I have pretty much given up on racing. I got bored riding round in small circles. I just ride round bigger circles now and rarely pay for the privilege. As for getting slower when you hit 40….well I didn’t really notice it though in reality, once I passed 38 my sub hour days for a 25 were fading fast.
I am not going to see 50 again sadly but my XC speed is still pretty reasonable and I have a respectable sprint too. The way I ride has changed though. Decades on and off road have taught me when to push hard and when to ease back with the result that my riding has become more efficient.
thomthumb has hit the nail on the head though, you have to put the work in and three rides a week, as you get older, is pretty much a minimum – well for me anyway. I find that I take longer to recover (fully) nowadays and it is getting later and later in the year before I can really feel the fitness kicking in. It arrived about 2 weeks ago! I have been averaging about 120 to 150 miles a week – two or three XC rides and a long road session (about 70 to 80 miles) a week.
I seem to have allowed myself to enter a race – for the first time in ages, so we’ll see how I get on. I think it will be less of a problem being fit, than being motivated!