Something that the bike industry doesn't seem to consider is that the forces involved with a heavier rider are much higher compared to a lighter rider, hence the braking comment above. 90kg at the same speed compared to 60kg creates significantly higher forces on tires, wheels, frame stiffness and fork stiffness, yet you don't really see companies making stronger/stiffer bikes for bigger riders, and both lighter and heavier riders ride the same wheels and tires at mostly the same pressures... Smaller riders also sit more IN the bike compared to larger riders who sit more ON the bike relatively speaking...