mountain bike sizing
I have a question about mountain bike sizing. I'm just not sure how to compare them (if you can) to road sizing. I've been riding road bikes since the beginning of the year and have two, one is a 53cm and the other is a 54cm. I guess they are both considered mediums.
I've been looking at treks and they have sizes like 16" and 18", just don't know how to compare to road, where should I start? I'm 5'9" - 30" inseam. Any inputs would be appreciated. I can't believe after getting two bikes this year I'd want another, but I'm getting sortof hooked (lost 25lbs this year). I don't know how riding MTB would fit into my fitness plan (if I really have one), but it sure looks like fun!
Thanks in advance..