9 speed cassette: 12-36. Too spaced out for front double?

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reohn2
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Re: 9 speed cassette: 12-36. Too spaced out for front double?

Postby reohn2 » 1 Jan 2019, 6:42pm

CJ wrote:I've used this 12-36 9-speed cassette with a genuinely compact double (42,22) on my touring bike these past three years and find it absolutely spiffing!

Don't worry about the cassette being too widely spaced, or take any notice of those hyper-sensitive souls who opine that it is. I've ridden behind and studied the gearing use of people who advocate closely spaced gears and they don't shift any more often than I do. Rather than use the fine tuning as they claim, to maintain a constant cadence, what they actually seem to want this for is a closely-spaced selection of 'just right' gears frrom which they hope to select one that is not too low for the flat or too high to power up moderate slopes! Not a clever way to use gears IMO.

Other people have other opinions :wink:
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531colin
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Re: 9 speed cassette: 12-36. Too spaced out for front double?

Postby 531colin » 1 Jan 2019, 8:15pm

reohn2 wrote:
CJ wrote:I've used this 12-36 9-speed cassette with a genuinely compact double (42,22) on my touring bike these past three years and find it absolutely spiffing!

Don't worry about the cassette being too widely spaced, or take any notice of those hyper-sensitive souls who opine that it is. I've ridden behind and studied the gearing use of people who advocate closely spaced gears and they don't shift any more often than I do. Rather than use the fine tuning as they claim, to maintain a constant cadence, what they actually seem to want this for is a closely-spaced selection of 'just right' gears frrom which they hope to select one that is not too low for the flat or too high to power up moderate slopes! Not a clever way to use gears IMO.

Other people have other opinions :wink:


No no, R2, its there in black and white, you and me are doing it wrong, mate.
Funnily enough, he has never ridden behind me, unless he got that "cloak of invisibility" thing he was fiddling with working as well as his gears. :lol:

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Re: 9 speed cassette: 12-36. Too spaced out for front double?

Postby Bmblbzzz » 1 Jan 2019, 8:21pm

CJ wrote:I've used this 12-36 9-speed cassette with a genuinely compact double (42,22) on my touring bike these past three years and find it absolutely spiffing!

Hmmm... faint bell rings. Your touring bike isn't a Salsa Fargo by any chance is it?

Brucey
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Re: 9 speed cassette: 12-36. Too spaced out for front double?

Postby Brucey » 1 Jan 2019, 8:41pm

CJ's gearing setup is compared with the OP's (same cassette, different chainset) here

http://ritzelrechner.de/?GR=DERS&KB=32,48&RZ=12,14,16,18,21,24,28,32,36&UF=2150&TF=90&SL=2.6&UN=MPH&DV=gearInches&GR2=DERS&KB2=22,42&RZ2=12,14,16,18,21,24,28,32,36&UF2=2150

as it happens the 18,21 interval in the cassette would trouble me less with CJ's chainset. The large gaps in the gears basically occur in those parts of the gear range that you might use when you are already climbing, when slightly larger gaps in the ratios are better tolerated.

Also note that no-one has mentioned the 24,28 interval in this cassette, even though it is an identical percentage gap as the 18,21. I suspect that the reason for this is that it rarely results in a 'problem' gap in the ratios regardless of the chainset you use; they are always gears you might only ever use when climbing.

cheers
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CJ
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Re: 9 speed cassette: 12-36. Too spaced out for front double?

Postby CJ » 2 Jan 2019, 11:34am

Bmblbzzz wrote:Hmmm... faint bell rings. Your touring bike isn't a Salsa Fargo by any chance is it?

No, SPA Ti Tourer, Middleburn cranks with Incy spider. Shifting by Campag 10s Ergopower and modified Shimano 9s MTB mech.
Chris Juden
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Re: 9 speed cassette: 12-36. Too spaced out for front double?

Postby Bmblbzzz » 2 Jan 2019, 2:14pm

CJ wrote:
Bmblbzzz wrote:Hmmm... faint bell rings. Your touring bike isn't a Salsa Fargo by any chance is it?

No, SPA Ti Tourer, Middleburn cranks with Incy spider. Shifting by Campag 10s Ergopower and modified Shimano 9s MTB mech.

Ah, Shimmergo! Used to hear a lot about that, but that's the first time I've heard of it for a year or more, I think.

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CJ
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Re: 9 speed cassette: 12-36. Too spaced out for front double?

Postby CJ » 2 Jan 2019, 2:22pm

reohn2 wrote:
CJ wrote:I've used this 12-36 9-speed cassette with a genuinely compact double (42,22) on my touring bike these past three years and find it absolutely spiffing!

Don't worry about the cassette being too widely spaced, or take any notice of those hyper-sensitive souls who opine that it is. I've ridden behind and studied the gearing use of people who advocate closely spaced gears and they don't shift any more often than I do. Rather than use the fine tuning as they claim, to maintain a constant cadence, what they actually seem to want this for is a closely-spaced selection of 'just right' gears frrom which they hope to select one that is not too low for the flat or too high to power up moderate slopes! Not a clever way to use gears IMO.

