I started on a 24" with 150 cranks and then I broke it. I got a 26" Muni with 3" tire and 165 cranks. The Muni didn’t seem like that much of a difference over the 24. Then I got a Nigtrider Pro… Wow! I got dual 125/150 cranks on that and on the flats use the 125’s a lot, but down town and on rough ground, the 150mm cranks are sweeter. I had to learn to do a rolling mount after clinging to things getting onto it and it’s much higher up… but you need to really torque the wheel to get going, but once you are, it’s awesome! get used to speed and getting better response times or UPD’s! I then got a 29" Which had a sleeker and faster tire than the 26er, and was only slightly taller than the muni, but with the 150 cranks was so much faster than the muni and more nimble than the 36er. I just put the 150/125 on the Muni and I’m pretty happy roll back mounting and idling the muni like never before.
Everyone says start on a 20 or 24. I did. I got the Muni so it wouldn’t brake, but all of the quality uni’s I got since the cheap one will prove to last not because they are overbuilt, but just built right.
The 29er is a great all around rig because it’s great at rippin singletrack xc riding, and you can still get speed on the street, but get around people and beat sidewalks better than the 36er. it’s just good all around.
My Muni has a huge tire on it, but since it’s a 26" I can use all my choices of mountain bike tires, Studded, slick snakeskin, mud, hardpack XC, and ride it as a cruiser or offroad and winter steed. It’s burly enough for the roughest terrain in my area, though I am novice.
The 36er is what I use for flying somewhere or longer rides I like to ride bike paths with them or riding along seashores and lakes. I have been commuting with it and people respond to its hugeness. It gets the respect that the smaller wheels don’t get. (no circus music so far…)
If you’ve mastered a 20, the 24 or 26 shouldn’t be very much of a leap. the 29er would be a slight learning curve over the 20, whereas the 36er would be harder, and harder to fit wherever you go.
high speed and dirt but compact 29.
Speed and distance 36
speed and dirt 24, 26
urban tricks and speed 24
urban tricks 20
you said you were on an “urban” campus… that’s a 24" trials or Muni. If you wanted just trials and not commuting you would get a 20" trials rig.