how come motorcyclists don't ride in the middle of the...
 

...road? they always ride close to the medium or the shoulder. and how come when they ride in groups, the first one rides close to the medium, the next guy rides close to the shoulder and everyone behind them alternates like that?

The center of the road collects leaking car oil. It also attracts the nut and bolts that fall off vehicles.

It's all about visibility, to see the most of the road, and to ensure other road users see us

pretty simple actually...the middle is where all the oil leaks from cars, and where all the other sediments end up since car tires cut a path, so therefore it's slicker when both dry and wet due to the remaining debris.alternating pattern allows for in case the biker needs to dodge something, they don't push the guy in front or behind off the road or into the next lane... the one in front should ride to the right, or otherwise if they dodged from oncoming traffic, it could cause the 2nd guy to have to avoid by diving the ditch...

Usually, the center of any lane is slightly crowned and makes it more difficult to hold a track. Also debris and oil tend to collect there more than they do down in the grooves.The alternating of bikes is the safest way for a group to ride together.

For the lone biker, I can say through personal experience that I don't ride right up the middle because that's where the grease and slipperiness lie. Cars and trucks passing over the road will coax the coating on the road towards the middle.As for the group, they ride like that in case of an emergency stop. This way they will not be lined up to collide with one another should one not be paying strict attention.As for the first rider being close to the medium, I think that is more a matter of preference.

yeah what they said!