Road Cycling - Gearing question-road bikes

How do you figure out comparable gearing?
For example;
does a 53x12 = 52x11?
39x23 = 42x26?

I guess I'm asking if 1 tooth off the chainrings is the same as 1 tooth off the rear cogs.

I'm a dummy with this stuff so thanks in advance

This doesn't exactly answer your question ... but it's quite cool anyway!

http://www.arachnoid.com/bike/

I guess I'm asking if 1 tooth off the chainrings is the same as 1 tooth off the rear cogs.No....
It's best to just convert your gearing combos into gear inches and work from there.......
Gear inches = #chainring divided by #cog and multiply that number by 27.

George

Why dontcha' go here (http://www.sheldonbrown.com/gears/) and plug in a few numbers?

SteveE

ok thanks. That link is pretty cool too

Here is the one I use -

www.panix.com/~jbarrm/cycal/cycal.30f.htm

It gives you all you will need (except a degree in physics to make sense of it).

Now that you have all that information, it has been my experience that you will find what gears work best for you by good old trial and error! What ultimately works best for you is what you should use. Some pepole feel fine jumping up two or four teeth on the cassette while others do best with closer gear changes. Ultimately this will also give you some idea about what cassette will work best for you and your style of riding.

So much for my pontificating!!

Bill

It seems on the surface that it would work out to be the same but 52/11 = 4.72 and 53/12 = 4.42. The number closer to 1 is easier to push. If you think about say a triple set up with a 30 chain ring and a 30 rear cog that ratio is 30/30=1 and is very easy to push. raising the tooth count up front to say a 32 now 32/30 is some number greater than 1 and harder to push...

It's a matter of ratios. To get the "equivalent" chainring for a cog change, multiply the gear ratio by the new cog size.

Example: 53/12*11 = 48.6

So the closest gear to a 53/12 using an 11T cog is 49/11.

To get the "equivalent" cog for a chainring change, divide the new chainring size by the gear ratio.

Example: 42/(39/23) = 24.8

So the closest gear to a 39/23 usnig a 42T chainring is 42/25

It seems on the surface that it would work out to be the same but 52/11 = 4.72 and 53/12 = 4.42. ....and factor in the actual wheel diameter, then you'll get 128 and 119 gear inches, respectively......which is a noticable difference.

George

Here is the one I use -

www.panix.com/~jbarrm/cycal/cycal.30f.htm



Bill

Link doesn't work

Add an l to the URL: http://www.panix.com/~jbarrm/cycal/cycal.30f.html

....and factor in the actual wheel diameter, then you'll get 128 and 119 gear inches, respectively......which is a noticable difference.

George

So that means for every rotation of the wheel you go 9 inches farther with the 52x11 compared to the 53x12? Is that right?

I did this a few weeks ago and found it useful. It was relatively easy with Excel.

link here (http://www.bikeforums.net/showthread.php?t=46829)

-mark

[QUOTE=RacerX]So that means for every rotation of the wheel you go 9 inches farther with the 52x11 compared to the 53x12? Is that right?[/QUOTE

.....should read... 'for every rotation of the crank'.....