Driving force (Physics)

[91HBSi]

This is a kind of different thread, but I know there are a lot of smart guys on this forum.

Here is the scenario. There are two bicycles. Both have 20" diameter wheels and have the exact same components except for the drive train. Bike #1 has 175mm crank arms, a 33 tooth chainwheel (front sprocket), and an 11 tooth freewheel (rear sprocket). Bike #2 has the same 175mm arms, but has a 36 tooth chainwheel, and a 12 tooth freewheel. So both bikes have a gear ratio of 3:1. The question is, would the difference in the diameters of the sprockets cause a difference in the driving force or thrust?

There is a forumla but I can't find it.

[ec437]

Originally Posted by 91HBSi

This is a kind of different thread, but I know there are a lot of smart guys on this forum.

Here is the scenario. There are two bicycles. Both have 20" diameter wheels and have the exact same components except for the drive train. Bike #1 has 175mm crank arms, a 33 tooth chainwheel (front sprocket), and an 11 tooth freewheel (rear sprocket). Bike #2 has the same 175mm arms, but has a 36 tooth chainwheel, and a 12 tooth freewheel. So both bikes have a gear ratio of 3:1. The question is, would the difference in the diameters of the sprockets cause a difference in the driving force or thrust?

There is a forumla but I can't find it.

nope.

[91HBSi]

Could you elaborate a little? I'm pretty stupid

[v10_viper]

They're the same ratio, only thing truly affecting that would be weight, but that's so insignifcant it wouldn't make a difference.

[1stGenRocks]

Originally Posted by v10_viper

They're the same ratio, only thing truly affecting that would be weight, but that's so insignifcant it wouldn't make a difference.

are you sure. they are the same ratio front to back but the one with more teeth is a different ratio to the wheels then the one with less. i dunno what it works out to though.

[Steel]

Originally Posted by 1stGenRocks

are you sure. they are the same ratio front to back but the one with more teeth is a different ratio to the wheels then the one with less. i dunno what it works out to though.

no not really. 3:1 is 3:1 no matter how you cut it. The wheels don't know the difference, becasue there isnt one.

[AlmostStock]

http://sheldonbrown.com/gain.html

Lots of gear ratio/crank length math here. Sheldon knows all!

From the link:

What About Crank Length?

All of these systems share a common inadequacy: none of them takes crank length into account! The fact is that a mountain bike with a 46/16 has the same gear as a road bike with a 53/19 only if they have the same length cranks. If the mountain bike has 175's and the road bike 170's, the gear on the mountain bike is really about 3% lower!

[quteasabutton]

Originally Posted by 91HBSi

This is a kind of different thread, but I know there are a lot of smart guys on this forum.

Here is the scenario. There are two bicycles. Both have 20" diameter wheels and have the exact same components except for the drive train. Bike #1 has 175mm crank arms, a 33 tooth chainwheel (front sprocket), and an 11 tooth freewheel (rear sprocket). Bike #2 has the same 175mm arms, but has a 36 tooth chainwheel, and a 12 tooth freewheel. So both bikes have a gear ratio of 3:1. The question is, would the difference in the diameters of the sprockets cause a difference in the driving force or thrust?

There is a forumla but I can't find it.

there's some smart girls too. physics just isn't my thing or i'd prove it to you that there are smart girls here.

[fredjacksonsan]

Originally Posted by Steel

no not really. 3:1 is 3:1 no matter how you cut it. The wheels don't know the difference, becasue there isnt one.

[fredjacksonsan]

Originally Posted by quteasabutten

there's some smart girls too. physics just isn't my thing or i'd prove it to you that there are smart girls here.

I think you already have.

[quteasabutton]

Originally Posted by fredjacksonsan

I think you already have.

i hope ur not being sarcastic

[fredjacksonsan]

Originally Posted by quteasabutten

i hope ur not being sarcastic

Nope, you've held your own against a bunch of leg humpers and had intelligent commentary along the way. People aren't all smart the same way, so stop apologizing for it!