# 10 speed, 12-25 vs. 12-30



## Duane Behrens (Nov 8, 2013)

[Edit: This was formerly the "10-speed to 9-speed" thread, in which friends convinced me that changing the rear cassette was a better option than changing the chain rings. The conversation was interesting; I hope you'll give it a look. DB]

A friend asked me to post my reaction to replacing my original 12-25 cassette with a new 12-30 cassette. The bike: a Specialized Tarmac, standard Shimano 105/ 53-39 crank, Ultegra 12-25 cassette, Ultegra short-cage rear derailleur.

Mechanical: Surprisingly, the new cassette didn't require replacement of the chain. Even better, the original short-cage derailleur seems to work fine, with the B-screw set to near-full stop. 

Riding descents: I know it's my imagination - both cassettes have 12 teeth on their smallest cog - but the new cassette made me FEEL as if I was pedaling faster in the largest frong/smallest rear cog combination. In any case, I'm spending a lot more time on the larger front chain ring without getting into the 2 largest cogs in back. (I've gotten into the habit of glancing down at the cassette occasionally.)

Ascents: Well. I'm glad I didn't take the incremental step of switching to a 12-27; I'm not sure I would have noticed any difference. There is a noticeable - not huge - difference with the 12-30. I'm able to sit now through the steepest section of my normal climb more easily. I used to stand the entire way with the chain in the smallest front ring and the 5th largest cog in back. Now I'm able to just put it in the largest cog out back and spin up the hill.

Smoothness. It's really okay. I was afraid there would be missed or delayed shifts with the new wider spread, but I really haven't noticed that. I HAVE been careful to shift with a bit of authority. 

I would have been honest if this maiden voyage had been disappointing. But it was good, really. I'll keep it. Thanks to the posters over at the "10-speed to 9-speed" thread DB


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## aclinjury (Sep 12, 2011)

you selling your 12-25 cassette?


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## bike981 (Sep 14, 2010)

What's interesting (IMHO) is that the 12-25 are 12-30 are actually quite similar.

The listings I found for the Ultegra 12-25 and 12-30 have the cogs as listed below, which I've attempted to space out to show the same cogs matching up:


```
12-25 has:  12 13 14 15 16 17 19 21 23  25
  12-30 has:  12 13 14 15    17 19 21   24  27 30
```
They're identical for the first (smallest) 4 cogs, and almost identical after that, until you're on the 2 or 3 largest cogs.

In other words, the 12-30 only "kicks in" when you're in the 2 or 3 largest cogs. Other than those, the 12-30 is quite similar to the 12-25.


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## Duane Behrens (Nov 8, 2013)

bike981 said:


> What's interesting (IMHO) is that the 12-25 are 12-30 are actually quite similar.
> 
> The listings I found for the Ultegra 12-25 and 12-30 have the cogs as listed below, which I've attempted to space out to show the same cogs matching up:
> 
> ...


GREAT graph - THANKS!


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## Duane Behrens (Nov 8, 2013)

aclinjury said:


> you selling your 12-25 cassette?


Sure - make an offer. I think it's Ultegra also, and quite new, but I'll confirm prior to accepting or shipping. Thanks.


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## crit_boy (Aug 6, 2013)

A 12-30 with a 39 tooth chain ring. 

I want the cassettes to go the other way. I want a 12 or 13 small and 23 large. I dislike the large jumps. Remember the good old days when the goal was a straight block? I would like some of that back. 

The problem with the only kicking in at the larger cogs, is my usual hanging out between the 17 and 19 cogs. I would rather have the choice of 16-17-18-19-20-21-23 over 15-17-19-21-24-27-30. With the current compact cranks and mountain bike type cassettes, I guess I am in the minority.


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## Duane Behrens (Nov 8, 2013)

crit_boy said:


> A 12-30 with a 39 tooth chain ring.
> 
> I want the cassettes to go the other way. I want a 12 or 13 small and 23 large. I dislike the large jumps. Remember the good old days when the goal was a straight block? I would like some of that back.
> 
> The problem with the only kicking in at the larger cogs, is my usual hanging out between the 17 and 19 cogs. I would rather have the choice of 16-17-18-19-20-21-23 over 15-17-19-21-24-27-30. With the current compact cranks and mountain bike type cassettes, I guess I am in the minority.


