Hi kfergos,

In terms of easing into longer daily rides maybe try keeping your commute as-is and adding on a couple of miles of errand running or recreational riding a day. I have a bad knee too and the biggest thing I'd recommend is to make sure that your bike fit is correct. If my seat is even a little too low I'll get knee pain, worse the longer I ride. Also, if my knee is bothering me when I get home I ice and elevate it for a while and take some ibuprofen to reduce the inflammation. It works pretty well to get me back on track for the next day as long as I don't totally overdo it.

Good luck!

Anne