Cycling Cadence and Bicycle Gearing | Hacker News Reader

Cycling Cadence and Bicycle Gearing

kenkifer.com

72 pointsvoberoi21 comments

Interesting article, if a bit involved. Sheldon Brown (of course) has a calculator for gearing: http://www.sheldonbrown.com/gears/.

Due to the terrain here, I have a 50/34 front (compact cranks) and 11-25 cassette., and a preferred cadence between 90-100 depending on the grade or lack thereof.

Sheldon Brown anything gets upvoted by me :) The amount of information and detail of it that man put together about bikes on the internet always amazes me.

It's nice to see people are still finding Ken's pages on the internet useful. He was tragically killed by a drunk driver back in 2003:

http://www.bikeforums.net/archive/index.php/t-37758.html

I'm not sure if it's the book to which the author was referring (he doesn't give any references), but I've found Bicycling Science by David Gordon Wilson [MIT Press] to have a very informative treatment of human power generation. It also includes an entertaining introduction concerning the evolution of the modern bicycle.

http://www.amazon.com/Bicycling-Science-David-Gordon-Wilson/...

I recently bought a single speed, and I think I enjoy it a bit more than my stolen 24-speed. I've done hills several miles long and standing up while pedalling slowly works great. It's like walking up steps two at a time, very slowly. I'd like to get a child trailer though, and I suspect that will push the limits of this experiment.

I also have to accept another problem -- chain slap. With some of my lowest gears, the chain runs loose because the derailleur does not have the ability to wrap that many teeth.

I'm sorry, but that's just a recipe for unreliability. Surely mountain bike dérailleur can take up that much slack? (I only ride road bikes, so I don't know)

If not, I believe the new SRAM Apex groupset will be able to support it - it has an 11-32 cassette (http://www.sram.com/node/2121/brand/sram-road/src/cat)

Yeah, modern derailleurs have fixed that problem - it's a fairly old article. A couple of our bikes have gearing that low, and no issues with chain slap. They use MTB derailleurs.

For instance, in one book (which was much better than most), the author said that a 27-inch gear was the equivalent of walking.

I'm not sure what 27-inches means. I have a 28 tooth back/42 front as my minimum. One day climbing Centiniel drive - to the Lawrence Hall of Science, I noticed an old guy walking was quite able to keep up with me.

It's the gear ratio times the nominal diameter of the wheel. Your gear ratio is 1.5:1. Assuming it's a road bike, the nominal diameter is 27 inches. You would have a 40.5 inch bottom gear. This is a rough, easy-to-calculate way of comparing gearing on different bikes, ones that don't necessarily have the same diameter wheels.

There are better methods around, but this is probably the most popular. I imagine it's because the better methods involve harder calculations.

edit: grammar, punctuation.

I'm not sure what 27-inches means

It's the distance the bike moves in one revolution of the crankset

Nope, that would be "27 inches development". "Gear inches" refers to the nominal wheel diameter multiplied by the gear ratio. Approximately, development == gear inches * pi.

I prefer to use development as my unit, taking into account the actual circumference of the wheel and tire. Only at that point can you compare apples-to-apples among a broad range of bicycles.

I calculated the gear inches for all my combinations and it's printed on a tiny chart taped on my handlebar stem. It's too small to be useful in the middle of a ride though. I do have a larger-print version just showing the gear combinations in order of size, which is more useful mid-ride.

Cycling computers could probably do this for you. They have your speed & your cadence, and if you entered in your cassette & chainrings they could show you your current gear & the next gear up & down (and how to get to it).

I'm not sure how useful it is though. It's not often I'm prepared to do a back & front gearchange at once - I just loose too much speed when I have to easy off the gears.

I suspect that as electronic gear shifting (Dura Ace DI etc) becomes more prevalent the gear system will take care of this for us, though. One click = next gear, no matter how many physical shifts it needs to do.

I would classify this as a "great to know but not in any way essential" for someone, so I am curious why you actually take a chart with you? How do you use it?

I can understand using a chart to plan things out ahead of time, though to me it seems that it is easy to figure out workable gears when starting out just by riding and eventually you know how to shift in a given situation. The more serious riders will refine that by trying out different combinations in more controlled experiments (power meters when you get to Serious Training). The best gearing always depends on the rider.

I tried touring a few times, and didn't really care for it. Instead of my 'Ferrari', it feels like pushing a garbage truck around, both up the hills and down.

If you're riding through Williamsburg in Brooklyn, you won't really fit in if you have more than one gear on your bike... ;)

What if you prefer internal hub shifters?

Then you just skip the math and get a Rohloff Speedhub.

When I have more income, I'll see about comparing that to my Sturmey Archer.

EDIT: Looked at the Wikipedia article. Wow, there's no comparison!

In addition, Shimano has an 11-speed alfine hub coming that's getting close to Rohloff's versatility at a fraction of the price.

Thanks, hadn't seen the announcement. Looks like a nice deal for the price, 400% hits the sweet spot for range and the jumps aren't too bad.

It's good to hear that there's finally going to be some competition in the high end hub gear space. Even if I don't expect to on the market until my Rohloff breaks down, which might take a while... :-)

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