Just to see where we've come in the last thirty years, I went out to the garage to count the teeth on a 1980 Nishiki restoration project. It's got 2 chain rings and a 6-speed rear sprocket. The results surprised me:

Chain rings: 52 x 40
Rear cogs: 14-16-18-20-22-28

So the front chain rings were pretty close to what we now call a "standard" (53 x 39). But 22 to 28 on the rear? That's a goodly jump, can't wait to see what that shift feels like! DB


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## tihsepa (Nov 27, 2008)

Duane Behrens said:


> Just to see where we've come in the last thirty years, I went out to the garage to count the teeth on a 1980 Nishiki restoration project. It's got 2 chain rings and a 6-speed rear sprocket. The results surprised me:
> 
> Chain rings: 52 x 40
> Rear cogs: 14-16-18-20-22-28
> ...


The people on bikes have gotten old and soft.
Well, except on the internet. They got faster and better looking, with bigger........... Well, nevermind.


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## skitorski (Dec 4, 2012)

tihsepa said:


> The people on bikes have gotten old and soft.
> Well, except on the internet. They got faster and better looking, with bigger........... Well, nevermind.


Easy there sailor  Whatever floats your boat, eh ? If the difference between a 25 and a 28 cassette is standing or sitting on a hill, I'll take the 28, 30 or 32 tooth every time. That's just me, older, softer, except I have gotten thinner and harder.

You riding today ? It's still in the 20's here at 8:00 am.


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## bradkay (Nov 5, 2013)

Duane Behrens said:


> Just to see where we've come in the last thirty years, I went out to the garage to count the teeth on a 1980 Nishiki restoration project. It's got 2 chain rings and a 6-speed rear sprocket. The results surprised me:
> 
> Chain rings: 52 x 40
> Rear cogs: 14-16-18-20-22-28
> ...


Wow, Duane, that's a crappy transition to the lowest gear. I am not sure that an early 1980s rear derailleur will do that in a smooth fashion. If you can find one, I think that the following setup would shift better:

14-16-18-21-24-28

I am also surprised that your short cage Ultegra derailleur is handling that 30t cog in the back. 

CritBoy, your preference is fine for flatter areas, but most of us would prefer a wider range of gears in hill country. There's something about spinning that keeps our knees working better... I'm not as strong as Duane, so I am using a compact crank and a 12-27 10sp setup these days (or a 26-36-48 triple and a 12-25 9sp on my Klein).


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## tihsepa (Nov 27, 2008)

skitorski said:


> Easy there sailor  Whatever floats your boat, eh ? If the difference between a 25 and a 28 cassette is standing or sitting on a hill, I'll take the 28, 30 or 32 tooth every time. That's just me, older, softer, except I have gotten thinner and harder.
> 
> You riding today ? It's still in the 20's here at 8:00 am.



Yep, it was cold and snowing. I was the only bike out there. Rode 40 miles on the MUT.


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## tihsepa (Nov 27, 2008)

skitorski said:


> Easy there sailor  Whatever floats your boat, eh ? If the difference between a 25 and a 28 cassette is standing or sitting on a hill, I'll take the 28, 30 or 32 tooth every time. That's just me, older, softer, except I have gotten thinner and harder.
> 
> You riding today ? It's still in the 20's here at 8:00 am.


My point was that guys used to ride bikes with 5 or less gears out back and climbed hills using a 42-23. Those guys are older and are now spinning a mountain cassette with a compact crank. 
No offense intended.


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## skitorski (Dec 4, 2012)

If you rode in that pic shown above, nothing I can throw at you will hurt :thumbsup:

22 miles for me and it felt like 100. Oh, the temp roe into the 50's by noon.  I rode back in the 70's. An original Windsor. Hecho in Mexico, with Suntour and dia compe. 2x in front, 5x in back. Sew-ups. But all flat along the strand on the Beach in Los Angeles where I lived. Never really appreciated gears because I never really needed them.


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## tihsepa (Nov 27, 2008)

skitorski said:


> If you rode in that pic shown above, nothing I can throw at you will hurt :thumbsup:


Just me and the cross country skiers.


