The running backpack is typically a bit tighter on the body, because you usually move more when you run than when you cycle. The rucksack receives stronger impulses from the jolts of the running movement. For this reason, running backpacks are often anatomically shaped so that they nestle tightly against the back. In the case of bicycle backpacks, however, there is often a belt system that allows a precise fit. In this case it is possible to walk with the bike backpack on your back. On average, the bike backpacks are heavier than the running backpacks, but they are often larger so that you can fit more in them. These points should also be considered if you want to exchange the two models.