How to Install Top Mount Brake Levers
- 1). Pull the hand-grip off the handlebars. If it is old, cut it off with a utility knife and replace it, too. Using a 4mm hex wrench, loosen the setscrew on the old brake lever clamp. It is located just underneath the handlebars on the brake lever clamp. The brake lever clamp is a flat steel band that holds the lever to the handlebars. Slide the old brake lever off the end of the handlebars.
- 2). Slide the new brake lever on the handlebars. Position it where you like it and tighten the 4mm hex screw with the hex wrench.
- 3). Pull the brake lever shut as if you were braking hard. When the end of the handle opens up you will see a hole that goes through the brake handle housing. Insert a cable into this hole until it comes out the other end of the handle. Pull it all the way into the handle until the little ball on the end disappears into the handle. Release the brake handle.
- 4). Insert the other end of the cable into the brake cable housing. The brake cable housing is a hollow black wire. It has a hole in one end and will be pointing straight up from the bike frame. Push the cable into the housing until it comes out through the brake calipers.
- 5). Loosen 4mm hex nut with the hex wrench, on the opposite brake caliper from where the cable has emerged. Insert the cable between the nut and a bushing and pull it tight with your fingers. When it is as tight as you can get it, tighten the nut as hard as possible. Cut excess cable off with diagonal pliers.
Source...