Brake question on trek 820 w exage mountain
 

I am trying to do a budget rebuild and I am enjoying working on it. I have replaced the front cantilever with a v brake and lever. Also the shifter cable covers were rotting so I have new 7 speed to go with the new 7 sp freewheel.

The rear brake is a huge center pull thats located under the frame behind the bottom bracket. It looks like a v brake down there will extend into the crankset / chain so if I keep the center pull there can I use a v brake lever? thanks

U brakes used shorter cantilever pull levers, V type are long pull , so your potential setup
will use a lot more pad clearance to the rim., and that will absorb some of that longer cable pull .

Bear in mind as the brake pads wear on U brakes , the pad moves off the rim
towards the pivot... the pivot being above the rim that is into the tire sidewall ..

people ignore that, and the tire blows out .

because the brake pad wore out the tire sidewall, at the bead.

Thank you. I will rehab the brake and give it a try with the v brake lever. will definitely double check the pad alignment.

An Avid Speed Dial lever will allow you to adjust the lever pull to suit most types of brakes, and your preferences. http://www.sram.com/avid/products/speed-dial-7-lever

Do that Monthly , flip the bike over and look ,
then move the pads in the mounting slot, as appropriate.