Where we
A) Discuss the theory of gears and climbing
B) Explain how to improve your particular configuration
C) Propose a slightly radical solution to the problem of bike type and gearing.
Below you will find the sections I just listed. I invite you to read or skip the theory as suits you. You will find a set of headings describing the most common road bike gearing configurations. Go to the one that matches your bike to see what you could do to possibly improve your bike’s climbing capabilities. And last, I invite all of you to read and consider the “Radical Proposal.”
Theory of Climbing Gears:
Nomenclature:
Crankset: The assembly including the crank arms, pedals, and the big gears at the front of the bike.
Chainring: one of the big gears on the crankset.
Cassette: The cluster of gears at the back of the bike.
Cog: One individual gear in the cassette.
Tooth: On of the pointy spikey things on a bike gear.
Tooth Count: How many teeth a gear has.
Gear Ratio: Divide the tooth count of the cog into the tooth count of the crank. The number that you get is the Ratio. It tells you how many times you will turn the rear wheel for one turn of the crank. The smaller this number is, the lower your gear is.
This is fairly simple. A lower gear is an easier gear. It’s slower, but it takes a lot less power to turn it. We’ve discussed the idea that you will be carrying more “stuff” on the Cheaha Two Day Tour. That means you will be lifting that stuff, along with your bike, and yourself, up every climb on the ride. Turning a higher rpm (cadence) into an easier gear, will make your day a lot more pleasant.
When you are climbing, you are lifting you and your bicycle (and anything that the bike is carrying) up as well as moving it all forward. The faster you are going forward, the faster you are going up. It’s the lifting that is the difficult part. Lifting mass higher and faster requires more aerobic capacity. That’s the heart and lungs part. If you had perfect legs, you could use just about any gear, and simply slow down until your rate of climb matched your aerobic capacity. The thing is, you don’t. No one does. Being able to turn a lower gear, at a higher cadence keeps you from fatiguing your leg muscles. Slowing your rate of ascent keeps you from going anaerobic. Lower gears let you slow your rate of ascent, while keeping leg effort down, and cadence up. This is a good thing.
Example: Let’s suppose that you have a bike with a lowest gear combination of a 39T chainring and a 25T low cog on your cassette. Further, let’s assume you are riding a bike with 700c wheels.
Your gear ratio is 1.56 to 1. That means you turn the rear wheel 1.56 times for each complete turn of the cranks. At a cadence of 90 rpm you will be doing 11.0 mph.
But suppose that on a particular long climb you find that you are starting to go anaerobic at any speed above 10 mph. Well, to slow to 10 mph, you have to decrease your cadence to 82 rpm. (You can’t downshift, as you are already in your lowest gear.) And the problem is, you must go slower, because you are already anaerobic at this speed.
So you slow down further, and find that at 8.0 mph, your heart rate and breathing rate are high, but comfortable. But now your cadence is down to 65 rpm, and the strain on your legs is getting pretty high.
If you had a 27T on your cassette, you would be doing 10.2 mph at 90 rpm, and 8.0 mph at 72 rpm. Better, but still not great. That’s a lot of legwork, and this is a long climb.
So what if you had a 30T chainring to go with that 27T low cog. Now your gear ratio is down to 1.11. You find that at 90 rpm you are going 7.8 mph. Your heart is not racing, breathing is easy, and your legs aren’t working nearly so hard.
That’s why you want lower gears!
Just incidentally, I’ve found from experience that a low gear ratio of 1 to 1, or less is nearly ideal for this type of riding.
Bike Improvements by gearing types:
“Standard Road Double”
2 chainrings by 9 speed rear.
Chainrings = 53T – 39T
Cassette = 12 – 25
Lowest Ratio = 1.56 to 1
This bike could benefit from a switch of the cassette to a 12.27 for a low ratio of 1.44 to 1. Or, change the crankset to a compact double 50T – 34T. This configuration can yeild the following results.
12-25 cassette ~~ lowest gear ration is a decent 1.36 to 1.
12-27 cassette ~~ lowest gear ration is better, at 1.26 to 1
But there’s an old trick that’s possible with this driveline. Replace the cassette with a mountain bike 11-32. This will require replacing the derailler with a long cage model, and replacing the chain with a longer one. Now let’s see what that does for us.
With the 53T – 39T and a 32T low gear ~~ lowest ratio is 1.19 to 1. Note that this is even lower (at less expense) than using compact double and a 12-27. Cool.
“Standard Road Triple”
3 chainrings by 8 or 9 speed rear.
Chainrings = 52T – 42T – 30T
Cassette = 12 – 25 or 13 – 27
With the 13 – 27 cassette, this bike would have a low gear ratio of 1.11 to 1. Getting there, but it’s possible to improve. If a mountain bike cassette of 11 – 32 where installed (along with the necessary chain and derailler changes) the low gear would be 0.94 to 1. Now that’s getting there!
Compact Double:
2 chainrings by 9 speed rear.
Chainrings = 50T – 34T
Cassette = 12 – 25 or 12 – 27
This isn’t too bad. The lowest ratio, with the 12 – 27 cassette would be 1.26 to 1. Just a bit high for the kind of riding we are planning. But that 9 speed rear lends itself nicely to the replacement with a mountain bike 11 – 32 cassette. The new lowest ratio is 1.06 to 1.
Compact Double:
2 chainrings by 10 speed rear.
Chainrings = 50T – 34T
Cassette = 12 – 25 or 12 – 27
For our purposes, this is a “problem bike.” That crank, along with a 12 – 27 cassette, would yeild a low ratio of 1.26 to 1. This is “doable,” but still a bit high. The problem is, at the time of this writing, there is no lower 10 speed cassette. Mounting a 9 speed cassette creates huge shifting problems. Replacing the shifters, as well as the derailler and chain, would do it, but that becomes prohibitively expensive. The thing is, attempting to do a make over on this kind of bike really doesn’t make sense. You mess up a perfectly good bike, at great expense.
For that matter, some of the possible mods I’ve discussed above, just might not appeal to you. You have a bike. If you like the bike, there are reasons for that. Why risk messing it up? That leads us to…
A Radical Proposal:
Why not get another bike? I often make the case for owning two (or more) bikes. The increased reliability and utility of a two (or more) bike stable are strong arguments. But, if you are considering touring, commuting, or other utility cycling, and you don’t want to mess with your (or mess up) your current ride, this is a good time to consider.
Further, some of the modifications I’ve listed above actually come close to the price of a new bike. Interested? Read on.
Giant makes a line of bikes they call the Defy and Avail. The Defy is the men’s version, the Avail is the women’s version. These are a bit more relaxed geometry than their more racing oriented bikes. In effect the Defy/Avail are already “light tourists”! They come with a road triple and an eight speed 12T – 26T cassette. They have the eyelets and brazeons to mount racks and fenders. The entry level bikes (Defy 3 and Avail 3) in this series are priced at about $800. The next better bikes (Defy 2 and Avail 2) are priced at about $1000.
If I were considering this, I’d plan to get the Defy 3, replace the cassette with an 11t – 32T mountain bike part, and replace the chain and derailler at the same time. (I’d keep the original chain and cassette for later use. But sell the derailler.) The addition of a rack (possibly fenders), a few tweaks, and presto! For a price of about $1000 to $1200, my new light tourist is ready to go tackle Cheaha! It’s an idea worth considering.
Next week we'll get into more on test riding and training, along with some more organizational details.
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