It has been a long time since I was 12. I'm 57 now. Time has stolen an inch of height. I'm 5' 11" and 176 lbs. I've been as low as 162 lb at age 40, but that was a consequence of inline speed skating 60 miles a week and taking my sons to an indoor rink 6 hours a week. Now, I just tap away at the keyboard...and push my 720 lb Harley up the driveway to stay in shape.
I'm looking at a used Gas Gas Pro 270 -- 146 lbs dry. Even that's too much if you have to drag it up a steep sidehill. Hoping I never have to do that but common off singletrack trails in the mountains.