i have a 99 honda cbr600 f4 and it has a 23000 miles on it... when im driving and hit the front breaks the stearing wheel starts to shake any idea on what the cold be and is it safe to drive

 

deffinetly sounds like a warped rotor to me. i had the same problem and i almost dumped my bike at a stop light because the front tire locked up on sand. i would take them off and check them with a dial indicator to confirm that it is the problem.

 

Sounds like its time for new rotors. Given the mileage, they have probably never been replaced. I would say this is your culprit.

 

put the front wheel up on a stand. slowly spin the wheel and look at the space that exists between the brake pad and the rotor. I will be that it will increase and decrease greatly in some areas.

 

If your rotor has wear grooves in it it could also cause the shaking, even if it is not bent.

 

had the same problem with mine and had to buy new ones.