The Altegra 12-speed sprocket from my previous article was
11–34T, but
↑This is a Dura-Ace 12-speed sprocket 11–30T
that I'd shot separately for an article.
With 12-speed, the low-gear cluster
has 4 cogs at 11–30T, but 5 cogs at 11–34T.
And looking at this, what caught my attention was that
the bottom three cogs below the low gear were
21, 24, and 27T—quite the combination.
I've written out the six gear combinations available
on the 7700-series Dura-Ace 9-speed sprocket.
Of these, the three cross-ratio options have 16T,
and the 12–21T additionally has an 18T.
The reason the 11–23T doesn't have an 18T is
that "when adding one more cog to the 8-speed 12–23T,
they chose 11T instead of 18T."
As you can see, the 9-speed has this construction:
"If you want a 25T or 27T in the low gear,
give up the 11T top." In my usual style, I'd say
27T is a tooth count that's "uncool to use regularly
except during actual hillclimb races like Tsugaike or Yatsugatake
and in the days immediately before them."
Back then, compact front gears weren't widespread yet
(110mm PCD was originally a touring bike crank standard anyway),
and while some makers like Ritchey Logic promoted alternatives,
road racers (not road bikes—actual road racers) would look silly,
so it never caught on widely.
So aside from the triple front option,
the standard was 39×27T, or if you went with
a non-Shimano 38T inner cog, 38×27T,
as the lightest gear ratio available.
By the way, 38×27T is roughly equivalent to 34×24T.
I'll write out the tooth count of the "widest-ratio"
(keep that in mind)
12–27T.
Looking at this 9-speed sprocket,
if you set three wishes:
"I'd like an 11T on top,"
"I'd like a 16T in between,"
"I'd like a 30T in the low,"
then with 10-speed, one of those three wishes is granted,
with 11-speed, two are granted,
and with 12-speed, all three are granted.
And the Shimano 12-speed road sprocket
11–30T has exactly this same tooth configuration.
And in the case of 11–34T,
the only difference is
"removed the 16T from the 11–30T and added 34T."
In other words, with the current Shimano 12-speed sprocket,
even if you choose the more cross-ratio option,
as long as you shift between 17–27T,
it's no different whatsoever from
the "widest-ratio" 9-speed Dura-Ace sprocket.
The Shimano 12-speed 11–30T overlaps with the 9-speed Dura-Ace 12–27T
by 5 sprocket cogs in the 17–27T range,
but with the 11–34T, it overlaps by 9 cogs.
Overlapping by 9 cogs compared to the 9-speed sprocket
means it contains all of them.
So the 12-speed 11–34T is constructed by adding
11T on the top and 30T and 34T on the low
to the 9-speed 12–27T.
Conventionally, people say things like
"more sprocket cogs make it easier,"
but if you ask me, almost nothing has changed.
This phrase "easier" is ambiguous,
and while "easier climbing because there are bigger low gears
(but slower)" isn't wrong,
the kind of "easier" that means "easier because more intermediate tooth counts are filled in"
is barely realized in recent multi-speed developments.
I made a speed table assuming flat riding on the outer gear
at cadences of 90, 95, and 100 rpm.
Assuming a hobby racer,
the front tooth count is 50T.
The tire is calculated at 25C equivalent circumference.
When 15–19T is 15, 17, 19—a 2T gap—
shifting one cog while maintaining the same cadence
changes speed by roughly 4–5 km/h.
This is a huge change; pedaling resistance
either lightens considerably or gets much heavier.
50×15T at 90 rpm and
50×17T at 100 rpm,
and 50×17T at 90 rpm and
50×19T at 100 rpm
are roughly the same speed,
but this means that to maintain the same speed
by shifting one cog within the table range,
you need to change cadence by
about ±10 rpm.
I inserted 16T and 18T in between,
making 15–19T a full ratio.
What changes as a result is:
(within this 15, 16, 17, 18, 19T range)
"to maintain roughly the same speed,
you only need to change cadence
by 5 rpm per gear step."
This reduces leg strain during shifting,
gives you wider options between pushing (low cadence)
or spinning (high cadence) to maintain a given speed—
that's the other kind of "easier."
