Why is it so difficult to drive backward in a straight line?
In: Engineering
So many miss an ELI5 explanation.
Everyone has a bike, right? The forks of the bike are not straight, they curve forward a bit.
So, the neck of the bike where the forks slide into, draw a vertical line downward from that. We will call that true vertical.
Now, the forks are bent, so draw another line from the point where they go in the neck, to the ends, where the tire bolts on. It should be a diagonal line from true vertical.
Now imagine that area on the ground, we will call it a patch. It is an area in front of true vertical in a positive direction.
Now for the fuck heads. What happened when you were a kid and turned your handlebars backwards and tried to ride? You fell on your ass, right? That is because now the patch goes in reverse and is a negative patch.
Your car has true vertical and a positive patch as well by using ball joins on the steering arms. It is called caster and used to keep the car going straight. When you drive backwards, you now have negative caster, just like on your bike when turning the handlebars around.
On a side note, anyone that jacked up their care back in the day, had reduced steering. Why? Are you raise the rear, the positive caster shrinks (among other things).
Because people dont understand that when the steering wheel is right side up and flat, you drive straight.
Anyone note that your direction of adjustments is reversed? it’s like driving a forklift, with the directional change happening at the back rather than the front.
If you are turning your head too look behind you it’s very likely you’re activating your asymmetrical tonic neck reflex which causes elbow extension on the arm where your head is pointing and elbow flexion on the opposite side, which then turns the steering wheel slightly. It’s why we crash our cars when reaching for something we drop. Source: I’m an occupational therapist.
1. Because the controls are reversed and 2. Because the seat has you facing the wrong direction
Two reasons:
Rear wheel steering actually turns your vehicle by wider angles. That’s why it’s easier to parallel park in reverse. Never forward. If you’ve ridden a bicycle, you know how easy it is to turn it by moving it backwards.
When we drive, we don’t hold the steering wheel 100% still. It doesn’t really have an impact when the vehicle moves forward because it is “forgiving”. But when you drive in reverse, every little steer of the wheel gets amplified by the process described above. You try to correct it by steering in the opposite direction, which makes it even worse.
[MinutePhysics](https://www.youtube.com/watch?v=iFwfexZstO4) has a good explainer.
TL;DR is what everyone else is saying: because you steer with the front wheels, driving in reverse is complicated because you have to steer the front wheels to get the back wheels pointed in the direction you need to go.
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