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## Duane Behrens (Nov 8, 2013)

bradkay said:


> Wow, Duane, that's a crappy transition to the lowest gear. I am not sure that an early 1980s rear derailleur will do that in a smooth fashion. If you can find one, I think that the following setup would shift better:
> 
> 14-16-18-21-24-28
> 
> ...


The sprocket that was on the [1980 Nishiki] bike when I bought it is identified on the back side as a Shimano. I'm not sure Shimano sprocket/hub assemblies were OEM on a 1980 Nishiki, so this might have been an aftermarket piece. But I like your suggested alternative, and I WILL look for it. Thanks much.


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## skitorski (Dec 4, 2012)

bike981 said:


> 12-25 has: 12 13 14 15 16 17 19 21 23 25
> 12-30 has: 12 13 14 15 17 19 21 24 27 30


Arggh. My 8-sp is 11 13 15 18 21 24 28 32

Wide ratio and covers everything but now I know what the 12, 14 and maybe a 16 tooth are. I was on flat ground in a group ride yesterday, and their speed fell right in my gap half the time. Never noticed it as my previous rides are all up/down and solo. They were at 16-18 and I fell into around 15-16 mph, 22/23.6 kph.


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## tihsepa (Nov 27, 2008)

We have no real hills here in the midwest. I have a friend that rides a 15-25 with a standard crank. I have been keeping my eyes open for a used jr. cassette. Just to give it a shot.


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## Duane Behrens (Nov 8, 2013)

bike981 said:


> What's interesting (IMHO) is that the 12-25 are 12-30 are actually quite similar. The listings I found for the Ultegra 12-25 and 12-30 have the cogs as listed below, which I've attempted to space out to show the same cogs matching up:
> 
> 
> ```
> ...


Again - your graph was so helpful in understanding the difference between the two. Having ridden with the new cassette for a week now, I'm already wishing the small gaps were on the large cogs rather than the smaller. (We do mostly hills around here.) In other words, the following sprocket size sequence would be preferred: 12-15-18-21-24-26-27-28-29-30.

Is there anyway to go about achieving the above? Thanks. DB


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## den bakker (Nov 13, 2004)

Duane Behrens said:


> Again - your graph was so helpful in understanding the difference between the two. Having ridden with the new cassette for a week now, I'm already wishing the small gaps were on the large cogs rather than the smaller. (We do mostly hills around here.) In other words, the following sprocket size sequence would be preferred: 12-15-18-21-24-26-27-28-29-30.
> 
> 
> Is there anyway to go about achieving the above? Thanks. DB


3-4% difference between the large sprockets and 20% at the small sprockets? curious gearing indeed.


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## mtsheron (Jul 16, 2012)

The new gearing of the largest cog at 30 will do that. Will make climbing easier as well! Great if your weak in climbing and need the assistance. My Orca came with a 32! Man that thing was like I was free wheeling nothing but air. Went back to a 11-26 cassette and like it better.


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## AlanE (Jan 22, 2002)

I would have gone with an 11-28 cassette rather than 12-30. That would have expanded your gearing at both ends.


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## Duane Behrens (Nov 8, 2013)

den bakker said:


> 3-4% difference between the large sprockets and 20% at the small sprockets? curious gearing indeed.


I agree. It only makes sense if you spend 90% of your time and energy on moderate to steep hills, as I do. There, those small gaps in the larger cogs make sense. Thanks


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## den bakker (Nov 13, 2004)

Duane Behrens said:


> I agree. It only makes sense if you spend 90% of your time and energy on moderate to steep hills, as I do. There, those small gaps in the larger cogs make sense. Thanks


I guess all the people living in mountains got it wrong for so long.  
what do you plan to do: change gear every time the grade changes from 7% to 7.3% and then double shift if it turns to 6.7% immediately after?


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## Duane Behrens (Nov 8, 2013)

den bakker said:


> I guess all the people living in mountains got it wrong for so long.
> what do you plan to do: change gear every time the grade changes from 7% to 7.3% and then double shift if it turns to 6.7% immediately after?



