Larry's point about being able to pick it back up is interesting because that is sort of my situation now. I did a really hilly 300k brevet recently and my longest ride in over a year was 34 miles and overall, almost no volume. But, I had been backpacking some. It is partly that the "legs have memory" but probably also that with experience one learns not to be stupid. You learn how not to push too hard and ride within your limits. This is how I use a power meter on longer events, whether races or brevets. It serves as a governor. On the recent 300K, I just backed off the power for the whole ride. I would normally be one of the first finishers but it took me almost 2 hours longer, because I knew it made more sense to ride at 18-19 mph instead of 22-24 mph on the flats and to really take it easy on the difficult hills. You learn when the legs are just being a little baby and not really hurting and you know when to tell them to shut up.
If you are going to do like a 24 hour RAAM qualifier, they are often on a loop course of maybe 50-60 minutes in length. If you can have support to be ready each lap to hand a bottle of your preferred drink, this will save an enormous amount of time vs going to your cooler, unclipping, getting the bottle, getting back on course, etc.
Hydration and nutrition is something you have to figure out. I need less fluid than other riders. I need less food than other riders. If I am riding at 20 mph on the flats, I burn between 450-500 calories per hour with a body weight of 180-190 lbs but this is only taking me 115-120 watts or say maybe 40-50% of FTP. This is about all I can hold after 12 or hours. At that percentage of FTP, most of the power coming from burning fat. I might only need to replace 200 calories per hour of carbs. This is not too hard to do if you are diligent. Some riders can process up to 350 calories per hour of carbs, whether in drinks or snack type stuff. You want to frequently eat a little bit of what you like or what your body is telling you to eat. Frequently might be every 20-30 minutes bit into something. Or, you may learn that you like energy drinks or homemade brews using maltodextrin or the like. If you are getting sick to the stomach, there are four likely reasons. 1. Too much fluids. 2. Too much food. 3. Overheated. 4. Lack of fitness
I would encourage you to look into randonneuring if not already a member. The standard distances are 200, 300, 400, 600km. Completing all four distances makes you a Super Randonneur. The events are usually in late winter into early summer and are spaced pretty nicely to build long distance endurance. You can pretty much ride them at your own pace and they are non competitive, so, they give you a good chance to work out nutrition, pacing, riding at night, lights, etc. I used to be able to do 200 mile training rides but it takes a lot of motivation and at my age, I don't do it. A brevet on the other hand can get me out there. YMMV.
The biggest bang for your performance buck are wheels and tires. Ride fast tires. Don't be afraid of fixing a flat. If you have to, practice fixing them. GP5000 over Gatorskins can save you something like 20-30 miles on a 24 hour event, please don't make me calculate, plus actual Crr on roads is much higher than those we read about on steel drum. Also, on a fast bent like V20, your speed is sufficient to justify fast wheels in the 50-80 mm depth range....if you can handle them in wind.....most can.
For whatever reason, the first few hours riding (only on a bent), I have to pee like a racehorse. Maybe 6 times per hour. This is a disaster in a race. I use a condom catheter that attaches over the "device" and has a removable connection to a tube. On country roads, I just wait for a 1% downhill and pull the tubing out to water the grass on the side of the road as I glide along. I apologize if this grosses anyone out. Urine is sterile. After some hours, my kidneys behave and I can remove the thing.
