Chris Froome remains focused in the eye of the storm at the Tour de France

If Chris Froome began the Tour de France as one of four favourites for the general classification, it now feels as if he is on his own as public enemy number one.

The French police have grown in numbers around Sky's leader. Amid the usual crowd of fans and journalists, four to five armed officers have stood guard, alert for would-be troublemakers over the last three days.

The protection is in response to attacks on the team. A fan threw urine on Froome yesterday, some spat on Luke Rowe and Richie Porte, and one punched Porte on Tuesday en route to his second place behind Froome at La Pierre-Saint-Martin.

"I'm not afraid," Froome said after the 15th stage to Valance today. "I'm focused on the bike race. I've got a job to do here."

In the heat of Mende on Sunday morning, Froome, Porte and other team-mates rode on their trainers outside Sky's black bus. Besides the Tour de France workers in green shirts, police officers with pistols at their waist scanned the crowd.

A similar scene was found at the finish 183 kilometres later.

"If you look at any big sporting event – you look at tennis, any big event, football – there are police all over those events, especially when fans start getting more involved in the event than they should do," Froome said.

"I don't think it's that bizarre when there are police around in the morning when we're warming up or leaving the buses."

The beauty of cycling, however, is that the sport is played out on open roads and fans are close. Sky's riders may feel safer at the starts and finishes, but between, nothing protects them from people who would potentially cause harm.

"It's not for me to say what security is needed. The organisation puts on the event. It's their responsibility to keep the riders safe," Froome added. "From the riders' point of view, we just want a safe race and all the athletes are looked after in an appropriate manner."

Froome repeated that it was a minority of people causing trouble on the roads. Today, he explained that the "atmosphere on the road was fantastic".

"[The trouble is] certainly not going to sour the yellow jersey if I do make it to Paris in the yellow jersey,” he said. “This is something myself and my team have worked extremely hard for and nothing's going to change how amazing it would be to win this if we do get that far."