Monstrosity? We call it a “Chopper”!
(No, really. Go ask a bike mechanic if they have any sweet choppers for sale.)
Though, yeah, you might have a point.
I (as a biker and a cata player too) think too that bikes in cata does drains too much stamina and also is too slow.
Do you guys know what seems really OP IMHO?
- A pair of rollerskates
- A wheelbarrow
You “walk” (about 100 moving cost) around with 275 volume to use to what seems the same speed and stamina cost as walking, you can RUN really quick (about half movement cost), instant “acceleration” to 32Km/h (isn’t that the speed of running at ~50 moving cost?) instant stop, great maneuverability…
Bike has what? 150 volume? I barely can “walk” they, 16km/h (same speed as 100 moving cost, zombies walking), draining all the stamina, poor acceleration, stop, maneuver, etc…
Off course, I know rollerskates/blades, are poor in bad terrain, but you got the point. Come on, “running” a heavy wheelbarrow full of loot and guns, 32km/h with rollerskates is better than a bike?
Also, this combo (wheelbarrow+rollerskates) off course make you loot neighborhood very quickly, you can go inside houses, bikes cant.
Sorry my english, also I know there is “miss labeling” about the movement costs, but I think you guys understand what is my point.
By any means, I’m profoundly grateful you developer guys are always trying to balance the game. I’m not criticizing or something, just my non-primary-english-language-biker-injusticed-idiotic way to speak. 
They are OP. Wheelbarrows have no balance check, and arent exactly made sturdy enough to prevent tipping in a combat situation.
Shopping carts are very convenient. I dont use them nearly as much as I used to, but if you replace the basket/bin of these 1 tile vehicles with a floor trunk you gain 75 volume and can use it to completely avoid acid. Although you cant use it for kiting zombies if you do that . . .