new to lowrider bikes need help ..confused

hi ive recently got into lowriders after buying a chrome lowrider/cruiser last year ,it has 26" wheels and frame .fits me fine being nearly 6ft ..

then i brought another recently name on it says vertical ,it has a slightly different shape ,it has 26" wheels but a sticker on frame says 13 ..this also fits me fine and looks as big as chrome bike

im a little confused   frame 13 & 26 look the same size ..so how do you no what size is suitable for adults ?
and where do you measure from ?

thanks  

The "13" may refer to the vertical, the part of the frame that accepts the seat post, and is measured from the crank bracket up to the where the rear arms connect to the forward top support. Wow, that was a long, run on sentence.  

16, 20, 24, 26 usually refer to the wheel diameter. The bicycle that you are looking at may be a 13" and/or a 26"

I hope that made sense.  

If you still need an answer or have any other questions try contact http://www.streetlowrider.com or http://www.toplowrider.com