I;ve got a rule that says they charge like infantry. Have you got a rule that says they don't?
Yeah. p. 34 where it says:
Originally Posted by Da Rulz
All of the models in an assaulting unit make their assault move following the same rules as in the Movement phase...
And bikes move 12" according to their entry on p. 53. The confusing thing about the rule on page 51 does say that each unit follows the rules for infantry unless otherwise specified, but then it goes on to specify for jump infantry, the other 12" mover, but not for bikes. Pretty easy to chalk that up to typical GW writing though. The rule on page 51 does supersede the general rule on assaults though, being more specific in scope, and so we have our answer.
It's nice to have a valid answer to a valid question, though it could have done without the attitude. "But that's bollocks (because I say so with nothing to support my claim)", sarcasm, and threats of physical violence are not really helpful when looking for something solid in the rulebook for clarification.