Here, I'll draw out with arrows
the speed range of 15–17T at 90–100 rpm (red in the figure above)
and the speed range of 17–19T (blue in the figure)
within the cadence range.
With 16T added,
shifting changes from 15→17→15T
to 15→16→17→16→15T,
and with 18T added,
shifting changes from 17→19→17T
to 17→18→19→18→17T.
If you ask which gives bigger benefits,
at hobby racer speeds,
the latter seems more significant.
It's extremely rare for hobby racers to maintain
a solo flat cruising speed of nearly 40 km/h.
And if someone has the legs for that,
they probably wouldn't often choose the 50T outer anyway,
so I've calculated the table speeds for 50T.
Even with 50T, can you maintain
100 rpm on the 15T, say, for 30 minutes?
If not, there's no point making a table
for 52T or 54T speeds!
That's my reasoning.
So if someone said I could add either 16T or 18T
to an 11-speed sprocket with
11, 12, 13, 14, 15, 17, 19, 21, 24, 27, 30T teeth
to make a 12-speed sprocket,
the 18T would probably be more useful
for most people.
But because of the convention
"if you're filling in teeth, start from the top,"
the 18T isn't actually added in this scenario.
It's like in golf, where a 14-club limit forces you to carry
a difficult 3-wood that beginners can't use,
preventing you from including other useful clubs suited to your skill level.
Unlike golf club sets, sprockets don't offer freedom in configuration—
but that's inseparable from excellent shifting performance, so it can't be helped.
As for the doctrine-like devotion to sprockets
with just 5–6 clubs—putter, approach wedge, utility, 7-iron, 9-iron,
plus maybe one wood (→here)—
but there's more to the 18T story . . .
12-speed sprockets simply
don't have 18T!
Of course there may be exceptions, but
Shimano's 11–30T and 11–34T, and the 10-speed 11–36T,
SRAM's 10–28T (incidentally, 16T exists only in this tooth count),
10–30T, 10–33T, 10–36T,
and Campagnolo's micro-compact-ified
Super Record wireless (excluding the traditional 12-speed)
11–29T, 11–32T, and 11–34T—
across all major component makers' 12-speed sprockets,
there's no 18T option in any tooth count.
Campagnolo has three tooth options, and on all of them
the top eight cogs are
11, 12, 13, 14, 15, 16, 17, 19T,
so when pro riders cruise flats,
the feel is identical regardless of tooth count,
and they always have 16T without exception.
For top-tier pros, having a light 16T on the easy end
when cruising flats at 53–54T outer is handy;
12–16T is "easier" than 12–15T. In terms of the table above,
they're running different outer cogs and speed zones outside the table,
so whether 18T is available or not
isn't really a problem.
↑So this is the second use of this image in this article:
15–19T with no 16T or 18T.
15, 17, 19T gaps aren't even new to 9-speed—
even 6-speed sprockets achieved this 2T spacing.
The whole point of my argument is: this 2T spacing
can only be avoided in the current 12-speed lineups
by choosing the most cross-ratio (laugh) 11–30T,
so there's no way gear count increasing made things easier!
The current 12-speed does make climbing easier
with larger low gears,
but it hasn't made flat riding easier
in the 15–19T range on the outer cog,
with that ~40 km/h cruise speed.
By the way, if I change the outer from 50T
to 52T or 54T in the table above, the range becomes
more like ~40 km/h cruising rather than ~40 km/h cruising.
Also, whether 21T and beyond are spaced 2T or 3T apart
makes a huge difference.
The leg strain is completely different between
21–27T shifting as 21, 23, 25, 27T
versus 21, 24, 27T.
If a 28T low gear is enough,
I'd rather see 21T onward as
21, 24, 27, 30T (30T is uselessly light but unavoidable)
rather than
21, 23, 25, 28T (only the last is 3T spacing).
With 12-speed, you could realize
11, 12, 13, 14, 15, 16, 17, 19, 21, 23, 25, 28T,
and it would be hugely useful if they offered
a version with 28T removed and 18T inserted:
11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 23, 25T.
