My courier was walking up to the Mojave outpost when I saw a truck full of nearly spotless motorcycles and I thought it odd that with all the mechanics and expert scientists they couldn't fix a bike even with seven others as spare parts, that and since they were in a truck there's a good chance they were brand new and had never been driven. I mean ghouls have launched rockets, the Enclave and the NCR can operate nuclear powered VTOLs, in one of the older games you get a car and in FO3 you fix a giant bloody robot but all of these bikes around the wasteland are beyond repair.
And considering the enormous tactical advantage it affords people I'm surprised it isn't a bigger priority.
Also how badass would the Brotherhhod look if thy just rode around on those 'steeds of steel'
If that's not an option why not just make bicycles, they aren't that fast but it's way quicker than walking and you can carry more things.