brakes
You can use V brakes! They manufacture a device that goes at the end of one arm that enables the use of canti levers with V brakes. If the bike has a front suspesion fork you will definately need this. Most of the time for cantis to fail they either bend or the springs are shot. Take the brakes off clean the studs that they bolt to and grease them. Bolt the brakes back on and grease the bolt. Replace the pads, and clean the rims where the brake pads contact. You can clean them with rubbing alchohol, or hot soapy water. Another little trick is to take the pads and push in as much post in the brake as you can they should have lines on the posts. Put the posts on the last line so that you have alot more post going toward the wheel. You should have a minimal amount left on the other side of the brake. Then adjust the straddle hanger to fit. This will make the canti's more sensitive to react.