To start with im not the fittest person on the planet. I got back into cycling as a means to get healthier and potentially make the next 10 years of my life more liveable. so I read all about people hitting average speed of 18-20mph over 50 miles. this is my target and would like to be at this stage for an audax next year. At present i am managing 15 miles with an average of 11mph. so i felt a good milestone would be a 26 mile charity ride, this is in a couple of months. I want to complete this in 2.5 hours max. so any advice appreciated.