From personal experience, a lighter bike, more senior friendly gearing, race-fit clothing, better sports and general nutrition, learning the importance of rest, using the gym and I’m sure something I have forgotten, has allowed me to ride about 1 MPH slower now than I did as a 40 year old. Speed is not always the thing, but being able to go farther and climb with less effort has its benefits. All of this I have learned thanks to many forum members and the University of YouTube. AND I really don’t care if a company is selling me a product that allows me to go farther or faster or both as long as it works or has a good placebo effect. Double AND, I still stop and take plenty of pictures along the way because I just enjoy nature and being outdoors.