Why do 10-sp cassettes have the smallest cog as 11 or 12?

[slidey]

I'm sure the more bike-technically inclined of you here will be able to give me an answer to this question, but I can't quite figure out why cassettes don't have 10t cogs? That way, someone riding a compact 50/34 could benefit greatly by just opting for such a cassette.

Related: A couple of years back in the MTB world there was some research into a 10 speed cassette with a 9t cog (Link here (http://www.pinkbike.com/news/Ten-Speed-and-the-Nine-Tooth-Cassette-Cog.html))

[rice rocket]

Did you read the article?

Requires a custom freehub.

[bart998]

Gee, I don't use my 11t. I would like to start at 13t and add some at the other end or in between... guess I'm just getting old. :eek:

[Anarchist]

You really think people want a 135 inch gear??

Really?

[slidey]

I did read that in a cursory manner so my understanding might be half-baked, but wasn't that necessary as they went into 9t whose diameter is the same as the diameter of the freehub? This shouldn't be the case with a 10t cog...or is the difference in diameters close enough to still warrant this overhead?

Did you read the article?

Requires a custom freehub.

[bluesea]

I could use an 11x50 and want to avoid wider gear spread, but also want to keep my 27t climbing gear. :rolleyes:

[slidey]

You're looking at 53-39 + 10-??. I'm looking at 50-34 + 10-??, in which case it is a cheaper option to try out the 53-39 with just one easy swap.

You really think people want a 135 inch gear??

Really?

[Chance]

Why do 10-sp cassettes have the smallest cog as 11 or 12?

Shimano offered the Capreo 9-speed group mainly marketed at small-wheel bikes with a 9-26 cassette. Technically the hub and cassette could have been used with smaller rings to accomplish the same you are describing (except for the 10-speed part).

My opinion is that once you are in the 11T range using 700C tires, it becomes easier to install extra large rings if you need added top end for whatever reason. If a 50/10 is what you'd like, the same for the most part can be accomplished with a 55/11.

Where you would have to compromise is that overall gearing range becomes tougher to accomplish with bigger rings and cassettes. In that light it's hard to follow why some insist on using cassettes with 13t small cogs instead of going to smaller rings. Overall a rider "normally" gets more flexibility with smaller cogs because they offer greater gearing range given typical derailleur limitations. Manufacturers know this and offer more 11t and 12t cassettes than any other size.

So the short answer to your question is that there are probably too few riders that would use anything greater than 50/11. And for those few they can buy larger rings.

[cp43]

The difference between 50x11 and 53x11 isn't very big, 119.5" vs 126.6". If you're looking for lower climbing gears, that small difference in top end is a great trade to make for easier climbing, IMHO.

Also, adding a 10 tooth cog to a bike running 50-34 cranks may give you a similar gear spread to running a 53-39 crankset. But, it won't really feel the same as riding a 53-39. The big difference, other than gear ratios, between the two is the size of the gap between the big and small rings. You'll still have a bigger gap with the 50-34, 10 tooth small cog or not.

Hope this helps,

Chris

[Anarchist]

You're looking at 53-39 + 10-??. I'm looking at 50-34 + 10-??, in which case it is a cheaper option to try out the 53-39 with just one easy swap.

(50/10)*27 = 135

If you can push that, other than straight downhill, you should be riding in Italy right now.

[palincss]

You really think people want a 135 inch gear??

Really?

The only way 9 or 10 tooth sprockets make sense is for bicycles with 17-20" wheels. The only 10T sprocket I know about was designed for Moulton bicycles which use wheels in those two sizes; and the only cassette that has a 9 tooth sprocket is the Capreo, which was made specifically for small wheelers.

I can't imagine what use people with 26 or 27 inch wheels would make of high gears that high.

[christian]

In that light it's hard to follow why some insist on using cassettes with 13t small cogs instead of going to smaller rings. This to me, is obvious.

Have you compared the gear charts on a 50-34 with a 12-25 and a 53-39 with a 13-26? The 12-25 lacks an 18t cog, so the big ring steps are 62 inches, 68 inches, 76 inches. The corresponding ratios on a 13-26 (53/39) are: 59, 65, 72, 77.

I, for one, don't like a 12% gap in my (admittedly lower end of) cruising range.

