Calf muscles are fine. Stiffness is on upper portion of lower leg bones on front/sides up at the knee. I contacted my bike dealer for possible bike fit problem and he said he had seen this before. Several were related to type of saddle used and pressure on certain nerves. He stated he had personally experienced a similar issue, but his was his feet going numb. Also stated it could be medically related. Suggested coming in for a bike refit due to my older age and extra weight. Personally know a sports medicine doctor so may give him a buzz and see if we can have a chat about it. Thanks everyone again, great advise.