Good on ya Sam!
Cycling is a great activity. When I started I was 96.9kg (I'm 5'7") and found that it was really hard to ride 5km at first, but within no time was riding 20km no dramas and now 30km is just a normal ride.
Easily dropped 27kg with no change to diet.
It can be great fun cos you get to be out and about exploring, plus you get a sense of speed.
Enjoy mate
