As a lifelong athlete, I concur this.
Stretching before the ride keeps the muscle supple and strong but stretching after is very important if one is wanting to keep that strength and suppleness for a very long time and to avoid any kind of injury.
Most of the injuries I have had can be traced back to poor warm-ups and poor after game activity.
I make it a habit to take a warm water shower after any ride that exceeds 25 miles.
Another thing that is crucial is, right kind of hydration.