Has opinion, will express
The answer comes with experience, not using a calculator or some website. The answer also changes depending on the rider's fitness.
If you can't answer the question now, you haven't done enough riding.
FWIW, the 100 pound load seems like a pretty good place to make changes that would enhance your trip. That is a very heavy load and not necessary unless you have some very special reason to be taking a lot of heavy stuff. Even with inexpensive camping gear and only moderately aggressive trimming of non essentials, 30 pounds of gear is pretty easy to achieve. Assuming a 30 pound bike that puts you at 60 pounds of bike and gear. The difference is like night and day in riding comfort in my experience.
My bottom gear is more like 17 inches. I find myself crawling up hills at 2.2 mph quite regularly! So my cadence down there is probably more like 45! With my mildly corpulent BMI 25 body and my mighty steel 40 pound bike and then the lock etc. I am probably hauling more like 225 pounds up the hill. I imagine I am in that territory at a slightly small grade because 170 watts is too much for me to sustain... if the power meter on my rowing machine is to be believed!
Originally Posted by wphamilton
But anyway that kind of low speed low cadence is pretty much how I get around on my bike! The price I pay for living in the Catskills Mountains!
just another gosling
As I said somewhere above, your calculation might surprise you. So #1 , less weight. #2 , train for it. Take your bike out to a long steady hill, put it in a big gear until even with a strong effort your cadence is around 50. Do 10 minute hill repeats like that. I usually do a set of 3, once or twice a week. You can also do these on a trainer or rollers if you have enough resistance. They really work. Learn to pedal circles at low rpms without moving your upper body. Do it all with your legs. Move your feet 'round and 'round. Never walk. Instead, stop to rest for one minute at a time. That's faster and better for you.
Originally Posted by wphamilton
My low gear is approx 17 gear inches.
Once my cadence falls below 70 rpm, I'm looking to dismount and push.
I've just got back from a months jaunt around the south coast of Western Australia.
Its pretty hilly by Aussie standards so there was lots of portage and thankfully associated weight loss.
My jeans are thanking me for it.
I just wish my Rohloff warranty allowed me an inch lower in gearing but alas I'm at the limit utilising a 34T front ring and 16T sprocket on my Surly Ogres 700c wheels clad in 2 inch Mondials.
I switched out the inner 26T chainring for a 24T. Yesterday I went on the ride to Vogel State Park that I was worried about. I tried to put my bicycle on a diet but still left with the loaded bike right at 100 lbs.
I was was highly pleased! The lower gearing was a definite help. I went to that lowest gear rarely but I was glad it was there when I wanted it. And having a lower gear to go to when my energy is hitting a low in the afternoon is definitely a good thing. Late in the ride some of the "easy" hills were asking for that lowest gear.
Last edited by Walter S; 04-19-14 at 04:33 AM.