Mod Bikes 24t-18t Compared To 18t-12t

[EranFuld]

Is there a dramatic difference or any difference at all regarding torque & weight balance between an 24T F - 18T R and 18T F - 12T R ?

I have a Monty 219 Magura /w White Industries ENO 18T on the rear and the original one piece Crank/24T Sprocket on front.

I'll be more than happy if you shared your knowledge/theories with me )

Thanks,

-E

[Maladie]

Is there a dramatic difference or any difference at all regarding torque & weight balance between an 24T F - 18T R and 18T F - 12T R ?

I have a Monty 219 Magura /w White Industries ENO 18T on the rear and the original one piece Crank/24T Sprocket on front.

I'll be more than happy if you shared your knowledge/theories with me )

Thanks,

-E

Umm, i'm pretty sure 24 - 18 and 18 - 12 would be exactly the same gear ratio ..

[Mark W]

It's not.

18 / 12 = 1.5, so for every full crank rotation you'd rotate your back wheel 1.5 times. To get the equivalent ratio to that with an 18t on the rear, you'd need 1.5 * 18 = 27.

Basically, it'll be easier to pedal than an 18/12 ratio would be if you run 24/18.

[Muel]

The biggest plus points if you ask me are weight and compactness, if you land on the chain it only has to flex up about 10mm before it hits the chain stay.

Not the best idea though, ruins your frame.

[Mark W]

The bonus of running 24:18 with the freewheel at the back is that you will get more effective engagement points, in that with a front freewheel setup with an Eno you'd get 72 clicks, whereas with it on the back per crank stroke you get 96.

[haderz]

The bonus of running 24:18 with the freewheel at the back is that you will get more effective engagement points, in that with a front freewheel setup with an Eno you'd get 72 clicks, whereas with it on the back per crank stroke you get 96.

out of interest. what is the logic behind this?

[durkie]

out of interest. what is the logic behind this?

if the freewheel is up front, rotating the cranks one full circle rotates the freewheel one full circle, or 72 engagement points.

for gear ratios greater than 1, rotating the cranks one full circle rotates the rear cog more than one full circle (think hardest gear ratio on a road bike: 52 up front, 13 in the back, or that rear wheel completes 4 revolutions for each one crank revolution).

so in the case of 24:18, your ratio is 1.333, so you get 72 * 1.333 = 96 total engagement points per crank revolution.

[EranFuld]

Umm, i'm pretty sure 24 - 18 and 18 - 12 would be exactly the same gear ratio ..

Thx

-E

It's not.

18 / 12 = 1.5, so for every full crank rotation you'd rotate your back wheel 1.5 times. To get the equivalent ratio to that with an 18t on the rear, you'd need 1.5 * 18 = 27.

Basically, it'll be easier to pedal than an 18/12 ratio would be if you run 24/18.

Makes sense....

-E

It's not.

18 / 12 = 1.5, so for every full crank rotation you'd rotate your back wheel 1.5 times. To get the equivalent ratio to that with an 18t on the rear, you'd need 1.5 * 18 = 27.

Basically, it'll be easier to pedal than an 18/12 ratio would be if you run 24/18.

Makes sense....

-E

The biggest plus points if you ask me are weight and compactness, if you land on the chain it only has to flex up about 10mm before it hits the chain stay.

Not the best idea though, ruins your frame.

Never thought about the clearance issue Hmmm interesting point.

Thx,

-E

if the freewheel is up front, rotating the cranks one full circle rotates the freewheel one full circle, or 72 engagement points.

for gear ratios greater than 1, rotating the cranks one full circle rotates the rear cog more than one full circle (think hardest gear ratio on a road bike: 52 up front, 13 in the back, or that rear wheel completes 4 revolutions for each one crank revolution).

so in the case of 24:18, your ratio is 1.333, so you get 72 * 1.333 = 96 total engagement points per crank revolution.

Now I've got the whole picture; thanks everyone )

-E