The Tour de France - the biggest race in cycling - is getting underway in Germany.
The competition goes on for 23 days, with nearly 200 cyclists from all over the world taking on the 2,000 mile challenge.
Here are the Brits to look out for...
Chris Froome is not only top of the Brits, he's the Tour's reigning champion and favourite to win again this year.
He has won the race three times already: in 2013, 2015 and 2016.
Now he's hoping to add 2017 to his list.
He's not had the best run-up to this year's event though - he finished fourth in the traditional warm-up race, the Criterium du Dauphine, so he'll be hoping to pull it out of the bag for the real thing.
Mark Cavendish is most famous for his daring sprint finishes, which have brought him lots of success in previous years of the Tour.
It's not just the overall winner who matters in the Tour de France - each stage of the race has a winner as well, and that's where Cavendish does best.
He's had an incredible 30 stage wins, which is just four fewer than the all-time record holder - Eddy Merckx.
The flat roads on this year's tour will suit Cavendish's style, but he's also suffered from illness this year which might have affected how well prepared he is for the 23-day challenge.
2017 is Geraint Thomas's seventh Tour de France, and he rides in support of Chris Froome - helping to push him to victory.
Thomas wasn't actually planning to ride in the Tour this year. He was concentrating on another competition, called the Giro D'Italia instead.
But he had to withdraw from that race after a collision with a parked motorbike, so he's changed his focus to the Tour de France instead.
Simon Yates is just 24 years old, and his twin brother won the White Jersey for being the best young rider on last year's Tour.
Yates specialises in climbing, so the steep mountain roads in the Tour de France suit him well and he'll be hoping to have similar success to his brother!
Steve Cummings has raced in the Tour de France four times before, and has had two stage wins.
It wasn't clear if he would be part of the 2017 Tour, after he got injured in a crash earlier this year.
But after a great week at the British National Road Championships, he was finally confirmed to take part.
2017 is Dan McLay's second tour.
He's a sprinter, and won an impressive four top-ten finishes during his first Tour de France in 2016.
He came 170th overall in 2016, but being a fast sprinter, like Mark Cavendish, could put him in with a chance of a stage win.
Luke Rowe is a 'domestique' rider, which means that he works for the benefit of the team, rather than trying to win the race himself.
He's best known for helping teammate Chris Froome who he's supported on both of his last two Tour victories.
Ben Swift is another sprinter appearing for his second Tour de France in 2017.
As well as having speed, he's also known for getting over lumps and bumps on the road better than most sprinters, which is a useful skill on the Tour!
2017 is Scott Thwaites' first appearance at the Tour de France.
As well as getting through the race himself, he's hoping to help Mark Cavendish in the battle for stage wins.