Other people have other opinions :wink:

Opinions are fine for those who hold 'em, but unless they stand up to rational analysis, opinions should not be promoted to the rank of general recommendations.

The opinion that a 17% jump in gear ratio is a 'problem' fails this test because if it were, single-speed would be useless.

I can justify my opinion that it is not a problem by referring to several data published in the book 'Bicycling Science', which indicate that the power/rpm curves of a typical human engine have a peak that is quite broad and flat, such that variations in cadence as great as 10% either side of the optimum (the effect of a 20% gear interval) should not affect power by more than one or two percentage points.

That may be enough to concern a racer perhaps, but should not bother the rest of us, who are not so much concerned to maximise power as to minimise effort and fatigue. The relative insignificance of the more easily measurable power/cadence relationship however, combined with the fact that we can quite easily and comfortably pedal a GREAT DEAL faster or slower, only goes to show that the 'problem' of gaps between gears is psychological rather than physical.
Chris Juden
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RickH
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Re: 9 speed cassette: 12-36. Too spaced out for front double?

Postby RickH » 2 Jan 2019, 2:48pm

BITD I would have said that big gear gaps bothered me. Getting used to running an Alfine 8 IGH (on a Circe Helios tandem) pretty much cured me of that with its big jump in the middle of its range (4-5?)!

Now I'm riding a 12-36 9 speed (admittedly in the middle of a frivolous 10-42 11 speed 1x - 10-12-14-16-18-21-24-28-32-36-42 :lol: ) I can only think of 1 occasion, in 2 years & nearly 3,500 miles, when I felt I didn't have quite the right gear & that was only for about 1/4 mile until the gradient of the road changed again.

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Chris Jeggo
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Re: 9 speed cassette: 12-36. Too spaced out for front double?

Postby Chris Jeggo » 2 Jan 2019, 3:58pm

CJ wrote: ... I've ridden behind and studied the gearing use of people who advocate closely spaced gears and they don't shift any more often than I do. Rather than use the fine tuning as they claim, to maintain a constant cadence, what they actually seem to want this for is a closely-spaced selection of 'just right' gears frrom which they hope to select one that is not too low for the flat or too high to power up moderate slopes! ...

CJ wrote: ... referring to several data published in the book 'Bicycling Science', which indicate that the power/rpm curves of a typical human engine have a peak that is quite broad and flat, such that variations in cadence as great as 10% either side of the optimum (the effect of a 20% gear interval) should not affect power by more than one or two percentage points. ...

One could regard this +/- 10% band of acceptable cadence in this way: an 18t sprocket covers a band of road conditions (for a given rider power output) corresponding to 'ideal' sprockets ranging from 16.2 teeth to 19.8 teeth, were such things possible, while a 21t sprocket has an 'acceptable band' from 18.9t to 23.1t. So, there's a quite narrow overlap between the acceptable bands of 18t and 21t sprockets. With a more closely spaced cassette there's more overlap everywhere, still taking +/- 10% as the acceptable band. So while a rider who seeks always to be in the optimum sprocket of a narrow-spaced cassette will change gear more often than one with a wider-spaced cassette, as road conditions fluctuate, a rider who seeks always to be in an acceptable band of a narrow-spaced cassette might well change gear less often than one with a wider-spaced cassette.

That's just another way of thinking about the issue. We're all different in our wishes for how many gears, covering what range, how many chainrings, how much more disruptive are front changes than rear ones, and what steps are too large, or too small. My Airnimal came with a 9-speed 12-27t cassette and I found some of the steps between gears so small that I nearly always changed two at a time, so now I have an 11-32t cassette on it.

reohn2
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Re: 9 speed cassette: 12-36. Too spaced out for front double?

Postby reohn2 » 2 Jan 2019, 5:26pm

CJ wrote:
reohn2 wrote:
CJ wrote:I've used this 12-36 9-speed cassette with a genuinely compact double (42,22) on my touring bike these past three years and find it absolutely spiffing!

Don't worry about the cassette being too widely spaced, or take any notice of those hyper-sensitive souls who opine that it is. I've ridden behind and studied the gearing use of people who advocate closely spaced gears and they don't shift any more often than I do. Rather than use the fine tuning as they claim, to maintain a constant cadence, what they actually seem to want this for is a closely-spaced selection of 'just right' gears frrom which they hope to select one that is not too low for the flat or too high to power up moderate slopes! Not a clever way to use gears IMO.

Other people have other opinions :wink:

Opinions are fine for those who hold 'em, but unless they stand up to rational analysis, opinions should not be promoted to the rank of general recommendations.

The opinion that a 17% jump in gear ratio is a 'problem' fails this test because if it were, single-speed would be useless.

