there are weight limits so it's not about that

. it's about their capacity to push, just like they do in rugby and football/ strength of legs, like sprinters in track
Here are the max weight limits and the minimum limits as well (minimum because it would be dangerous if the bob was too light)
- 4-Man Bobsleigh:
- Maximum combined weight (Sled + Crew + Gear): 630 kg (1,389 lbs)
- Minimum empty sled weight: 210 kg (463 lbs)
- Implied max crew capacity: 420 kg (average of 105 kg per athlete)
- 2-Man Bobsleigh:
- Maximum combined weight (Sled + Crew + Gear): 390 kg (860 lbs)
- Minimum empty sled weight: 170 kg (375 lbs)
- Implied max crew capacity: 220 kg
- 2-Woman Bobsleigh:
- Maximum combined weight (Sled + Crew + Gear): 330 kg (728 lbs)
- Minimum empty sled weight: 165 kg (364 lbs)
- Implied max crew capacity: 165 k