Watching this thread carefully and thanks to all for the advice. I had a similar question early last year before training and prep for 100 mile gravel events. A few things I picked up:
Training:
From this guy who has cycled around the world - rest is vital, don't ride everyday. As many above have noted, put in a long ride on the weekend to harden up your contact points, but do two intense 45-90 min sessions on your bike or wattbike during the week. My old man ran 12 Comrades Marathons and advises that if one can't fit in a 5-6 hour ride on some weekend due to commitments, 2 X 2 or3 hours on a weekend is fine. Importantly, you need 2-3 days off the bike a week to recover.
https://www.youtube.com/watch?v=daLIJZkTvcM&t=59s
Off-bike training;
I personally always battled with ITB and other knee niggles. I found this set of exercises twice a week with some kettle bells mixed in helped me tremendously. After 100 miles of gravel, 3000m of climbing, I still feel strong. Over all it helps with posture and power on the bike. This is the basic set of exercise and build on it with kettle bells / weights. The first week was a joke, I could do a side plank for under 3 seconds, but after 2 months, one is mustard.
https://www.youtube.com/watch?v=HqmwjwTcOY8
Nutrition:
This Aussie lady provides solid, no bulls..t advice. I would watch most of her clips. She covers a lot. What to eat and when to eat, both daily and on the bike. Aside from the usual non-processed foods, good range of meat, dairy, veggies and grains, is the timing, eat a lot early and just after your ride. It helps one stop binging late afternoon.
https://www.youtube.com/watch?v=M_7Ld8pVmMA&t=128s
https://www.youtube.com/watch?v=OZPcWX2EOEE
On race / long ride days, one needs to train oneself to get used to eating a hellava lot the night before and first thing in the morning before the ride starts. In my whole prep process, this was perhaps the biggest revelation. I used to do the Argus after a cup of coffee and take a banana in case. This past year I downed pasta the night before, woke up early and had 2 eggs, and a bowl of oats with yogurt, dates and honey for breakfast, and then downed a date square every hour. The difference is incredible. You not even tired at the finish. Ride home, mow the lawn...
As mentioned above, look at alternatives to commercial energy bars. I researched optimum energy foods per unit mass and dates and peanuts and raisons are pretty close on a fancy energy bar. However, one can make date balls / squares at a really low price. There are lots of recipes on the web.
I did though buy commercial cramp blockers and some gels just for the last 50km. Especially this https://32gi.co.za/ cramp blocker saved me when others were taking immense strain after 5-6 hours in 30 degree heat and loosing salts everywhere. The brand does not cost a fortune.
Spares:
I did the Swartberg Fondo and helped so many people that set off with no tools, no chain breakers, no spare tubes, no tire patches, no pumps (only one bomb), not even ducktape or cable ties. Perhaps I ride alone in Karoo too often, but one really does need to be able to rescue yourself.
Lastly, practice everything. I can't find the clip, but I saw an interview with a guy who has won several transcontinental races and he practices everything so one is always calm and confident. Not only long rides, but diet before and on long rides, fixing punctures, replacing your chain and derailleur, replacing or fixing broken spokes, riding in the dark, replacing batteries and fixing bikes at night, sleeping in a ditch next to the road (serious checking if that little space blanket works), etc etc.
Hope you have a jol.
