The track side is relatively easy to explain: There are relatively few countries that take the track seriously. In the traditional cycling nations, talent bypasses the track and goes to the road. In the UK, for 10-15 years now, all the talent goes to the velodrome in Manchester. To complement all this, since the 2012 OGs were awarded to London (mid 2005) there has been a huge amount of money directed towards likely medal-winning sports (track cycling, rowing, sailing, equestrianism).
GB has also targeted the "timed" events, where tiny fractions make all the difference, as a timed event is essentially "cycling by numbers" rather than tactical. The cash that the GB set up has makes it that much easier to cover all the angles that might arise. For example, GB could trial more types of material for skinsuits than others, to find the most aerodynamic, and experiment with bike design, simply because they have more cash for salaries and experimentation.
http://www.dailymail.co.uk/sport/ol...es-using-drugs-claims-disgraced-supplier.html
Note that Conte's 60% is an
average estimate. Of that 40%, I assume 90% consists of athletes who didn't compete for the medals. Perhaps 10% of clean athletes on the podium.
It also helped that on the mens' side, in the sprint and the TP, the GB opposition was way down performance-wise on what they'd achieved earlier in the season.
On the road, the only unavoidable eyebrow-raiser amongst the Brits is Froome. His transformation from being out of contract to the Vuelta podium in less than a month just cannot really be explained with a straight face, even by committed Sky/Froome fans.
All other performances in GB/Sky's success are plausible (ish) in isolation, though in combination, they take a leap of faith to accept.