[GRAVELBIKE]

My name is Mark, and I use a 13t small cog with a 48t big ring.
Hi, Mark!

[slidey]

Well, this isn't a Q motivated by personal experience just one that got me thinking when a teammate told me a few days back he was planning on changing his setup to a standard because of spinning out on his compact with a 11t cog.

Moreover, I do resort to my 11t cog on my 55 chainring very frequently during descending, so I don't think pushing such a gear is as big a deal as you are making it out to be. On the other hand, 50/11*27 = 123, and it is clearly conceivable how some people might be spinning out on that ratio going downhill.

EDIT: This is now a trade-off between flat cadence, and downhill cadence. 135 gear inches would be very hard to keep consistently hammering on flats, but 131 ain't all that bad and hence mfr's have opted to go for the sweeter spot by opting to changing chainrings. I think this was what Chance was hinting at...the compromise.

(50/10)*27 = 135

If you can push that, other than straight downhill, you should be riding in Italy right now.

[jimmythefly]

http://www.excelsports.com/image/Shimano%20Cassette%20Cog%2010sp%2011T.jpg

This is an 11T cog. If you were to make a cog with 10T, it would be a smaller circle. So small that it would no longer fit over the freehub body.

That's it. The reason most cassettes don't have 10t cogs is that it is physically impossible to make them that will also fit on a normal Shimano or Campy freehub body.

[Mark McM]

Other issues with small sprockets:

The reduced chainwrap (i.e. number of teeth engaged with the sprockets) increases the probability of a skipping chain. The reduced chainwrap also increases tooth wear.

Gear size is inversely proportional to rear sprocket size, so as the sprocket size is reduced, the relative jump in gear size to the next smaller or large sprocket increases. For example, the gear size with a 16 tooth sprocket is only 6 percent larger than a 17 tooth sprocket, but the gear size with a 10 tooth sprocket is 9% larger than with an 11 tooth sprocket (50% bigger gear jump).

At a certain point, making sprockets smaller becomes impractical, and you have to make the chainrings larger instead.

[palincss]

At a certain point, making sprockets smaller becomes impractical, and you have to make the chainrings larger instead.

And right now, as it has been since the early 1980s, when the Moulton AM-series was introduced, the smallest practical sprocket is 9T (currently available in the Capreo group). Campagnolo fans willing to purchase special hubs and cassettes from Moulton (assuming they'll sell to non-Moulton owners -- not a given: they used to have a special 10T Shimano sprocket that they sold only to Moulton owners) can get their special 10-28 11speed cassette.

These make perfect sense for 17" and 20" wheeled bicycles.

[Ahneida Ride]

My name is Mark, and I use a 13t small cog with a 48t big ring.
Hi, Mark!

Same here !

[palincss]

Me too. And one of my bikes uses a 13T small sprocket with a 46T chain ring. 97-100 inches is plenty high enough high gear for me (except on a tandem, of course).

[Chance]

This to me, is obvious.

Have you compared the gear charts on a 50-34 with a 12-25 and a 53-39 with a 13-26? The 12-25 lacks an 18t cog, so the big ring steps are 62 inches, 68 inches, 76 inches. The corresponding ratios on a 13-26 (53/39) are: 59, 65, 72, 77.

I, for one, don't like a 12% gap in my (admittedly lower end of) cruising range.

Can't follow the logic of comparing two completely different gearing setups. These two are so different as to be apples and oranges.:confused:


P.S. -- And yes, I've looked at every combination under the sun at one time or another. Still think that if the total gearing range being compared is not approximately equal then one is wasting time for the most part.

[palincss]

Still think that if the total gearing range being compared is not approximately equal then one is wasting time for the most part.

If the point of the exercise is to shift the gear range downward to eliminate useless high gears in favor of additional low gears, knowing how the change affects gears in the mid-range can be very valuable.

[christian]

The compact arrangement referred to has a 34 inch low and the standard a 39 inch low. Tops are within an inch of one another (from memory). I'd argue they're close to identical - the standard trades the lowest gear for together steps where they're more useful.

But yeah, that's why I use a 13-26 - small steps in the cruising range, don't need lower gears than a 39-26 in Westchester, and can't spin out a 53/13 for longer than 30s on the flat anyway...

