front as they entered the final straight.With Hushovd and Cancellara in contention, victory was by no means a formality for Cavendish, though when he moved out of the slipstream of Renshaw with 200 metres to go and surged for the line, it was clear Hushovd did not have the power to match him.The Norwegian rolled in second with Dumoulin claiming a well-deserved fourth place, having managed to stay with the relentless pace of the lead group, despite having ridden out front for over 160 kilometres in the breakaway.Martin and Armstrong were the day's big winners as the gap between the two groups reached 41 seconds on the finish line.The general classification will receive a more significant shake-up in Tuesday's fourth stage, a 39-kilometre team time-trial around Montpellier
Astana take team time-trialAstana's all-star team showed their strength to win the team time-trial in stage four of the Tour de France at Montpellier, as Fabian Cancellara defended his yellow jersey from Lance Armstrong by less than a second,Chasing Garmin-Slipstream's time of 46'47" on a testing, technical course, Alberto Contador led Astana across the finish line 18 seconds up on the American team, and 40 seconds ahead of Cancellara's Saxo Bank team.The Swiss specialist kept his yellow jersey despite being level on time with Armstrong on the general classification, denying the American a fairytale return to the Tour.The relentless pace of the Garmin team put them in a difficult position as they lost four of their riders over the first half of the course, but their five remaining time-triallists par excellence - Bradley Wiggins, David Millar, David Zabriskie, Christian Vande Velde and Ryder Hesjedal - produced a superb display of power that came close to securing them a stage win.The Saxo Bank team of the Schleck brothers was third, and in the end it may have been a huge effort on the front of their train over the last kilometre from Cancellara himself that allowed him to keep his yellow jersey, after intermediate splits had previously suggested the advantage lay with Armstrong.The Columbia team, who had upstaged Garmin in the team time-trial at the Giro d'Italia this year, were off the pace from the start, and they finished in fifth place, 59 seconds off the time of Astana, with Liquigas sneaking in ahead of them by a second in fourth.The two big losers of the day among the general classification contenders were Cadel Evans and Denis Menchov.Evans's Silence-Lotto team were a disappointing 13th, 2'35" off the pace, while Menchov, known for his lack of confidence in bike-handling, fell early on. Though the big Russian recovered well, his team could manage no better than 11th position, 2'20" back.Carlos Sastre's Cervelo team were never likely to challenge the likes of Astana and Saxo Bank, though managed to limit their losses to a respectable 1'37" on the Kazakh-backed outfit.The lack of time bonuses makes an Armstrong challenge for the yellow jersey on stage 5 unlikely, though Friday's stage to Andorra-Arcalis is likely to see an attack.