Risk-Reward and Bike Training
I received an email from an over-50 rider in Australia who is doing l'Etape de Tour in France in July. l'Etape is a cycling event for amateur riders that is done on one of the Tour de France stage routes every year. Some race it. Others just try to finish. This year it will be 198km with five mountain passes to climb. He believes it will take him nine hours to complete and asked if that should be his longest ride in training. Here's my reply...
I've trained a couple of riders in the past for l'Etape. No one this year though. Quite an event.
How long should one's longest ride be when the event will take nine hours? To answer this, the primary consideration is the risk-reward ratio. Every workout, including long rides, has a reward in the form of increased fitness associated with it. And every workout also has a risk associated with it. This means that there is the possibility of an overuse injury, burnout and overtraining.
Viewed as a graph, at least for most well-conditioned riders I've coached, the reward line would rise little in the first few minutes and then become gradually steeper for perhaps two to three hours before it would begin to rise at a decreasing rate some where around four hours. Eventually it would plateau, meaning even though the athlete is riding longer, fitness is no longer benefiting from the increased time. The risk line on the graph would remain rather flat for a couple of hours and then begin to gradually rise, perhaps around three hours. Starting at around four hours the risk line would get steeper. By about six hours, I believe, it would be quite steep and would intersect the reward line. This is the point that I believe the ride should be stopped. Risk now exceeds reward.
This is not to say there isn't a psychological benefit associated with going the entire goal/projected time in one ride. If you feel really intimidated by the prospect of riding for nine hours then there may be some mental relief from having ridden that long once in training. But having done so in your own back yard doesn't mean you'll be able to do it in the mountains of France. If I was coaching you we wouldn't ride that long until the day of the event. We would, instead, do rides of up to six hours and would gradually add in more climbing so that eventually your long ride is made up mostly of hills (which, by the way, also increases the slope of the risk line). It's more important to get the intensity right than the duration. I would also have you do a ride of this duration and intensity no closer to the event than three weeks. Six hours is a long time in the saddle, especially if you are climbing a lot. It will take several days to fully recover from this. Perhaps a week. That would leave two weeks until the event to taper and peak. You can read about peaking on my website.
Of course, there is a lot more that goes into preparing for such an event than just building fitness. One other major issue is on-bike nutrition--fuel, fluids, sodium. Be sure to address this as it has as much to do with your success in such an event as does fitness.
Good luck! I hope to hear that you did well.