The micro-compact 10T top Super Record wireless
10–25T has this configuration minus 18T, plus 10T.
Hmm, so close.
Campagnolo's Gibli-exclusive 9-speed sprockets
11–19T and 11–21T—the former
is a full cross with consecutive natural numbers,
and Campagnolo's 10-speed junior-spec sprocket
that appeared only in Veloce grade
14–23T also has full-cross teeth.
If you use the 17, 18, 19, 20, 21, 22, 23T run in winter,
when you switch back to a normal sprocket in spring,
you get the feeling of "19, 21, 23, 25T? That's too many gaps!"
We're already in an era where some people
"have only ever owned and ridden disc-brake road bikes,"
and some of those fit that description
and race for a corporate team—
but such people probably don't find it weird
that disc road frames have different stiff points and balance
than rim-brake ones, or that they're harder to throw around.
They probably don't mind that the bar ends are heavy
or that bikes with brake hoses internally routed through bars and stems
have steering weight unique to that design.
So having a few low cogs spaced 3T or 4T at the end
just feels like "that's how it is,"
because they've got no reference point.
I'm not saying that's bad,
but as machinery gets more sophisticated, techniques get lost.
I think many people
"have never owned or ridden a mechanical-shifter road bike,"
and while that's not common, mechanical front derailleurs
are very reluctant to shift from inner to outer on uphill grades.
You have to stop pedaling once,
then stomp down hard all at once.
But electronic front derailleurs just brute-force it with motor power,
so that unweighting pedal technique isn't necessary.
So it's not bias—many people who've started road cycling recently
are actually pretty bad or careless about this point.
Though I haven't had zero chain drops in the last 20 years
(actually zero since entering 2024),
I've had no front-derailleur or front-shifting troubles.
Because I don't have a front derailleur installed.
↑You're probably thinking, "In 20 years,
you've also lost the unweighting front-shift pedal technique,"
which is fair.
But I can probably still do standing-pedal double-lever knee shifts.
↑Piling on another weird flex of having used drop-bar shifters,
which is the audacity.
Besides, knee-shifting is a useless technique that deserves to be forgotten anyway.
11–34T, but
↑This is a Dura-Ace 12-speed sprocket 11–30T
that I'd shot separately for an article.
With 12-speed, the low-gear cluster
has 4 cogs at 11–30T, but 5 cogs at 11–34T.
And looking at this, what caught my attention was that
the bottom three cogs below the low gear were
21, 24, and 27T—quite the combination.
I've written out the six gear combinations available
on the 7700-series Dura-Ace 9-speed sprocket.
Of these, the three cross-ratio options have 16T,
and the 12–21T additionally has an 18T.
The reason the 11–23T doesn't have an 18T is
that "when adding one more cog to the 8-speed 12–23T,
they chose 11T instead of 18T."
As you can see, the 9-speed has this construction:
"If you want a 25T or 27T in the low gear,
give up the 11T top." In my usual style, I'd say
27T is a tooth count that's "uncool to use regularly
except during actual hillclimb races like Tsugaike or Yatsugatake
and in the days immediately before them."
Back then, compact front gears weren't widespread yet
(110mm PCD was originally a touring bike crank standard anyway),
and while some makers like Ritchey Logic promoted alternatives,
road racers (not road bikes—actual road racers) would look silly,
so it never caught on widely.
So aside from the triple front option,
the standard was 39×27T, or if you went with
a non-Shimano 38T inner cog, 38×27T,
as the lightest gear ratio available.
By the way, 38×27T is roughly equivalent to 34×24T.
I'll write out the tooth count of the "widest-ratio"
(keep that in mind)
12–27T.
Looking at this 9-speed sprocket,
if you set three wishes:
"I'd like an 11T on top,"
"I'd like a 16T in between,"
"I'd like a 30T in the low,"
then with 10-speed, one of those three wishes is granted,
with 11-speed, two are granted,
and with 12-speed, all three are granted.
And the Shimano 12-speed road sprocket
11–30T has exactly this same tooth configuration.
And in the case of 11–34T,
the only difference is
"removed the 16T from the 11–30T and added 34T."
