Answers

Knees are kind of important when riding a bike. I understand knee pain may be keeping a couple geriatrics off the trails so I thought I would provide some free advice (that, and $7 will get you a cup of coffee at Starbucks):

• Bag the road biking and focus on mountain instead. Road is more repetitive, same body position for long periods. Mountain involves more shifting of weight, different positions which is easier on joints. Also roadies are kinda limp wristed, chicks dig mountain bikers more.
• Stretch. I know your issue is bone on bone, but I found that stretching resulted in better joint alignment and a lot less joint pain. Might make a difference for you.
• Use the easy gears. Spinning fast puts lots less strain on the joints. Big gears are for dopes.
• Jump on the weekday rides - shorter duration - to build up. We like to crush roadies which results on lots of wear and tear on man and machine.
• A couple Advil, an aspirin, and 3 glucosomines washed down with a shot and a beer will take the edge off. Works for me, and I'm not even Irish.

That's all the free advice I can spare right now. Hope that helps.

Chris