JoeBiker wrote:
Jerry, you need to check the frame size, not the tire size.
For road bikes, that is usually specified as the center tube height in cm. For mountain bikes, it is more general S thru XXL (or greater). Both my wife and I both ride 26" bikes, but she at 5'7", she rided a M (I think), and at 6'6", I ride an XXL (which is a little small for me, but that is the story of my life).
Of course, the possibility exist that a cheap bike doesn't specify at all.
Jerry,
I don't mean to rain on JoeBikers parade, but there is no such thing as a "centre tube".
Just for the record; when I wore a younger mans clothes, I was a
competitive cyclist; predominately mountain bike cross country...
I know my $hit.
As far as fit (ergonomics not aerobic) goes Jerry, on a mountain bike, the most important dimension
is the length of the top tube... (the distance from the head tube to the top of the seat tube).
That dimension can be fine tuned by sliding the seat back or forward then tightening
the seat fasteners at the top of the seat post. The reach can be further refined
by different "stems"* (the bit that clamps around the handle bar).
*Around the 90s the design of the Stem fastening (to the forks) on quality bikes
changed radically (for the far better) so you could be in for "culture shock" on
that detail.
It was invented by a kid in Colorado and is now
adopted on good bikes world wide... The "Aheadset"... its patent
ran out in 2010 so there are other makes now.
I could write a book on the ergonomics of the push bike Jerry, but about
that subject I will just say; at least 90% of amateur/recreational riders
have the seat too low, by a very very very very large amount.
Do yourself a favour, and get that seat up. It equals, faster, further, easier.
Typically a good mountain bike has a short seat tube compared to a road
bike, which means the (good) mountain bike needs a long seat post.
See bike frame nomenclature below (sorry it's just a road bike frame):