[palincss]

The compact arrangement referred to has a 34 inch low and the standard a 39 inch low. Tops are within an inch of one another (from memory). I'd argue they're close to identical - the standard trades the lowest gear for together steps where they're more useful.


There's a lot of difference between a 34" low and a 39" low.


But yeah, that's why I use a 13-26 - small steps in the cruising range, don't need lower gears than a 39-26 in Westchester, and can't spin out a 53/13 for longer than 30s on the flat anyway...

And that's exactly why we study gear charts and pore over this stuff so carefully!

[cfox]

My smallest cog is a 12. I use it all the time when I clean my chain.

[DerekG]

If you can spin out a 53/11 you are getting paid to ride your bike for a living and it should be no problem for you to come up with a solution for the race(s) where this is happening.

For most mortals, this is why spinning out your current set-up is very unlikely.

http://cyclingskills.blogspot.com/2009/05/speed-leg-speed-and-spinning-out.html

[shovelhd]

If you can spin out a 53/11 you are getting paid to ride your bike for a living and it should be no problem for you to come up with a solution for the race(s) where this is happening.

I must be doing it wrong. :help:

[Chance]

The compact arrangement referred to has a 34 inch low and the standard a 39 inch low. Tops are within an inch of one another (from memory). I'd argue they're close to identical - the standard trades the lowest gear for together steps where they're more useful.

But yeah, that's why I use a 13-26 - small steps in the cruising range, don't need lower gears than a 39-26 in Westchester, and can't spin out a 53/13 for longer than 30s on the flat anyway...

My reply should have been more comprehensive at the expense of being too wordy. In your example (even if the gears were close to the same range) gearing is quite different because you picked up the 18T sprocket in the cassette (making it a closer ratio cassette) at the expense of using wider chainring spacing (wider 50/34 versus tighter 53/39 ring spacing). This gets into the compact versus standard discussions which aren’t necessarily part of this thread. Could be but don’t have to be.

In my opinion similar gearing with exception of small cog size (in order to isolate advantages to one variable at a time) would be 52/39 with 13T small cog, versus 48/36 with 12T small cog, versus 44/33 with 11T small cog, and so on. These numbers were picked strictly to make numbers come out the same. Big ring gives a 4:1 ratio and small ring a 3:1 ratio. From there we could compare near equals.

Extrapolating this comparison, a 10T small cog would use an equivalent 40/30 ring setup, and a 9T small cog a 36/27 ring setup. Cassettes would then be chosen to have near-equal overall ranges. This is just one set of examples with near-equal values. Others could work just as easily.


By the way, my personal preference is to have both tight gearing and wide range. The best way to get there is to use as many gears as you can practically buy. For me that involves a triple.

[christian]

My reply should have been more comprehensive at the expense of being too wordy. In your example (even if the gears were close to the same range) gearing is quite different because you picked up the 18T sprocket in the cassette (making it a closer ratio cassette) at the expense of using wider chainring spacing (wider 50/34 versus tighter 53/39 ring spacing). This gets into the compact versus standard discussions which aren’t necessarily part of this thread. Could be but don’t have to be.
No. While I agree with your follow-on thoughts, if you re-read my post, you'll see I'm comparing: 53/39 with 13-26 and 50/34 with 12-25. So in that scenario, you get BOTH narrower chainring spacing (14t vs 16t) AND an 18t, using the standard crank.

A comparison of 53/39&13-26 to 50/36&12-25 eliminates the chainring delta and actually further makes my case for me:

53/39 - 13/26:
106.00 78.00
98.43 72.43
91.87 67.60
86.13 63.38
81.06 59.65
76.56 56.33
72.53 53.37
65.62 48.29
59.91 44.09
53.00 39.00

50/36 - 12/25
108.33 78.00
100.00 72.00
92.86 66.86
86.67 62.40
81.25 58.50
76.47 55.06
68.42 49.26
61.90 44.57
56.52 40.70
52.00 37.44

But you bring up an excellent point about ratios. It's very important to keep chainring spacing in mind relative to specific cog sets. (Boy I love gearing threads.)

[christian]

Extrapolating this comparison, a 10T small cog would use an equivalent 40/30 ring setup, and a 9T small cog a 36/27 ring setup. Cassettes would then be chosen to have near-equal overall ranges. This is just one set of examples with near-equal values. Others could work just as easily.You can't extrapolate that way, though. Tooth counts on cassettes are (obviously) integral, and the percentage difference between a 9 and a 10 are different than the percentage between a 13 and a 14 (comparing top gear and second highest gear).

