I built one of those same bikes with a shift kit. It's a pretty challenging build, and it requires some customization - one item you'll need is a longer 5/8" keyed shaft because everything is so wide. The stock tire would rub on the left hand sprocket of the jackshaft so you'll need to get a tire that's not so tall and also set back the rear wheel about 1/4" for total clearance. And the rear sprockets & chain on the bike are junk so throw them away & buy a good 7 speed cassette & a heavy-duty chain for the 7 speed cassette. Everything else is pretty OK quality (new seat for comfort is a must however) and as things break just replace them with upgraded items.