Hey everyone. I am here cause I have recently decided to convert my Marin Larkspur in to a single-speed . I have a friend who sold me some new rims that are ready to go all I have to do is get the crank set and maybe some new forks then get to working on it. The problem is I don't know what size cranks to order for my bike. I guess that is the first question I would start with. Though i would like to look into brands and just generally help on making a good decision on what is a good crank to get. here is a link to the specs of the bike I have
http://www.marin.co.uk/2010/bikepage.php?ModNo=10LA
(mine is an older version). right now I am in a drug study so I don't have access to my bike for a while but would like to possibly order the parts now.

thanks