Hand brakes are loose and need to be tightened so they will stop the bike. How do I tighten the hand brakes?

SOURCE: Bicycles Brakes Tightening

Are the brakes center pull or side pull?
Center pull would have a nut directly in the center of the brake. Now go to the brake lever on your handle bars and tighten the turn screw where the cable handle is. Keep turning the nut till your brakes grip.
If you have side pull brakes. Then where the cable meets the breaks. Their is a nut that the cable slides through. Loosen the nut and firmly pull the cable till its tight and retighten the nut.

SOURCE: loose handlebars on a Mongoose XR-75 mountain bike

Check the splines on the handle bar. Just loosen the "clamp" and slide the bar over to one side enough so you can tell if the are stripped or not. If they are then replace the bar, if not then reassemble and try to put a littlle extra torque on the bolt.

I have noticed with the 2 of these bikes that I have that the bars do not like to stay tight for long, they tend to work thier way loose about every other time we use them. I just keep tightening them untill the splines strip, then pick up a new bar.

Contact Mongoose for parts info at: www.Mongoose.com under "about" click ask mongoose.

Good luck.