a passanger in real life affects bikes a ton, Having 4 ppl in a car is not a big difference.
Granted, but there are plenty of things in this game that aren't realistic. I don't think the right place to start focusing on realism was "make all motorcycles turn into a complete pile of sh*t whenever there's a passenger".
There's basically no reason to ever have a passenger, since it drops all the vehicle stats significantly, everything from speed to handling. I'd go as far as to suggest that a passenger probably affects motorcycles more in this game than it does in real life.
It seems weird to go from driving the best vehicle in the game to the worst vehicle in the game just because someone hopped on the back.
Ya, I think it does effect the speed.. the handling for sure. First time I went around a corner at full speed with a passenger freaked me out, "WoAH! That's not supposed to happen!"
Yep, makes everything worse. I don't bother taking my motorcycle out if I'm going to need a passenger at any point, which is really a shame. It'd be cool to ride around with someone and show them how good you are on it, maybe take some sick jumps. As it is, you can barely show them you're able to control the steering, never mind do anything productive with it.
Look at the bright side, at least. You found out how severely it affects the bike's performance through its bad handling rather than its bad speed/acceleration. Try crashing into a fence at "top speed" in mid-air, now that's a pretty crappy way to find out lol.