I can justify my opinion that it is not a problem by referring to several data published in the book 'Bicycling Science', which indicate that the power/rpm curves of a typical human engine have a peak that is quite broad and flat, such that variations in cadence as great as 10% either side of the optimum (the effect of a 20% gear interval) should not affect power by more than one or two percentage points.

That may be enough to concern a racer perhaps, but should not bother the rest of us, who are not so much concerned to maximise power as to minimise effort and fatigue. The relative insignificance of the more easily measurable power/cadence relationship however, combined with the fact that we can quite easily and comfortably pedal a GREAT DEAL faster or slower, only goes to show that the 'problem' of gaps between gears is psychological rather than physical.

My opinion is valid because the gap from 18t to 21t in the middle of the cruising range bothers my cadence/power range,I find a 19 to 21 gap ideal.
To elaborate,my 9sp cassettes are 14,15,17,19,21,23,25,28,32 or 26,30,34 with an Alpine double of 24-39t.The top end is high enough and the bottom end is low enough,but it's the intermediate higher end 15,17,19,21,23 cogs I use most,the gaps work well for me,anything wider doesn't anything closer doesn't,and I don't ride a loaded bike any more just day luggage.
I don't race,never have done and never will,but I know what gaps feel like and I'm not alone in that,nor am I claiming I'm right and you're wrong simply I prefer what I prefer.
I've tried the standard cassette and don't get on with it,that's why I make up the cassettes that suit me,all the science won't convince me otherwise when I know what suites me.
Your preferences suit you and I have no problem with that,but please don't try and tell I'm wrong when my legs tell me otherwise.
Last edited by reohn2 on 2 Jan 2019, 5:47pm, edited 2 times in total.
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reohn2
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Re: 9 speed cassette: 12-36. Too spaced out for front double?

Postby reohn2 » 2 Jan 2019, 5:39pm

Chris Jeggo wrote:........... We're all different in our wishes for how many gears, covering what range, how many chainrings, how much more disruptive are front changes than rear ones, and what steps are too large, or too small........


Exactly.
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Brucey
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Re: 9 speed cassette: 12-36. Too spaced out for front double?

Postby Brucey » 2 Jan 2019, 7:02pm

larger gear gaps rarely trouble me when climbing; I am usually quite prepared to push a bit hard for a while or ride easy for a bit if needs be. The gradient will soon change again and I will need a different plan and/or a different gear. However when tapping along on flatter roads a large gear gap in the wrong place can (by comparison) drive me crackers.

So for example it might be OK without, but with a load on, a set of gears that jumps from about 61" to about 72" (with nothing inbetween) would be likely to earn my ire. For others they may have different needs and different things that they are and are not willing to ride around.

Is my particular quirk that unusual?

cheers
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reohn2
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Re: 9 speed cassette: 12-36. Too spaced out for front double?

Postby reohn2 » 2 Jan 2019, 7:19pm

Brucey wrote:........Is my particular quirk that unusual?

cheers

Not IMO
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Samuel D
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Re: 9 speed cassette: 12-36. Too spaced out for front double?

Postby Samuel D » 2 Jan 2019, 11:02pm

Brucey wrote:Is my particular quirk that unusual?

No, and I think there’s another reason on top of those you cite: while on the flat in contrast to climbing, power is mainly used to overcome aerodynamic drag that varies with the square of the speed; consequently, small changes in speed greatly change the power requirement, and so closer ratios are needed to stay in a desired power window than on climbs where power goes about linearly with speed.

We prefer closer ratios into a headwind for the same reason and the additional one that it’s human nature to push nearer one’s limit in that circumstance.

That said, I agree with Chris Juden that close ratios are often not used sensibly and by extension often not needed. I sometimes do hard, fast group rides and even for this I find 2-tooth gaps close enough whereas some of my companions prefer 1T gaps wherever possible. For touring I wouldn’t care about 3T gaps. Feelings about optimum cadence are quite different from measurable performance.

On the last point, I have a friend I can barely keep up with on climbs. When I run out of low gears, which I do before him … nothing appears to change. Sure, I’d badly like a lower gear, but as far as I can tell I climb at my limit at about the same speed without it. And here I’m talking about a terribly ‘wrong’ cadence, like 60 RPM.

Of course I’m out of the saddle in these cases. Seated climbing is a whole different thing for reasons I haven’t fully worked out.

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Re: 9 speed cassette: 12-36. Too spaced out for front double?

Postby Bmblbzzz » 3 Jan 2019, 8:40pm

Samuel D wrote:We prefer closer ratios into a headwind for the same reason and the additional one that it’s human nature to push nearer one’s limit in that circumstance.

It's a minor point, but I disagree with your 'human nature' comment. For me at least, I'm more willing to push myself when climbing than into a headwind. Perhaps because I know that every climb has a top, promising a rest when you get there, whereas headwinds last for an unknown length of time, or perhaps because I'm better (more accurately, less bad) at climbing than at pushing into a headwind. Whatever the reason, I'd say that human nature in this respect is probably as varied as when it comes to gearing.