You have to do some short rides 1st to get a sense of what your average speed will be. That's based on how long you go between stops, how long you stop for etc. My personal recommendation is that you limit your day to no more than 12hrs. That means you need to hit the road by 0700. One thing I do is to not eat when I get up. I have coffee, pack it up and go. Have breakfast at your 1st stop. Also, keep your meals light or you'll be falling asleep in the saddle. I've found that on a coast to coast ride, (5 days continuous) I can average about 63miles/hr riding by myself. In a group, that drops to 56 miles an hour. That's for the whole day, so a 12hr day would be either 750 miles alone or 675 in a group. Either way, that's enough saddle time for anyone if you're going to be riding for 5 or 6 days. On a one or two day ride it's what your body will stand. 1,000 mile day is a hard one unless you're a perfect physical specimen. If you're a COBB like a lot of us, I wouldn't even consider riding that far unless you feel you need to prove something.
What it comes down to is are your riding to get somewhere or riding to see the country ? You can combine both on a motorcycle because of the nature of riding, but there's a point at which it becomes more chore than fun. You need to find that point as well as define your personal limits.
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