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1

I was looking at purchasing some Sram Rival components. Looking at the available cassettes, there is a big variety of sizes available:

  • 11-23: 11-12-13-14-15-16-17-19-21-23
  • 11-25: 11-12-13-14-15-17-19-21-23-25
  • 11-26: 11-12-13-14-15-17-19-21-23-26
  • 11-28: 11-12-13-14-15-17-19-22-25-28
  • 11-32: 11-12-13-15-17-19-22-25-28-32
  • 12-25: 12-13-14-15-16-17-19-21-23-25
  • 12-26: 12-13-14-15-16-17-19-21-23-26
  • 12-27: 12-13-14-15-16-17-19-21-24-27
  • 12-28: 12-13-14-15-16-17-19-22-25-28
  • 12-32: 12-13-14-15-17-19-22-25-28-32

Now I can understand why someone would choose a cassette based off of how many teeth the big gear has. Some people live in hilly or mountainous areas and desire a higher number of teeth. Some people live in flat areas where they simply won't use those cassettes with a lot of teeth on the big gear.

But why would anyone ever choose to buy a cassette with 12 teeth on the small gear instead of 11? 11 teeth = higher maximum speed. I doubt many people buying a nice set of components (Shimano, SRAM etc) would ever say "I don't need to go faster so 12 teeth is fine with me."

What's the point of 12 teeth when you could opt for 11 instead?

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3  
The 12-25 gives you one more cog in the middle of the range, where you'll spend the most time and hence most want to "optimize". – Daniel R Hicks Sep 26 '12 at 23:53
@DanielRHicks - exactly right. I have an 11-25, and I find I very often have a "gap" where a 16 fits perfectly. I can find the number of times I've used the 11 on one hand with a couple fingers and thumb left over. – JohnP Sep 28 '12 at 18:17
With this many cogs in the back, do you still have a front derailleur? – Kaz Oct 9 '12 at 17:33

6 Answers

up vote 14 down vote accepted

If you want to maximize your max. speed, go for an 11 tooth cog. If you want to maximize your average speed, unless you're a pro you probably are better off without it. Even cruising at 40km/h does not require and 11 tooth cog.

For example, take a look at this table, showing cruising speeds for a 11- 21 tooth cassette: cruising speeds for a 11- 21 tooth cassette

And compare to this table for a 12 - 25 tooth cassette:

cruising speeds for a 11- 25 tooth cassette

You can see that the 11 tooth cog is only really useful for cruising speeds that riders at the professional level can maintain, or for short bursts. So, like I said, if you aren't trying to break your own max speed record, you may be better off with a 12 tooth cog.

(Tables screen captured from bikecalc.com. Check it out.)

I remember reading a while back about how most riders can't maintain a high enough wattage output to make an 11 tooth cog worthwhile, but I couldn't turn it up. Maybe another contributor will post it.

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1  
Just to clarify: in the context of these tables, "cruising" means pedaling at 90rpm. – amcnabb Sep 27 '12 at 2:21
1  
"You can see that the 11 tooth cog is only really useful for cruising speeds that riders at the professional level can maintain, or for short bursts." This of course assumes flat terrain. People who live in mildly hilly areas might find themselves frequently cruising at a higher speed. It all depends on where you live and how you ride. – amcnabb Sep 27 '12 at 2:26
Is the row along the top the number of teeth in the front chain ring? – Jakobud Sep 27 '12 at 3:07
Yes, although practically you are very likely to be in a chainring with either 50 (compact crank) or 53 (standard) teeth while using a 12- or 11-tooth cog. – Stephen Touset Sep 27 '12 at 4:10
up vote 8 down vote

For me, and for many riders that come through my shop, the 11-25 is missing the critical 16t cog, which (at least for me) is the sweet spot. That is, the gear which I don't tend to spin out of, and that doesn't turn in to a grind fest.

If I'm doing a Euro trip, then I will run an 11-28, with a compact front. But at home, for daily riding, a standard 53/39 with a 12/25 is perfect.

For what it's worth, the 11t cog was designed to give a compact crank, with its smaller front range, the same or similar top speed as a "standard" setup, which at the time was a 53/12 maximum.

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up vote 4 down vote

Some people will never get the chance to use the 11 teeth setting, whether this is through not being fit enough or another reason.

So they can opt for the slightly longer expected lifespan of the 12 (lower wear per tooth) and the slightly narrower gap between ratios which can make gear changing less of a struggle.

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You can compensate for the lack of the 11 tooth cog with a bigger chainring on the front as well. – Kibbee Sep 27 '12 at 0:14
Your logic is that 12 teeth wears slower than 11 teeth just because there are more teeth to handle the forces from the chain at any given time? – Jakobud Sep 27 '12 at 3:09
up vote 2 down vote

In addition to the other answers, there's also cyclocross. People don't typically ride as fast in cyclocross as they do on the open road, thus lower gears might be better.

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up vote 2 down vote

The simple answer is that people (racers especially) like closely spaced gears so they pedal as closely as possible to their optimum cadence.

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And of course they know their optimum cadence down to three significant figures. – Kaz Oct 9 '12 at 17:05
up vote 1 down vote

Different strokes for different folks is all. Guys with arms like legs and legs like people have no need for a stump puller or even a 25 sometimes and are wishing for a 10 until they discover what a Campy set up costs while in my world of recreation and fitness a 12-28 seems almost perfect most of the time and I've even considered a 13 or even 14-27 from the 6600 junior cassettes. My first road bike was a '73 Fuji S10S 10 speed with a 14-17-20-24-28 and it seemed to be all I really needed (at the time) but now, at almost 70 yrs, bigger gears are my friend.

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