@nugger @ACL9000
Dirtbike is just small unstable car. Unlike horses you can't team a dirtbike to increase it's pulling capacity (at least I've never seen anyone try). In order to haul more (and people will ALWAYS be maximizing the amount they haul, it's simply inevitable) you'll have to build a bigger, more stable dirtbike, plus doing so is more efficient anyways. So make the engine bigger and give it an extra wheel. Keep developing the dirtbike and you'll eventually just end up with cars again. Probably different than modern cars due to their different development path, but cars non the less.