So, I turned out to be much stronger than I thought on the bike ride. Not so say I finished first. Just in the top half, but I really don’t have any hills to climb in training, or rollers, or really anything except wind. In particular, I can’t climb very well. Not awful, just not fast. I would get passed or hold position. What really surprised me was the downhill. I would often rocket by people on the way down. The same kind of thing happened during the Old Tascosa Classic last year. Give me a hill and I can crawl up it then fall down it faster than anybody. This is generally how I passed people. I gained so much distance on the downhill run that by two of these downhills I didn’t see anyone behind me. Too many people were near my weight to attribute it all to heavy bike and heavy rider. I say heavy bike, because I saw a lot of carbon fiber bikes without carrier or bags. I’m probably 15 lbs or more heavier.
My gears are pretty good, but I have begun looking for something to extend my upper range. This really ups your speed on a downhill or tailwind. I hit this limit in training due to wind and on the ride due to hills. This gear would really be too large on a flat to push and even a moderate downhill would be tough. On a good, long downhill I would hope to push from 40 mph to 45 mph. The converse of the granny gear for hill climbing.
I would also like a to find a lighter crank and possibly shorten the crank arm. Big Green has a triple crank, but I saw doubles on the ride and they are significantly lighter. Weight savings in rotating parts is multiplied from your effort instead of subtracted. That means tires, rims, cranks, and cluster. Tires and rims get weaker and less durable when lighter. Cranks and cluster less so.
Sheldon Brown seems to be a good website for gears, especially touring. They even have a cluster he designed. This page has a listing for Shimano gear ranges. That’s when I think I found my answer to my downhill speed.
I purposefully bought a touring bike. One that would have wide gears for the hills I grew up with and a long, comfortable frame to ride on for a long time. The crank is 28/38/48 and the cluster an 11-32. For comparison, the gears on nearly all the clusters for 9 spds in the table top out at 21, 23, 25, or 27 and a common double ring gearing is 39/53. What does this mean?
Gear Inches is not the best metric, but fairly understandable. It comes from the old Penny Farthing days when the only way to gear a bike was to make the wheel bigger. So, a gear inches of 41 would mean you are riding 41″ direct drive wheels. And a gear inches of 110 would mean you are riding on 110″ direct drive wheels. Low numbers are for mountain climbing and high numbers for racing.
According to the calculator on Sheldon Bown’s site a 39/53 crank with 12-21 cluster gives a range of 49-116 gear inches on 25mm wheels. A similar 12-25 cluster is 41-116 gear inches and a similar 11-34 cluster is 30-127 gear inches. My triple crank is 28/38/48 with a 9 speed SRAM cluster of 11-32 for a range of 24-119 gear inches on 35mm wheels.
You can see that the low gear is dramatically lower on my triple than a double and the high gear is slightly higher on my triple. Only the wide 11-34 cluster offers a higher gear. The low gear or granny gear, in my opinion is enough to offset any weight lost by moving to a double crank.
Now, I should say I don’t know the gearing on any other bikes. Besides noting a double or triple crank it’s difficult to see the difference in a 9 and 10 speed or even an 8 and 10 speed. I’m just conjecturing about reasons for why I fall like a greased stone down an icy hillside.
By the way, you might be wondering, “Why not have a triple crank with 10 speed cluster to get a 30 speed bike?” The problem, especially for triples, is overlapping gears. I have several gears that are only 1 or 2 gear inches difference. This isn’t really noticeable. And you’re spinning the extra weight of the sprockets.
I would like to expand the range a little. A 20 gear inch lower and a 130 gear inch upper would be nice. That’s a little lower and a good bit higher.
I’m thinking of maybe replacing my lower and upper crank rings from a 28 to a 26 and a 48 to a 50. That slightly expands the range, but probably not enough to replace the front derailleur.