SCHWINN SIDEWINDER 7 speeds or 21?

Hello!

You can see by now that I'm a newbie, a 79 year old 'little boy', and
I want to be able to bike at many different speeds..zipping down bike
lanes or across the Arizona desert before the band of angels start
comin' after me.

You all must be tired of me by now because I keep changing my mind. I
can only pay up to $160 for a halfway decent (I'm partial to Schwinn),
Schwinn 26" MB,

Walmart only had the Sidewinder for $139, but it doesn't say how many
speeds it has.... 21? Maybe another Walmart or Amazon?

Thanks so much for your patience with me.

Mike