A:Answer Stability’s: So I’m 6 foot 1, probably 210 pounds and haven’t noticed any stability issues. Feel very safe even at a brisk peddle.
Accessories: I think you can get a cup holder accessory that also makes the desk wider. That’s all they mentioned in the manual at least.
Computer: The included cycling computer measures time, distance, calories burned and speed. It doesn’t have a heart rate monitor so I think it’s just guessing on the calories based on how fast you’re peddling. For what it’s worth my Apple Watch says I burn more calories during a workout than the cycling computer.