So I was riding my bike on the highway for the 1st time and noticed that when I reach 75+ M/H the front tire starts shaking and also when I push the front brakes the handle bars shake like if the forks are loose...I recently replaced the wheel bearings and brake pads..I know I screw everything tight and back where its supposed to be...any Ideas about whats causing this problem?

 

Check out the steering head bearings. Securely brace the front end off the ground.
Then, grab the forks and pull straight forward and back. Look at the tripple-tree,
you shouldn't see ANY movement, where it mounts through the frame. If so, the bearings are bad. Another sign, while at about 30-40 mph, grab the front brakes
pretty hard. Listen for a "Klunk"-ing sound.

The other thing comes to mind, although not as likely, imo. Wheel out of balance
and/or not true.

That's where I would look first.

Hope this helps, Ern