Economy versus Collapsible
I got both bikes--an upstairs Bike 1 Economy and a downstairs Bike 2 Collapsible.  They are both very stable.  The brakes work well for me  when I want to transfer on and off--I haven't tested hills!!  The Collapsible one comes all put together which was  very nice and has a little wire basket I can carry my iphone and reading glasses, etc. in.  They are definitely not off road so if you have a  gravel driveway, you might consider another tire type.  We have a lot of  stickers so I didn't want air tires.  I don't think the collapsible's tires leave marks as easily and I find the knee pad softer but the line down the middle marks my leg so I put a hand towel on it.  It does fold into a little box shape  but my husband just throws them into the back of the car so the time it takes to fold up  doesn't seem worth it.  It might on a plane or with car space considerations.
Rating: 5 stars