Come To Florida!!
http://gainesvillecyclingclub.org/gcf/index.html
Leave those hills behind! We have two Centuries here in Gainesville, Florida in October- back to back, but of course you don't have to do both. Or you can do the easier Century Saturday, (no hills) and a small part of the other one Sunday! They have _excellent_ food and SAG support.
The first one, Santa Fe Century was my first Century ever, last October. I trained up to 92 miles, but only because the trail I trained on was 46 miles one way. I think you could get by with training up to 80.
Don't be discouraged about the metric Century wiping you out! That is normal for the first time you do your longest distance ever. You should have seen me when I did 200k. I thought, oh, that's only 24 miles further than a Century- an hour and a half at the most...But it was super windy that day, and the hills were bad, and my legs were like JELLO when I got off my bike. I didn't think I could drive home. I didn't want to even pack up my bike. I felt like asking a kid in the car next to me if he would pack up my stuff for $5! I was so disappointed in my performance. But then- three weeks later, I did a 300k ride, and it was so much easier! I was amazed!! That's how your body builds endurance- you stress it, you rest, and it's ready to go further!
My general training schedule is a long ride Saturday. Increase your distance for your long ride 5-10 miles per week. Sunday ride half the distance of the Saturday ride. Two or three weekdays ride 1-2 hours per evening- even as short as 45 minutes is ok for one ride. The next Saturday, increase 5-10 miles again! I had a _very_ difficult time when I increased my distance in the 50-70 mile range, then it got easy.
Running out of nutritional energy is easy to do if you're not paying strict attention to how many calories you take in per hour. One of the first signs is mental fatigue, and feeling like you just can't go on. A gel or bar can really perk you up, in 10-15 minutes, when you hit this point, as well as just getting off the bike and sitting in the shade for a few minutes. It's better not to let that happen, though, but be aware that even if it does, all hope is not lost- you can recover from it if you recognize it quickly.
My first Century was really a big deal to me. I did another one a month later, and it was 104 miles, and that seemed _so much further_!! But then I did some long training rides, in the 80 mile range, and did that 200k in January, and then a Century and a 115 mile exploration ride the weeks after that, and suddenly that distance of about 100 miles seemed relatively easy- still a _long_ way, but I was not exhausted afterwards like I used to be, and was eager to ride again the next day.
You _are_ right, a lot of it _is_ mental. But I think that if you do everything you can to adequately prepare- have a good training base, have a good bike fit so it isn't hurting you, have your nutritional plan in place, know the route, have the proper clothing for the conditions- then your brain won't be able to find some little thing to use as an excuse for quitting.
Good luck!
Nanci
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"...I'm like the cycling version of the guy in Flowers for Algernon." Mike Magnuson