For a 70+Yr old, clients with back pain or knee pain, we would recommend the recumbent bike.

This allows a sitting position without sacrificing the exercise health benefit. It's ergonomic design protects the back and the sitting position protects the knees. The seat is adjustable which gives you the comfort so you focus on the exercise.

We have three main types. Here's a link to our website: https://jumbosportsng.com/search?q=recumbent.

We also recommend you discuss this with your physician.