Gear Ratios 1 x 9

[The Drongo]

So, I am not a mathematician, therefore need some input.

 

Am going to go for a 1x9 setup, and was advised to run 36 front and 12/36 rear. But I ran some numbers based on the Radius Ratio, of dividing wheel radius by crank length (26 inch in this instance with 175mm cranks) and apparently:

 

Running a 34 - 11/34 will give you more revolutions per, than running a 36 - 12/36 will, in all gears but 4&9 which are equal, and 5&6 where the + is as little as 0.03 and 0.05 revolutions over the same gears in 11/34.

 

So, same torque applied, 34 -11/34 will outroll 36 - 12/36,...

 

COMMENTS??

[The Drongo]

Speak up disciples of crank!

[deanbean]

Drongo is it for a mtb. I used one over the Xmas break, on the southern wild coast, and found that a 36x11-34 was OK for all but the steepest climbs.

Maths = .

What chain keeper are you using btw, as the chain will jump off without one.

 

Oja, I'm not the strongest climber, if I was stronger I would have been OK on the climbs.

 

Ha sorry, I see what you're asking (long day and all that) If you're strong and light you should handle the hills on the 36x24, then the 36x11 is quicker. Id go with the 36 and 11x34. you can walk faster if you have to get off the bike to push.

Edited March 14, 2011 by deanbean

[Shebeen]

you need to start playing with

 

rabbit

Edited March 14, 2011 by SteveCT

[The Drongo]

Drongo is it for a mtb. I used one over the Xmas break, on the southern wild coast, and found that a 36x11-34 was OK for all but the steepest climbs.

Maths = .

What chain keeper are you using btw, as the chain will jump off without one.

 

Oja, I'm not the strongest climber, if I was stronger I would have been OK on the climbs.

 

Thank you!!

 

Yes MTB. I left the religion of ROAD when they began to get fundamentalist!

 

36 - 11/34 sheesh brother, I'm not surprised you battled with the climbs! That is also not going to give you the ideal change ratio to my mind.

 

My spreadsheet (which I will post after comment) seems to indicate that for hilly a 34- 11/34 would be good - better than 36 - 12/36 which is a 1:1 change ratio.

 

(Modified e-thirteen DRS with an Aerozine alu. jockey wheel.)

[The Drongo]

you need to start playing with

 

rabbit

 

Dunnit - TA.

 

But now I seek the comment of the Disciples of Crank. You good???

[Aurora]

I use a 40 with a 11-32 cassette

[deanbean]

I use a 40 with a 11-32 cassette

 

I would kill myself trying to push that gear.

[The Drongo]

I use a 40 with a 11-32 cassette

 

Hmmm

 

I bow to you sir - entirely dependant on where you lives tho!

[Aurora]

KZN, that ratio has made it up the steepest hills that its been thrown including karkloof

[Wyatt Earp]

Personally I will sette for a 40 with an 11-34.

Go with a 36 and 11-34 that will get you through anything .

I did Attakwas on a 33/18 and survived.

Edited March 14, 2011 by Dangle

[DirtyFrank]

So, I am not a mathematician, therefore need some input.

 

Am going to go for a 1x9 setup, and was advised to run 36 front and 12/36 rear. But I ran some numbers based on the Radius Ratio, of dividing wheel radius by crank length (26 inch in this instance with 175mm cranks) and apparently:

 

Running a 34 - 11/34 will give you more revolutions per, than running a 36 - 12/36 will, in all gears but 4&9 which are equal, and 5&6 where the + is as little as 0.03 and 0.05 revolutions over the same gears in 11/34.

 

So, same torque applied, 34 -11/34 will outroll 36 - 12/36,...

 

COMMENTS??

 

You are right but we are only talking a 3% difference so I doubt whether you`ll notice. This gear calculator is handy.

 

http://www.sheldonbrown.com/gears/

[Johan Bornman]

So, I am not a mathematician, therefore need some input.

 

Am going to go for a 1x9 setup, and was advised to run 36 front and 12/36 rear. But I ran some numbers based on the Radius Ratio, of dividing wheel radius by crank length (26 inch in this instance with 175mm cranks) and apparently:

 

Running a 34 - 11/34 will give you more revolutions per, than running a 36 - 12/36 will, in all gears but 4&9 which are equal, and 5&6 where the + is as little as 0.03 and 0.05 revolutions over the same gears in 11/34.

 

So, same torque applied, 34 -11/34 will outroll 36 - 12/36,...

 

COMMENTS??

 

You are making it too difficult for yourself.

 

Ignore the wheel circumference unless you are comparing two diffent bikes with different wheels.

 

Simply divide the chainring by the sprocket. In other words, 39 / 13 = 3

 

This means three wheel revolutions per crank revolution.

 

Now to compare another setup - a 42 chainring example.

 

42 / 12 = 3.5

 

Thus, the last example will make you faster, but you need to work harder.

 

If you want to know how much faster - 4.5 - 4 = 0.5 wheel revolutions per crank revolution faster.

[The Drongo]

KZN, that ratio has made it up the steepest hills that its been thrown including karkloof

 

Then I bow to you SIR!

 

Particularly if you have pettaled it up - THE MINESHAFT.....

 

.....Still bowing - 'we're not worthy' style.

 

Methinks I will give the actual a miss, will run the numbers for interests sake.

[The Drongo]

You are right but we are only talking a 3% difference so I doubt whether you`ll notice. This gear calculator is handy.

 

http://www.sheldonbrown.com/gears/

 

Thank you sir - dunnit.

 

I feel, with all due respect to Johan's post, that this is a more accurate method of calculating and it is the method I have used in the past.

[The Drongo]

Personally I will sette for a 40 with an 11-34.

Go with a 36 and 11-34 that will get you through anything .

I did Attakwas on a 33/18 and survived.

 

Yep.

 

36 - 11/34 is what I have pegged. Like to bomb the downhills so need some extra crankability in the high gears.

 

Will give the 40 a miss for now, until I get fitter and younger.