Hi Doo, I would look at measuring the length of the wheelbase on your current bike & not to go any shorter, wheelbase is important for comfort & handling if you're a taller guy. Smaller frames have shorter top tubes & less wheelbase, OK you can use a longer stem/seat post & even shove the seat back but the bike will feel more lively & less comfortable plus you'll look too big for your bike, Kinesis frames have fairly long chainstays & decent a fork rake, most manufacturers have their geometry available.