Bicycle Mechanics - gear ratios...

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claude

11-24-00, 01:29 AM

Hi to all,

sorry if this question might seem banal to you people, but I just realised (about time I did ??) that newer bikes have got much smaller chainrings than my 10 year old MTB... want to make sure before I buy some bits...

Is the gear ratio measured as the difference between the number of teeth between the chain ring and cog ? Would a, for example 44-11 gear ratio feel exactly the same as a 48-15 ??

thanks for any feedback :)

claude

madsnake

11-25-00, 02:08 AM

The formula is:

number of teeth on chainring/number of teeth on cog x wheel diameter = gear inches. The result is the distance travelled for one pedal revolution.

Hence 44:11 = 104 gear inches.
48:15 = 83 gear inches.

52:13 would give you 104.

A good cycle mechanics book should give give you a table of gear inch equivalents.

claude

11-27-00, 12:34 AM

so, if I understood correctly, my older bike with a 48:13 ratio would actually be slower than a newer bike with 44:11 ratio, although the difference in teeth is actually more in the older bike....

claude