Written by: Greg Kopecky
Added: Thu Feb 06 2014
Before we begin, let’s take a quick look at how we talk about gearing with a few examples.
This refers to a cassette. The smallest cog has 11 teeth, and the biggest cog has 25. The numbers are separated by a dash. This does not tell us anything about the number of cogs in the cassette (it could be a two speed cassette… or a twenty speed). It just tells us what the extreme ends are. To know how many cogs are in that cassette, we simply say, ‘9-speed’, ’10-speed’, and so on.
This refers to a pair of front chainrings. The big ring has 53 teeth, and the small ring has 39. The numbers are separated by a slash. This does tell us how many rings are on the crank. If it was a triple system, there would be a third number (for example, a 52/39/30 triple).
This is referring to a specific gear selection. In this case, the chain is wrapped around the big 53 up front, and the little 11 out back. The numbers are typically separated by an ‘x’.
These are describing drivetrains. A ‘2x10’ system is pronounced ‘two by ten’. It has two front chainrings and ten cogs in the rear. A ‘3x9’ has three front chainrings and nine cogs in the rear.
Start with a niner…
Although bikes used to have all types of drivetrains with 5, 6, 7, or other numbers of rear cogs, we’re going to start our discussion with 9-speed systems. Why nine? For the most part, that’s the smallest number of rear cogs that you’ll find on the majority of modern road and triathlon bikes. I just don’t see that many 7 or 8-speed systems these days.
Chatter on internet forums revealed that many riders wanted wider-range options. Indeed, we saw spy photos of Pro Tour cyclists using custom 11-25 cassettes; sprinters needed the 11 for the finish, and the 25 just to get there in one piece. I was among the home mechanics who put together my own custom cassettes.
As 10-speed systems came out, we unfortunately saw many of the same cassette sizes. A 9-speed 11-23 and 10-speed 11-23 both have the same total range; the 10-speed cassette just has slightly smaller ‘jumps’ between gear sizes. If memory serves, I believe Shimano came out with an 11-25, but only in mid-level 105 components (at least for the first year or two).
Shimano did what they always do, which is make slow but very calculated moves. They finally began offering 10-speed 11-25, 11-27, and 11-28 into their various systems. Ultegra always seemed to get the highest number of options. It is also worth noting that Shimano also retained great gear range by virtue of their triple chainring offerings, which didn’t ‘need’ the larger cassettes. Unfortunately for them, much of the industry had decided that triples weren’t fashionable any longer.
Clearly, cassettes were getting wider ranges at a very rapid rate. The following shows a few different cassette options. We start with a very common 9-speed cassette – the 12-25. As you can see, 10-speed allowed us to conveniently add an 11 to that while retaining otherwise identical ratios. As we add wider range 11-28 and 11-32 options on top of that, it’s clear to see that our gear ‘jumps’ are getting larger and larger:
Now that SRAM and Shimano are both making 11-speed, they’re finally offering some of the options that athletes can really benefit from. I’ll admit, I was initially very disappointed to see 11-speed come out. Do we really need this stuff? Is it worth forcing consumers to upgrade their wheels? In my opinion, the difference between 9 and 10-speed was nothing to write home about. Some of the wide range cassettes were nice, but they didn’t offer closer ratios than 9-speed.
Now that I have been on 11-speed Dura Ace 9000 for a year, I must sheepishly admit that… it is better than 10-speed. Adding that cog seems to make much more of a difference than the switch from 9 to 10 did. To illustrate why, I’m going to show you some more fancy graphs.
If we start from a 10-speed 11-28…
On the smaller end of things, let’s start with a narrow 9-speed 12-23. 10-speed gives us an 11-tooth cog, while 11-speed gives us a full 11-25 range.
What should you ride?
How do you know what to use? Unfortunately, it is impossible to make any sort of a blanket recommendation. Cassette size requirements vary hugely based on a rider’s fitness, local terrain, preferred cadence range, chainring sizes, and other factors. At some point, you just have to try for yourself. When in doubt, ask other local riders what they’re using before plunking down that cash.
Some people insist that, regardless of anything else, they MUST have a 16-tooth cog in their cassette. I thought the song said that three is a magic number, but some say it’s 16. The gear just ‘feels right’. It’s the Chosen Gear. Personally, I don’t get it. I’ve heard this request from people with 700c wheels, 650c wheels, and all different sizes of chainrings (and fitness levels). All of these things affect the gearing of your bike. A 16-tooth cog on two bikes can result in two completely different gear ratios if the wheel size or chainring sizes are different. Try it for yourself; you may love the 16, and you might not care.
Do we need both of those chainrings?
In my mind, this discussion brings up a big question: Do we need two chainrings up front? As we’ve seen in mountain biking, SRAM has been reducing the number of chainrings in their drivetrains at a very rapid rate. Triples died in favor of doubles, and doubles gave way to the single ring setup (called 1x, or ‘one-by’). With eleven gears in the back and a huge 10-42 mountain bike cassette, the rider can select an appropriate front ring to meet the needs of their local terrain. It is also worth noting that the small 10-tooth cassette cog required a new freehub design that is proprietary to this system (e.g. you need a special rear wheel).
What might those cassette options look like? When going from an 11 to a 10-tooth small cog, you gain quite a bit of gear. For example, a high gear of 53x11 is almost exactly the same as a 48x10. That’s right – you could easily run a 48-tooth chainring up front and have plenty of high gear. The question, then, is what type of low gear would you use? Would a 48x28 be enough? If not, would a super-wide spread be acceptable for road riding? Looking at the chart below, even going as wide as 10-28 loses the beloved 16-tooth cog.
We hope this discussion has been ground breaking, fantastic, or at least a little educational. Does your bike have 9-speed, 10-speed, or the new 11-speed? Do manufacturers offer the cassette sizes that you want, or are there others that they’re missing? Do you hate numbers and just want to ride your bike? We’d love to hear your comments.
All charts © Greg Kopecky / slowtwitch.com
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