I agree with the others - knee problems are all about bike fit. Visit your local LBS and ask for help with that. Do not buy any power assisted bike. That is the classic "slippery slope". From there it will graduate to a moped. Then you will need one of those powered wheel chairs in Wal-Mart because your feet get too tired. Then you'll get one for your house because the man on TV tells you he can get Medicare to pay for it and it's FREE! Next thing you know, you are 80 years old and you only stand up to get out of the wheelchair and sit on the toilet or lay down in bed. From there your body rots itself to death. I watched it happen to my step-father. At 82 he got the powered wheel chair for the house and over the next 3 years he just slowly rotted until he died. I would rather have died at 83 trying to go for a bike ride.

In this morning's paper, there was a story about an 87 year old man who rode his riding mower from his trailer down to his mailbox to check the mail, because his knees hurt too much to walk. As he was parking it next to his trailer the mower caught fire and burned down his house. All because his knees hurt too much to walk to the mailbox.

I commute to work 18.6 miles one way. I bought a "touring bike", which is designed for fenders (critical for the rain) and a rack with panniers. Today these are sold as "cyclo-cross" but you can special order them in their proper touring bike configuration, which is what I did. Here is a good link to see what is out there. I found an LBS which carried one of these brands and ordered it.

http://bicycletouringpro.com/blog/to...tance-touring/