It wouldn’t be the Tour de France unless someone mentioned the ‘unwritten rules’. Ullrich and Armstrong. Contador and Schleck. Coppi and Bartali. Aru and Froome.

Altogether now, you know how this goes: you don’t attack the yellow jersey if he has a mechanical. Or if he stops for a pee. Or if he crashes. Or if he’s held up by someone else’s crash. Or if you have any other reason to believe he might not like it.

>>> 11 Tour de France rules you probably didn’t know

Not that the rules are consistently observed. Even when they have been, it’s often difficult not to be cynical. The ‘don’t attack the leader’ rule has, as often as not, only been observed after someone did attack under the sort of circumstance described but failed to make it stick.

At that point most riders have simply recast their physical weakness as moral purity, and claimed that despite the throbbing veins in their temples they were waiting. At 40kph. Up a hill. Out of the saddle.

It sounds deceitful, and it is, but if you ever looked over your sneaky shoulder and saw the wrathful form of, say, Lance Armstrong fuelled by closely focused hatred bearing down on you, you’d do the same.

Whether the rules are obeyed or not doesn’t matter a jot. That’s not what they’re there for. They’re there because nothing makes you feel part of a club like an unwritten rule. It’s their unwritten-ness that appeals, not their rule-ness.

Part of the joy of the unwritten rule is that we can use it to un-write a rule that actually is written down. The sticky bottle is the outstanding example.

Sticky bottles: Against the rules (but not really) (Watson)

There is nothing about a rider and a team manager grimly battling for possession of a bottle being held out of a car window at 50kph that isn’t against almost every rule in the book.

But who doesn’t get a frisson of satisfaction from explaining to a lay observer that this is a traditional part of cycling’s rule-bending?

There is no such thing as a rule in pro cycling, just a starting point for negotiations. For instance, you may not punch another rider. Not ever. Oh, unless a) it’s the Tour de France, b) you’re French and c) the other big-name French sprinter missed the time cut two days earlier. (See entries for Nacer Bouhanni passim.)

All of this sort of thing gives us a worldliness that means we can lord it over other, more Corinthian endeavours, like golf and crown-green bowling, and aligns us with bare-knuckle boxing and no-holds-barred alligator wrestling. Or so we like to think.

In the amateur ranks, the same instinct to be an insider takes a different form.

With no yellow jersey and no patron to deal with, the tussles are over things as epoch-defining as whether you put the arms of your sunglasses inside or outside the straps of your helmet. You put them outside, by the way. I don’t know why.

A pity, when there are so many urgently needed rules that are not only unwritten but non-existent. “Replace your shorts before they wear so thin I can see the crack of your backside through them,” or, “If you have to fart, do it quietly at the back of the group.”

The problem is that people seem to find it almost impossible to resist the temptation to write down the unwritten rules. At which point they vanish, in a puff of logic, and suddenly any fool who can read knows as much as those of us who had to find out the hard way.

The opportunities for patronising explanation have been reduced to almost zero. Newbies don’t have to do what we did, and spend the first two years of their cycling careers wondering why people were looking at them with barely suppressed mirth. It is no fun at all.

Not that it’s meant to be fun. That’s another rule. Don’t tell me you didn’t know.