The standard 0.8g/kg per day RDA was set for sedentary adults. It is not the right number for trained endurance cyclists. Current sports-nutrition consensus puts the target for cyclists at 1.6-2.2g/kg of bodyweight per day — roughly double the RDA. For a 75kg cyclist, that's 120-165g per day, ideally spread across 4-5 meals at 25-40g each.
Why so much more? Endurance training breaks down muscle protein at higher rates than sedentary life — particularly during long rides and during periods of energy deficit (which most amateur cyclists are in more often than they realise). Without enough dietary protein, the body cannibalises muscle tissue to repair the damage, which slowly erodes both performance and metabolic health.
Distribution matters as much as total. Eating 150g of protein in two meals doesn't have the same effect as 30g in five meals — muscle protein synthesis is maximised at around 0.4g/kg per meal, after which the additional protein contributes less to recovery. Practically: aim for 25-40g per meal, with the post-ride meal containing the largest dose.
Two specific cases. Masters cyclists: target the upper end (1.8-2.2g/kg) because of 'anabolic resistance' — older muscle responds more slowly to protein, so more is needed to drive the same response. Cyclists in a calorie deficit (race-weight prep): protein needs go up further, not down — typically 2.0-2.4g/kg — to preserve muscle while losing fat. The Roadman protein guide breaks both cases down with specific food examples.