I have done a ton more running than cycling in my life (I was a 2500 miles/year guy when running seriously). But there have been extensive periods where I did nothing. And at age 65 my knees and ankles simply are not up to running any longer.

Cycling is a great alternative for guys like us. And I will admit that it is somehow 'more fun' than running. With your running background you will do really well. But you can spend a ton of money here if you choose. But you don't have to make that choice (said the guy who not long ago put a $1300 groupset on a 20 year old EL-OS steel frame).

dave

ps. I also supplement my road bike with a spinner bike as a trainer.