Singlespeed & Fixed Gear - gear inch conversion

I am running a 48/16 on a 26 inch rear wheel.
Can anyone tell me how much bigger the resulting
gear would be if I ran the same on a 700c wheel.
Thanks. DanO

These numbers won't be exact but will give you an idea between two wheel diameters...

48 / 16 x 26 = 78 gear inches
48 / 16 x 27 = 81 gear inches

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

You can keep pretty much the same gear if you fit a 46t chainring. A 17t cog (and 48t ring) would give you a slightly easier gear.

you really need the true tire diameter. a 26x1"slick is much smaller than a 26x2.35 knobie. Likewise, a 700cx20 tire is much smaller than a 700cx38.

Precisely measure the true tire diameter (while loaded), use the fixxer's formula, your good to go.

I was looking on Rohloff's site the other day (sorry, gears, I know we're not allowed :) ), and their formula said to use the circumfurance of the wheel, which surely makes more sense. Aren't gear inches defined as the distance travelled for one complete revolution of the cranks? I always thought it was the diameter, but being a maths geek, it got me thinking :S

"and their formula said to use the circumfurance of the wheel, which surely makes more sense"


That would be development... we covered this the other day (surely someone here knows which thread)

"Aren't gear inches defined as the distance travelled for one complete revolution of the cranks? " No gear inches represent the size of your pennyfarthing. Development is defined as the distance travelled. Gear inches is really meaningless to most people born since the invention of the safety.

I was looking on Rohloff's site the other day (sorry, gears, I know we're not allowed :) ), and their formula said to use the circumfurance of the wheel, which surely makes more sense. Aren't gear inches defined as the distance travelled for one complete revolution of the cranks? I always thought it was the diameter, but being a maths geek, it got me thinking :S

It doesn't matter..... one can easily derive circumference from a given diameter of a wheel. It's so much faster & easier to measure diameter and use it as a variable.

"It's so much faster & easier to measure diameter and use it as a variable."

True, easier and faster to measure diameter, but more accurate to measure rolling circumference then weighted diameter. Then, obviously, it would be no problem to determine your true weighted diameter.

True, easier and faster to measure diameter, but more accurate to measure rolling circumference then weighted diameter. Then, obviously, it would be no problem to determine your true weighted diameter.

Yes, agreed.

Sure you can use diameter or circumference to compare different gears on different bikes, but as for the matter of defining gear inches, is diameter correct (assuming using circumference is inches developement)?

Sorry, i'm a maths geek, I like to define things :)

.yes.

I can't believe you guys are all so off base!!! Every last one of you has failed to define the three most important factors in structuring a mathematical formula to determine pedalling effort/efficiency... Theta, Delta, and Mu...

Where:
Theta is defined as = You all have been arguing about this same stuff for years
Delta is the reverse inverse of = I'm sick of hearing it
Mu is the corrolary of = Just go outside and RIDE!!!

:rolleyes:

Haven't lost your sense of humor then Lucky :D