Cycling UK Forum

I have been riding all my life (59 years of age) and have been over the Alps, sportives etc. I can never do a ride averaging over 15mph. My running is much better and my upper body strength is pretty good and I can regularly do 40 press ups. My friend who does much less training and has a BMI of at least 5 more than me, beats me up every climb and every flat, comfortably. I have very little in the way of leg muscles but there have been lots of cyclists such as Chris Froome who are similar. I also climb out of the saddle more that anyone else I know. I find it very difficult to push myself cycling except later in the day when my legs feel completely warmed up. I also struggle to get my heart rate very high.

How can I improve this? Is it just squats, lunges etc?