12-25 has: 12 13 14 15 16 17 19 21 23 25 
12-30 has: 12 13 14 15 17 19 21 24 27 30 
[reposted above with thanks to "Bike981"]

I merely want to reduce the current, 3-tooth gaps in the easier (larger) cogs of the new 12-30 cassette. Reason: There are numerous, constant, long grades in our area where spinning at a comfortable rate would be better achieved with a closer ratio.


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## den bakker (Nov 13, 2004)

Duane Behrens said:


> 12-25 has: 12 13 14 15 16 17 19 21 23 25
> 12-30 has: 12 13 14 15 17 19 21 24 27 30
> [reposted above with thanks to "Bike981"]
> 
> I merely want to reduce the current, 3-tooth gaps in the easier (larger) cogs of the new 12-30 cassette. Reason: There are numerous, constant, long grades in our area where spinning at a comfortable rate would be better achieved with a closer ratio.


yes I understood your intend the first time, does not mean it makes sense. 
Anyway, Miche is the company that will take your money. they sell separate cogs. For the high end, no one makes the low end you want. at least mostly,


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## crossracer (Jun 21, 2004)

I've done this and like it a lot. A 12-32 with a mtn bike rear der and a 53-39 up front. 
Yes there are jumps, can't help that. 

But boy I like the ability to stay in the big gear so much longer going up
Hills. 

Bill


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## Duane Behrens (Nov 8, 2013)

crossracer said:


> I've done this and like it a lot. A 12-32 with a mtn bike rear der and a 53-39 up front.
> Yes there are jumps, can't help that.
> 
> But boy I like the ability to stay in the big gear so much longer going up
> ...


Very close to the 53/39 and 12/30 I'm running currently. Guess I'll live with the jumps. I DO like it better than the original 12/25. Thanks.


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## crossracer (Jun 21, 2004)

Duane Behrens said:


> Very close to the 53/39 and 12/30 I'm running currently. Guess I'll live with the jumps. I DO like it better than the original 12/25. Thanks.


Since I have short steep hills where I live it isn't like I'm climbing for hours at a time. 

Finally my only proof is that every PR I set this year on Strava in the hills was with this setup. 


Bill


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## Duane Behrens (Nov 8, 2013)

AlanE said:


> I would have gone with an 11-28 cassette rather than 12-30. That would have expanded your gearing at both ends.


Hi, Alan. Not sure I agree with you. Running front chain rings of 53/39, I didn't really need another smaller cog. My wife runs a 50/34 up front and an 11/28 cassette in back. When we're both climbing steep - her in 34 front/28 back, and me in 39 front/30 back - she's pedaling slightly faster than me. I'm a bit stronger in the legs, so it seems about right. Thanks.


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## Duane Behrens (Nov 8, 2013)

den bakker said:


> yes I understood your intend the first time, does not mean it makes sense.
> Anyway, Miche is the company that will take your money. they sell separate cogs. For the high end, no one makes the low end you want. at least mostly,


I'll look them up. Thank you for your polite responses.


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## JCavilia (Sep 12, 2005)

Duane Behrens said:


> Just to see where we've come in the last thirty years, I went out to the garage to count the teeth on a 1980 Nishiki restoration project. It's got 2 chain rings and a 6-speed rear sprocket. The results surprised me:
> 
> Chain rings: 52 x 40
> Rear cogs: 14-16-18-20-22-28
> ...


Setups like that were very common in the days of 5 and 6-speed freewheels. 4 or 5 cogs fairly closely spaced for most riding, and one much bigger cog - a "bailout" gear for the steepest bits. Sometimes called "Alpine" gearing, it was sometimes even more extreme than your example. Shimano still makes them, including a 14-15-18-21-24-34.

They work fine. You just accept that the last shift will be a big jump, not to precisely tune cadence but to help you get up the hardest bits. It seems strange if you began riding in the days of 9, 10 or 11-speed, but it works.

And 52-40, or even 52-42, were the most common ring combinations until at least the late 80's.


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## den bakker (Nov 13, 2004)

JCavilia said:


> .
> 
> And 52-40, or even 52-42, were the most common ring combinations until at least the late 80's.


53/42 as well. 
not without reason.


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