The Tour de France is one of the oldest major sporting events in the world, and with such heritage comes some unwritten rules and customs which may seem odd to the uninitiated. 

These rules may be commonplace at the Tour de France, but they can also apply to other races, not just the big Grand Tours. Here are some of the more prominent ones that you're likely to notice whilst watching the race:

Leader's First

The race leader's team has responsibility for being at the front of the peloton at the start of the race. They are responsible for marshalling the peloton until the day's breakaway has been formed and the initial pace-setting, with other teams joining them later on. 

This isn't always the case but on most stages you will see the race leader and his team at or near the front for the race starts, unless the start is particularly unusual or a large number of riders are attempting to breakaway.

Respect The Jersey

It's bad form the attack the race leader when he suffers a mechanical problem or stops to take a nature break, and you will often see riders slowing or waiting for the jersey should there be a problem. 

This 'rule' has been controversial in recent years and ignored in the Giro d'Italia when the Vincenzo Nibali and Nairo Quintana attacked leader Tom Dumoulin at the foot of the final climb when he needed to stop for the toilet. It recently came into the discussion once again in this Tour when Fabio Aru attacked Chris Froome when he had a mechanical problem on Stage 9.

This one is often discussed as having a fine line between a sportsman-like agreement and preventing the race from happening in its natural way, but you will rarely see riders attacking a race leader who's suffered misfortune outside of their control.

The Sticky Bottle/Bumper Draft

technically illegal way of getting back to the peloton after a puncture or receiving medical aid at the team car, the commissaire often turn a blind eye to this practice.

The sticky bottle is when a rider will reach for a bottle being held out of the team car, grab on to the bottle and hold it whilst the car accelerates a little before letting go and taking the bottle. 

The bumper draft is similarly where a rider will get right behind the team car as it accelerates through the cars back to the peloton.

Both of these are illegal but, providing they aren't abused, are only used for a short time, and have no impact on the end of the race the commissaires usually turn a blind eye; the most they will do is beep their horns at the rider/team car or issue a small fine.

When Nature Calls

With riders spending nearly 5 hours on the bike each day - sometimes more - it's natural that they will need to take a nature break at some point in the stage, especially with all the fluids and food they take on.

Often riders will discuss this in the peloton and decide to have a natural break, with large groups stopping together before rejoining the peloton with relative ease in their large numbers. 

This is especially the case with GC riders and their teams who will agree to stop during the race to prevent anyone needing it later on at a crucial moment.

When this happens you will see them lined up at the side of the road like they're at one large urinal; one foot still clipped into the pedals ready to jump back on at a second's notice.

The Gruppeto

Also known as the 'Autobus' this is the group of sprinters and riders who are struggling in the mountains that forms at the rear of the race. When the race goes ahead and the cameras focus on the GC battles and fight for the stage, the grupetto is only concerned with getting to the end inside the time limit.

There are masters in the peloton who can work out what the time limit is likely to be based on the stage distance and the average pace of the race, and consequently the time they need to complete the stage in to stay in the race. 

Once they know this then they can ride at this pace and come in under the time limit without having expended a lot of energy trying to ride their own race. The grupetto often features the main sprinters and several teammates, unless their team has a GC rider, who will help them get to the end.