In other words, with the current Shimano 12-speed sprocket,
even if you choose the more cross-ratio option,
as long as you shift between 17–27T,
it's no different whatsoever from
the "widest-ratio" 9-speed Dura-Ace sprocket.
The Shimano 12-speed 11–30T overlaps with the 9-speed Dura-Ace 12–27T
by 5 sprocket cogs in the 17–27T range,
but with the 11–34T, it overlaps by 9 cogs.
Overlapping by 9 cogs compared to the 9-speed sprocket
means it contains all of them.
So the 12-speed 11–34T is constructed by adding
11T on the top and 30T and 34T on the low
to the 9-speed 12–27T.
Conventionally, people say things like
"more sprocket cogs make it easier,"
but if you ask me, almost nothing has changed.
This phrase "easier" is ambiguous,
and while "easier climbing because there are bigger low gears
the kind of "easier" that means "easier because more intermediate tooth counts are filled in"
is barely realized in recent multi-speed developments.
I made a speed table assuming flat riding on the outer gear
at cadences of 90, 95, and 100 rpm.
Assuming a hobby racer,
the front tooth count is 50T.
The tire is calculated at 25C equivalent circumference.
When 15–19T is 15, 17, 19—a 2T gap—
shifting one cog while maintaining the same cadence
changes speed by roughly 4–5 km/h.
This is a huge change; pedaling resistance
either lightens considerably or gets much heavier.
50×15T at 90 rpm and
50×17T at 100 rpm,
and 50×17T at 90 rpm and
50×19T at 100 rpm
are roughly the same speed,
but this means that to maintain the same speed
by shifting one cog within the table range,
you need to change cadence by
about ±10 rpm.
I inserted 16T and 18T in between,
making 15–19T a full ratio.
What changes as a result is:
(within this 15, 16, 17, 18, 19T range)
"to maintain roughly the same speed,
you only need to change cadence
by 5 rpm per gear step."
This reduces leg strain during shifting,
gives you wider options between pushing (low cadence)
or spinning (high cadence) to maintain a given speed—
that's the other kind of "easier."
Here, I'll draw out with arrows
the speed range of 15–17T at 90–100 rpm (red in the figure above)
and the speed range of 17–19T (blue in the figure)
within the cadence range.
With 16T added,
shifting changes from 15→17→15T
to 15→16→17→16→15T,
and with 18T added,
shifting changes from 17→19→17T
to 17→18→19→18→17T.
If you ask which gives bigger benefits,
at hobby racer speeds,
the latter seems more significant.
It's extremely rare for hobby racers to maintain
a solo flat cruising speed of nearly 40 km/h.
And if someone has the legs for that,
they probably wouldn't often choose the 50T outer anyway,
so I've calculated the table speeds for 50T.
Even with 50T, can you maintain
100 rpm on the 15T, say, for 30 minutes?
If not, there's no point making a table
for 52T or 54T speeds!
That's my reasoning.
So if someone said I could add either 16T or 18T
to an 11-speed sprocket with
11, 12, 13, 14, 15, 17, 19, 21, 24, 27, 30T teeth
to make a 12-speed sprocket,
the 18T would probably be more useful
for most people.
But because of the convention
"if you're filling in teeth, start from the top,"
the 18T isn't actually added in this scenario.
It's like in golf, where a 14-club limit forces you to carry
a difficult 3-wood that beginners can't use,
preventing you from including other useful clubs suited to your skill level.
Unlike golf club sets, sprockets don't offer freedom in configuration—
but that's inseparable from excellent shifting performance, so it can't be helped.
As for the doctrine-like devotion to sprockets
with just 5–6 clubs—putter, approach wedge, utility, 7-iron, 9-iron,
plus maybe one wood (→here)—
but there's more to the 18T story . . .
12-speed sprockets simply
don't have 18T!
Of course there may be exceptions, but
Shimano's 11–30T and 11–34T, and the 10-speed 11–36T,
SRAM's 10–28T (incidentally, 16T exists only in this tooth count),
10–30T, 10–33T, 10–36T,
and Campagnolo's micro-compact-ified
Super Record wireless (excluding the traditional 12-speed)
11–29T, 11–32T, and 11–34T—
across all major component makers' 12-speed sprockets,
there's no 18T option in any tooth count.
