Originally Posted by
zjrog
Which is why I'm looking at a fat bike. Nice and squishy, and easier on my back. .
That is incorrect since tires do not replace suspension. Assuming you are riding hard surfaces...When the tires are aired up to 10 psi or more you will get thrown around a lot due to the rigidity of it all. When the tire pressure is lowered you consistently bounce up and down like a basketball due to the fact there are no rebound or compression dampening adjustments like there are on a shock and fork. It will be worse on your back.
If you want something nice and squishy and easier on your back you are better off getting a full suspension 29er bike.