Thanks for the tip about low step through height. With my current limited mobility in the right hip I already find that the step through height is a little awkward on some exercise bikes that I have tried - and this is pre-surgery. So I will factor this in in my choice.

Yesterday I went to an exercise bike store and asked for a recommendation. I learned what you guys probably already know but I will point it out here in case someone doing a search engine search about this topic of hip arthritis surgery is looking some day:

- recumbent exercise bikes are useful for people that get numb from upright bikes when seated for long work outs. I know that when I go out for an hour ride on my regular upright bike I get some numbness in my butt and groin. This quickly goes away when I stop to take a break so it is no big deal for the type of casual riding that I do. So if I needed to sit on an exercise bike for an hour at a time I might want to choose the recumbent style. But I don't see myself doing that. Twenty minutes sessions on an upright would more likely be my pattern.

- recumbent exercise bikes are easier for people with bad backs. Fortunately my back is fine, so I don't need a recumbent.

- The bigger seat on a recumbent and the position slightly restrict the bend of the hip and leg more than upright exercise bike and I probably don't want to do that.

I am tending toward an upright.