Pain and posture
Tight, shortened hamstrings are one of the biggest culprits in postural dysfunction, recurrent back pain and reduced speed and agility on the sports field. For cycling in particular, hamstring range needs to be maintained so you can sit comfortably on the bike and avoid falling too far into a posterior tilt.
The connection between tight hamstrings and lower back pain is well-known and confirmed by multiple studies. Your hamstrings originate from the ischial tuberosity (the sit bone) and insert below the knee. Their function is to extend the hip and flex the knee. They are powerful and explosive. On the bike, they assist us in powering into a hip extension during the downstroke and then pulling up on the cleat during the upstroke phase of the pedal cycle.