If you want closer spacing, relatively bigger chainwheels and cogs will always provide that, provided the 2-teeth gaps in the cassette are at the same spot, the chainring difference is held constant, and the gearing range is the same.

[christian]

Again to be plain, if you look at the ratios of cogs with a 39t small chainring and a 13-26, the ratios of chainring to cog are:
3.00
2.79
2.60
2.44
2.29
2.17
2.05
1.86
1.70
1.50

To get equivalent ratios on a 30t chainring, you'd need cog sizes of:
10.00
10.77
11.54
12.31
13.08
13.85
14.62
16.15
17.69
20.00

Obviously, even a corncob 10-20 10sp doesn't get you the same spacing (because the deltas at the lower-tooth count cogs are bigger as a percentage).

[Chance]

No. While I agree with your follow-on thoughts, if you re-read my post, you'll see I'm comparing: 53/39 with 13-26 and 50/34 with 12-25. So in that scenario, you get BOTH narrower chainring spacing (14t vs 16t) AND an 18t, using the standard crank.

A comparison of 53/39&13-26 to 50/36&12-25 eliminates the chainring delta and actually further makes my case for me:


In gearing, "delta" number of teeth is not the correct way to calculate effective gearing. We need to look at ratios. Delta is only important in regard to derailleur capacity and such.

53/39 = 1.359

50/34 = 1.471

There is quite a bit of difference in chainrings. We can't go by number of teeth alone because the effect on gearing is greater as the sprocket sizes get smaller. To make the overall gearing similar in the examples one would have to then use a cassette with tighter range. To me that's comparing apples and oranges, but if it works for you that's great.

Also please note that as mentioned by others you are comparing two examples with significantly different low gearing. That in itself makes the comparison difficult to follow (at least for me).

[ergott]

I could have used an 11 today.

http://app.strava.com/activities/54580617#993060459

[christian]

In gearing, "delta" number of teeth is not the correct way to calculate effective gearing. We need to look at ratios. Delta is only important in regard to derailleur capacity and such.

53/39 = 1.359

50/34 = 1.471

There is quite a bit of difference in chainrings.That's why I made the point that 50/36 is a better comparison, even though it's a somewhat more rare combo:
53/39 = 1.359
50/36 = 1.388, substantially equivalent.

You said: it's hard to follow why some insist on using cassettes with 13t small cogs instead of going to smaller rings.

I'll simply point out that a 53/39 13-26 gives you a 106 high, 39 low, and four ratios between 70 and 90 gear inches in the 53 (common riding speeds).

A 50/36 12-25 gives you a 108 high, 37.4 low, and three ratios between 70 and 90 gear inches in the 50 (common riding speeds).

Ergo, I'd say they're functionally equivalent, except for gear spacing between70 and 90 gear inches. Given the amount of time spent riding in the 70-90 range, where I live, it's pretty clear that 53/39 13-26 is better for me. Hopefully, that helps you understand why some riders would choose a 53/39 with a 13-26 rather than smaller chainrings. It results in more pleasant gearing.

[Ralph]

http://www.excelsports.com/image/Shimano%20Cassette%20Cog%2010sp%2011T.jpg

This is an 11T cog. If you were to make a cog with 10T, it would be a smaller circle. So small that it would no longer fit over the freehub body.

That's it. The reason most cassettes don't have 10t cogs is that it is physically impossible to make them that will also fit on a normal Shimano or Campy freehub body.

That.....and a lot of us ride where we don't do much down hill pedaling, and I would rather have no gaps at all from 13-19 and then 21-23-26 for most of my riding. If you spread the cogs out too much, like starting with 10, you get gaps. And even when I ride where it is hilly, I don't ever pedal past 28-30 MPH anyway...and a 13 will do that. I got no reason to pedal past 28-30, even when riding in steep hills....not racing. So don't get the problem. For what you want..11 speed seems better to me. With 11, you can have that tall gear, plus good coverage thruout the whole cog set. So much depends on where you ride, and how you ride. Some of the strongest riders I know....guys who ride those brevets....(or whatever you call them), do not run tall gears. They coast down hills mostly. I do too.