The Tour de France, which finishes in Paris next weekend, attracts more than 10 million spectators to line its near 3,500km route, uniquely comprehensive press coverage for the sport and a TV and online audience estimated to be in the billions. Yet only a tiny fraction of those watching will have the first clue as to what is actually going on.

Yes, there are obviously winners of the 21 stages, and an overall champion is crowned when they reach the Champs-Élysées. But in a peloton of 180 riders, operating in a seemingly chaotic working environment best described as like being inside a washing machine, very few are attempting to win. The vast majority are implementing a dizzyingly fluid set of agendas and allegiances that can combine – often in the same rider in the same race – team and personal ambitions, altruism and blatant commercialism, high courage and low cunning. In what is quite a brave admission for a cycling journalist, Peter Cossins admits early on in this breezy, enlightening book that even for someone who has reported on the sport for quarter of a century, what actually happens between flag and finish can often be close to “incomprehensible”.

So Cossins began to look at races with a new eye, moving his focus away from the winners to instead observe “the constantly evolving and frequently quite exquisite tactical puzzles that every bike race sets”. He comes across comparisons with poker, and bluffing and playing your cards astutely. But he takes as his starting point the idea that bike racing is analogous to “chess at 150 heartbeats a minute”. (For context, Chris Froome, as we were recently reminded during his travails about his inhaler, has a resting heart rate of about 30bpm.) This concept of cycling as requiring sharpness of both body and mind is nothing new. The first significant organised bike race, from Paris to Rouen in 1869, was won by James Moore, who took a straightforward approach: “As soon as the signal was given, I pressed on the pedals with all my might.” But by the 1891 Bordeaux-Paris race, riders were already drafting – using other riders to protect themselves from the wind and thus save considerable amounts of energy. In 1894, Henri Desgrange, later to be known as “father of the Tour de France”, called his influential training manual La Tête et les Jambs (The Head and the Legs) and declared: “An intelligent man always beats a brute.”

Cossins traces an ​arc to today’s stars, whose husbanding of energy produces three-week races won by only seconds

Cossins traces a long arc from the pioneer 19th-century racers who started out at a sprint and only slowed down as exhaustion struck, resulting in gaps of hours between riders, to today’s stars whose obsessive husbanding of energy results in three-week races being won by a matter of seconds. Along the way he pays tribute to the great riders and their tactical innovations: raising the tempo on a climb, deploying teammates to attack rivals, raising tempo approaching a climb, attacking on descents. Fausto Coppi, Eddy Merckx, Bernard Hinault, Miguel Induráin and, most recently, Chris Froome and Team Sky have all applied their tweaks to a story that is more evolution than revolution.

The takeaway message is that the strongest riders win not just because of their talents, but because of their ability to adapt tactics to maximise their advantages as well. Yet there is scope for lesser riders to have their moments, too. Cossins dissects the tactical thinking behind sprinting and climbing, dealing with the wind and life at the back of a race in the gruppetto. Doping and other dark deeds are also covered. But the star of the book emerges in his section on the breakaway. A feature of most races, the breakaway looks like, and often is, simply a way for a small team to get some TV exposure or a speculative punt by riders who feel strong on the day. But when a breakaway includes Belgian strongman Thomas De Gendt, it can become a much richer and more complex affair.

De Gendt talks Cossins through the 19th stage of last year’s Vuelta a España, during which he delivered a masterclass in his chosen art. He combined years of experience and detailed intelligence gathering – about courses, the state of a race, the strengths of other riders – with rapid decision-making on the road to pull off a famous victory. Too often, Cossins says, a breakaway success is seen as a matter of luck on a day when the chasing peloton was either incompetent or uninterested in catching them. De Gendt’s “craft and knowhow … illustrates the falseness of that assumption”. (Not that tactical nous is everything: De Gendt also appears to possess the durable power of a tractor engine and a capacity to soak up pain that would make the Marquis de Sade wince. Head and legs!)

Cossins suggests the best place to observe tactics in action today is in women’s racing. While the levels of skill and professionalism have vastly improved in recent years, budgets haven’t caught up, resulting in small teams that can’t afford the specialisation of the men’s sport. This has prompted riders to acquire wide skill sets and an ability to constantly adapt their style to different modes of racing.

When looking back on his year watching the process of a race, rather than just its outcome, Cossins says he not only fell back in love with the sport, but also discovered the “full scope of its beauty for the first time”. To add to the poker and chess analogies, there is also an appropriate old literary adage in the sport: a good bike race might be an interesting whodunit, but it might be an even more interesting howdunnit.

• Full Gas is published by Yellow Jersey. To order a copy for £14.44 (RRP £16.99) go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.