Continuing my return to cycling after an almost two decade hiatus I have stumbled upon a great way to increase ones stamina. Most bicycle training focuses on lighter bikes, better shoes, better clothes, special foods etc. In short anything that can be sold in a bicycle shop.
The secret to increasing your endurance is to work your muscles more. The secret to working your muscles more is more weight. Instead of trying for lighter weight do like I do and strap 18lbs in a pack on your back and head out for your 15 or 20 miler. After you get used to this you could probably take it on your 40 and 50 milers.
I went out for a weekend ride last weekend without my pack and man oh man did I feel like a featherweight with more endurance and less work from my legs than ever.
The reason I started riding with a pack is because I now commute to work on my bicycle, and I must bring my laptop, power supply, change of clothes, enough food to see me thru the day and back home, kindle fire, plastic bags to enclose electronics in case of rain and what not. Right now I’m doing about 60 miles a week with an 14-18 lb bag on my back in 80+ degree temps.
Not to shabby for a 40 year old office worker.