Campagnolo has three tooth options, and on all of them
the top eight cogs are
11, 12, 13, 14, 15, 16, 17, 19T,
so when pro riders cruise flats,
the feel is identical regardless of tooth count,
and they always have 16T without exception.
For top-tier pros, having a light 16T on the easy end
when cruising flats at 53–54T outer is handy;
12–16T is "easier" than 12–15T. In terms of the table above,
they're running different outer cogs and speed zones outside the table,
so whether 18T is available or not
isn't really a problem.
↑So this is the second use of this image in this article:
15–19T with no 16T or 18T.
15, 17, 19T gaps aren't even new to 9-speed—
even 6-speed sprockets achieved this 2T spacing.
The whole point of my argument is: this 2T spacing
can only be avoided in the current 12-speed lineups
by choosing the most cross-ratio (laugh) 11–30T,
so there's no way gear count increasing made things easier!
The current 12-speed does make climbing easier
with larger low gears,
but it hasn't made flat riding easier
in the 15–19T range on the outer cog,
with that ~40 km/h cruise speed.
By the way, if I change the outer from 50T
to 52T or 54T in the table above, the range becomes
more like ~40 km/h cruising rather than ~40 km/h cruising.
Also, whether 21T and beyond are spaced 2T or 3T apart
makes a huge difference.
The leg strain is completely different between
21–27T shifting as 21, 23, 25, 27T
versus 21, 24, 27T.
If a 28T low gear is enough,
I'd rather see 21T onward as
21, 24, 27, 30T (30T is uselessly light but unavoidable)
rather than
21, 23, 25, 28T (only the last is 3T spacing).
With 12-speed, you could realize
11, 12, 13, 14, 15, 16, 17, 19, 21, 23, 25, 28T,
and it would be hugely useful if they offered
a version with 28T removed and 18T inserted:
11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 23, 25T.
The micro-compact 10T top Super Record wireless
10–25T has this configuration minus 18T, plus 10T.
Hmm, so close.
Campagnolo's Gibli-exclusive 9-speed sprockets
11–19T and 11–21T—the former
is a full cross with consecutive natural numbers,
and Campagnolo's 10-speed junior-spec sprocket
that appeared only in Veloce grade
14–23T also has full-cross teeth.
If you use the 17, 18, 19, 20, 21, 22, 23T run in winter,
when you switch back to a normal sprocket in spring,
you get the feeling of "19, 21, 23, 25T? That's too many gaps!"
We're already in an era where some people
"have only ever owned and ridden disc-brake road bikes,"
and some of those fit that description
and race for a corporate team—
but such people probably don't find it weird
that disc road frames have different stiff points and balance
than rim-brake ones, or that they're harder to throw around.
They probably don't mind that the bar ends are heavy
or that bikes with brake hoses internally routed through bars and stems
have steering weight unique to that design.
So having a few low cogs spaced 3T or 4T at the end
just feels like "that's how it is,"
because they've got no reference point.
I'm not saying that's bad,
but as machinery gets more sophisticated, techniques get lost.
I think many people
"have never owned or ridden a mechanical-shifter road bike,"
and while that's not common, mechanical front derailleurs
are very reluctant to shift from inner to outer on uphill grades.
You have to stop pedaling once,
then stomp down hard all at once.
But electronic front derailleurs just brute-force it with motor power,
so that unweighting pedal technique isn't necessary.
So it's not bias—many people who've started road cycling recently
are actually pretty bad or careless about this point.
Though I haven't had zero chain drops in the last 20 years
(actually zero since entering 2024),
I've had no front-derailleur or front-shifting troubles.
Because I don't have a front derailleur installed.
↑You're probably thinking, "In 20 years,
you've also lost the unweighting front-shift pedal technique,"
which is fair.
But I can probably still do standing-pedal double-lever knee shifts.
↑Piling on another weird flex of having used drop-bar shifters,
which is the audacity.
Besides, knee-shifting is a useless technique that deserves to be forgotten anyway.