It’s easier to cycle behind someone else.
That’s it. That’s cycling. Pretty much every tactic revolves around that one simple fact. The reason for this is wind resistance. Road bike tyres are narrow, so there isn’t much rolling resistance. The main thing slowing you down is the air. This may seem unlikely, but compare your speed when cycling into the wind to when it’s at your back. Wind is just air. Air matters.
Cycling behind someone else negates wind resistance to a massive extent. This is known as ‘drafting’. The faster you’re going, the greater the wind resistance, so the more benefit there is to being behind someone else. The corollary of this is that if you’re going to win a bike race, the best opportunity to get in front of everyone else is when the benefits of drafting are least noticeable – when you’re going slowest.
On a hill, the pace drops significantly. The main thing slowing you down is gravity and the effects of gravity are the same whether there’s someone in front of you or not. This is why most of the best riders are pretty damn good at cycling uphill.
There are nuances to all of this, but really the whole sport revolves around that one simple truth: it’s easier to cycle behind someone else.
Further reading
You may now like to know which bike races actually matter.