Milkbone, I don't get why you would want to leave your bike computer off the bike if you are recovering from an illness. You need to track your improvement, and your first day back on will show you how much fitness you lost, and then you can watch the improvement over the weeks. It doesn't matter that you lost fitness because it is to be expected.

Last November I was knocked sideways off my bike by a side gust, was unconscious for 90 minutes, and spent the weekend in the trauma center with a fractured rib cage, a punctured deflated lung, and a severe concussion. On January 1 I was back on my bike. Sure the computer numbers were quirky, but then I was laboring with a right lung that wasn't totally healed and hurt with the mending bones. It was pure delight to watch my progress via the bike data and in only two months I was able to go up a 13% grade with my lung inflating and oxygenating my blood normally. It is FUN to regain fitness, not some big nasty chore.

This forum has a lot of negativity regarding bike computers, but it doesn't mean the advice has to make any sense for you. It makes sense for others for whatever reasons, but gosh, if you are recovering from a medical condition, the bike computer is a plus, not a negative. If you want to watch your physical improvement, and to know exactly how bad it is on the first day, then use the bike computer. Using a bike computer doesn't mean you don't ride. It merely provides the data to show how you are doing on any given ride, and you can track the data over time if you desire, or not if you don't desire.