Tour de France 2021
40 Achievements
1,000
Xbox One
Xbox Series
Rainbow
Win the World Championship with your Pro Leader (Pro Leader mode).
30
14.11%
How to unlock the Rainbow achievement in Tour de France 2021 - Definitive Guide
Easty
Go to Pro Leader mode, select Amateur difficulty and Database #1 (if you followed the step 1 of the roadmap to modify everything needed). Create your team (country doesn't matter), then create your racer. You want to make him a Sprinter and most importantly select Norway as his country. This is because your racer will have a ~63 overall rating, and without modifying the other Norwegian racers you will never get selected for the World Championship. As the Norwegian racers are the fewest in this game, it's the fastest option.
For the first season, you will only get access to 3 races, but it doesn't matter anyway since you want to simulate every single thing. The only race that you need to worry now is the World Championships at the end of the season. If it's a Green icon race, play it (don't simulate), if not move to the next season and repeat until you get the Green icon race.
When you get the Green icon race, play it and as soon as the race starts press
and 
to fast forward. You can also press on another racer of your team and select Protect "your racers name", so he will be less tired at the end. Do not worry about the other racers, they will all end in the same group near the end.
Now when you reach the 10 last kms of the race, make a save. And now is the trickiest part of the game, you need to actually play and win this race. So try to get to the top of the group but don't race too hard or you'll lose too much stamina for the sprint at the end. When you reach the last 3 kms you want to go a bit faster but don't press
too much, keep an eye on your blue and red bars you don't want them to deplete now, just take a small advance from the other racers.
Make another save, and at the last kilometer, everyone should start sprinting but as you modified all the good sprinters in the game, none of them should be fast enough to catch you (if you didn't, it's still possible but will take a lot of retries since there will always be one cheated sprinter that goes way too fast). So sprint your way by pressing and hope no one catches you. If they do, quit the race and reload your last save and try again. It can take some retries, if you struggle too much, reload your save at 10kms and try to take a higher lead and/or save more stamina.
For the first season, you will only get access to 3 races, but it doesn't matter anyway since you want to simulate every single thing. The only race that you need to worry now is the World Championships at the end of the season. If it's a Green icon race, play it (don't simulate), if not move to the next season and repeat until you get the Green icon race.
When you get the Green icon race, play it and as soon as the race starts press
and to fast forward. You can also press on another racer of your team and select Protect "your racers name", so he will be less tired at the end. Do not worry about the other racers, they will all end in the same group near the end.Now when you reach the 10 last kms of the race, make a save. And now is the trickiest part of the game, you need to actually play and win this race. So try to get to the top of the group but don't race too hard or you'll lose too much stamina for the sprint at the end. When you reach the last 3 kms you want to go a bit faster but don't press
too much, keep an eye on your blue and red bars you don't want them to deplete now, just take a small advance from the other racers.Make another save, and at the last kilometer, everyone should start sprinting but as you modified all the good sprinters in the game, none of them should be fast enough to catch you (if you didn't, it's still possible but will take a lot of retries since there will always be one cheated sprinter that goes way too fast). So sprint your way by pressing
and hope no one catches you. If they do, quit the race and reload your last save and try again. It can take some retries, if you struggle too much, reload your save at 10kms and try to take a higher lead and/or save more stamina.