All the bikes in Mario Kart 8 only have one fork, so that the wheel can flip over during anti-gravity mode.
“One fork” might be a bit of a misnomer. It’s more like one tine of the fork.
Ok, let’s back up and go over a little bit of bike anatomy. At the front and back of the bike where the wheel connects to the frame is called a fork. It’s called that since the frame seems to “fork” onto either side of the wheel so the axle can go through it and connect to the frame. With us so far? Good.
In Mario Kart 8, they introduced a fancy new “anti-gravity” drive mode that causes everyone to flip over their tires and start hovering. That’s not a problem on cars since the wheels are connected at the end of the axle. But on a bike that’s an issue. They’re connected in the middle of the axle, which means that in order for it to flip down some other weird transformation would have to happen, like the axle snapping in half or something.
Rather than overcomplicate matters, Nintendo picked a much simpler solution. They made Mario Kart 8’s bikes mimic the same wheel arrangement as its cars by making the bike’s wheel only connect at the end of the axle, and for that axle to only connect to a single extension of the fork rather than the twin extensions you’d see on a real-life bike.
So far there’s one exception to this innovative design, and that’s on the recently released Master Cycle Zero from the Breath of the Wild update. This bike features the twin-tined fork that you’ve come to expect from most bikes, but there’s a twist.
If you look closely, you’ll note that the axle doesn’t actually extend to both sides of the fork. Instead, it only goes as far as one end of the form, with the other just sort of hanging out there. When it comes time to go anti-grav, the wheel flips over, and then the unconnected side of the fork appears as an additional support for the anti-grav tire… thing…