So, I'm 33, a father of 2, and my oldest just got his first kickass Mongoose 12"-er...complete with front pegs and training wheels. Since I didn't really want to be 'that Dad' riding my unobtanium roadbike around the neighborhood with him, clad in spandex and my pointy helmet, I went to CL and got a Haro Backtrail X3 for about $50.

After cleaning it up, and making it not so much a deathtrap, I go to ride the thing. Standing and pedaling is fine. But sitting is just awful.

With the 175mm cranks and seattube that is about 8" from BB to toptube, and trying not to be stupid by having 16" of seatpost showing, I'm curious:

Do any of you sit down and just pedal? I'm hitting my chin with my fricken knees here.

I'm 5'-9". I'm pretty sure the TT on the Haro is 20.5.

Is it a frame sizing trend, flexibility thing, or I'm just a dumbass? I can take it...

Durr...just read the 'Does anybody just cruise' thread...looks like I'm out of luck for just doing circles with my kid in the street at 2 mph.

Glad you found the answer. Coincidentally, I bought a Backtrail recently to flip on CL, but not before using it for a few grocery runs and a ~10 mile ride. It's pretty hard on the knees for an old man like me, but I'd probably get used to it after a while.

I'm sticking with my 24"s and looking into a 26" for the longer rides.

Get a big seat like a Sofa -> https://www.danscomp.com/470099.php?cat=PARTS
Im 35 years old,6ft and ride a 21" and I can pedal to the park. Its not slammed but its down low enough to seem slammed. Practice sitting way off the back end of the seat.

This is fairly long, but is a much better article about setting up/fitting a BMX than I could ever write. It's primarily oriented towards BMX racing, but it's also exactly the sort of no-bull**** article you need to read for setting up a bike for just cruising around on.

https://www.bmxbasics.org/new/bmx0695.html
https://www.bmxbasics.org/new/bmx0895.html