nun

Chill Dude

njkayaker

Okaay.

MassiveD

Hard to say what you should run though I would probably be on the middle front chainring around 36x23 depending on the details, straighter chain line.

Stuff to look at is position, and how your knee is over the pedal; cadence; shoes; spinning ish, hard to really do this but not doing the opposite; aero position, nothing crazy here either, but an awareness of aero is about all that works if the wind picks up badly enough; efficient use of the gears, your effort should be even, your speed should vary, if possible... Bike handling, efficient brake use, etc... are also important to safety.

MassiveD

I have no opinion on the 10% training thing in athletics, but often the reason that people do not perform in touring are totally different. Presumably a performance athlete is nearer the wall of what can be achieved, you can't keep improving by 10% for ever. The reason I can improve by 250% over a few days, after a 20 year layoff, and with serious injuries, is because even though I am a bad athlete, the base was in there somewhere. It took me a long time to become a good climber, but up until the implosion really took hold, I could go back to the rock, and repeat routes I had done for decades afterwards. A lot of it is just knowing you did it once.

If you take someone who is reasonably (I don't mean as an athlete, just an every day way) fit, and give them good gear, and the basics of proper technique, they should be able to go a lot further on a bike than they can on foot, and people can hike 25 miles a day over rough terrain with the same weight our bikes carry, if they are just in decentish shape. Give them a chair, and gears, and let them roll on smooth roads, you think they should be able to knock out a century... Nah...

njkayaker

A 40 inch gear at a cadence of 80 RPM gives a speed of around 9.6 mph.

Assuming your pedaling technique is reasonable, the gear inches is not important. It's your speed that matters. A 10 mph moving average for a flat century (without a headwind) is on the low side.

Some things to keep in mind (some of which people mentioned earlier).

* For most people, their average speed drops as the ride gets longer. That is, the average MPH they do for a 100 mile ride is going to be less than what they do for a 20 mile ride.

* Many people do centuries that are organized. These rides have a limited time the course is "open". That ends-up meaning the 100 miles has to be done within 9-10 hours including stops. This ends-up being a 10 MPH total average (100 miles divided by the time between when you start and when you end). If you use this as a rough target (it's a reasonable target because it's common), that means your moving average has to be higher than 10 mph. (Note: Given that you are doing your own ride, it's OK to take longer but the organized century numbers indicates what many other people do normally.)

* Long/frequent stops have a large impact on your overall average. Riding at a slower pace might be better than moving at a faster pace and taking lots of stops (that are long).

* A common problem that people have on long rides is pacing. That is, they often start out too fast and poop-out at the end of the ride. One reason do do 50-60 mile rides is to work-out your pacing.

* Long rides reveal issues that just don't show up on short rides. Working your distance up lets your body adjust to being on the bike for long periods of time and allows you to discover and fix issues instead of being surprise deal breakers on a century.

* People's average speed tends to drop as it gets dark. If your ride is going to include riding in the dark, expect that you are going to be slower. You should try to minimize the time you need to ride in the dark.

(There doesn't seem much reason you won't be able to do the ride even with a 10 mph pace. It might take you a while, and you might need to ride some in the dark, and you may hurt a bit afterwards. The idea is to make your ride better and reduce the problems you could have.)