Gear inches, gain ratio, etc - does it matter how we gear it?
05-10-19, 09:52 AM
#26
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Yes there is. There IS SOMETHING very different about gearing ratio results - depending very much on the size of the front sprockets. Size matters!
Let's start by examining what happens to gear ratio results when using a 48 tooth sprocket. If this sprocket is used with a wide range 10-spd cassette - perhaps a 12-36 teeth range the resulting gear ratios would span a 4-to-1 ratio for high gear - all the way down to 1.333-to-1 ratio for low gear. If the front sprocket choice is 52 teeth - then the same cog selections result in 4.333 and 1.444-to-1.
If you can imagine that there are eight other gear ratio variations between these two extremes - AND - you review the ratio-variation between each individual cog's ratio - you will realize that ALL the gear ratios on the bigger sprocket are closer together than small sprocket. (often called gear "steps")
And the point I am trying to make about the selection of sprocket size and the resulting ratios is that depending on each rider's personal power-to-weight ratio - there IS an optimal gear ratio "step" range for each rider.
However, in modern times - with everyone choosing multi-sprocket chain sets - there are so many gear possibilities few riders notice or care. In practice - one of the few times I would expect this gear "theory" to be important would be a big guy riding a loaded touring bike in mountainous territory. (never needing double shifts under load)
Typically other aspects of bicycling power trains are more often noted - such as making sure that adequate gear ratio ranges keep a rider in the saddle no matter the load or grade. And just as importantly the optimal crank arm length and seat position for cycling terrain at hand.
Harrumph.
Let's start by examining what happens to gear ratio results when using a 48 tooth sprocket. If this sprocket is used with a wide range 10-spd cassette - perhaps a 12-36 teeth range the resulting gear ratios would span a 4-to-1 ratio for high gear - all the way down to 1.333-to-1 ratio for low gear. If the front sprocket choice is 52 teeth - then the same cog selections result in 4.333 and 1.444-to-1.
If you can imagine that there are eight other gear ratio variations between these two extremes - AND - you review the ratio-variation between each individual cog's ratio - you will realize that ALL the gear ratios on the bigger sprocket are closer together than small sprocket. (often called gear "steps")
And the point I am trying to make about the selection of sprocket size and the resulting ratios is that depending on each rider's personal power-to-weight ratio - there IS an optimal gear ratio "step" range for each rider.
However, in modern times - with everyone choosing multi-sprocket chain sets - there are so many gear possibilities few riders notice or care. In practice - one of the few times I would expect this gear "theory" to be important would be a big guy riding a loaded touring bike in mountainous territory. (never needing double shifts under load)
Typically other aspects of bicycling power trains are more often noted - such as making sure that adequate gear ratio ranges keep a rider in the saddle no matter the load or grade. And just as importantly the optimal crank arm length and seat position for cycling terrain at hand.
Harrumph.
Notice how every shift of the 52 gives a greater increase in gear inch than the 48 does with the same rear cogs. Especially important to know when custom tailoring ones system.
Oh, and by the way, that's some impressive mileage you have listed in your sig RC!
Last edited by AlmostTrick; 05-10-19 at 09:56 AM.
05-10-19, 11:15 AM
#27
Banned
Fwiw,
54 Gear inches is your 27" wheel turned by your crank in a 2:1 ratio ..
as if you had a Penny - Farthing bike with a 54 inch diameter wheel..
development is how far you get down the road, with 1 rotation of thar 54" wheel ..
as if you had a Penny - Farthing bike with a 54 inch diameter wheel..
development is how far you get down the road, with 1 rotation of thar 54" wheel ..
05-10-19, 11:35 AM
#28
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Right. It's just another way to measure the same thing.
05-10-19, 02:46 PM
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You bring up some very good points. Except you have the "gear steps" between a smaller/larger sprocket (chainring) reversed. The larger ring will provide farther, or greater gaps between each shift vs. the smaller ring.
Notice how every shift of the 52 gives a greater increase in gear inch than the 48 does with the same rear cogs. Especially important to know when custom tailoring ones system.
And my experience is that gearing for these gear ratio differences is actually more important than just having the widest possible range or the most perfectly spaced gearing that often requires double-lever shifting.
05-10-19, 10:00 PM
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Exactly! For any given cyclist, there is an optimal "average jump" or "step" that works best with their own cadence and power-to-load ratio.
And my experience is that gearing for these gear ratio differences is actually more important than just having the widest possible range or the most perfectly spaced gearing that often requires double-lever shifting.
And my experience is that gearing for these gear ratio differences is actually more important than just having the widest possible range or the most perfectly spaced gearing that often requires double-lever shifting.
Clicking through my well thought out gears, all on one shifter, has been quite satisfying. I've been quite happy with it so far... but sometimes it's still fun to tinker!
05-10-19, 10:27 PM
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Ben
05-10-19, 10:36 PM
#32
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Agreed. Everyones need's can be different.
05-13-19, 07:57 AM
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Like so many topics that are discussed online - bicycling equipment selections should be considered in the context of actual usage. My post was meant to identify the inherent limitations and benefits of theoretical gear ratio spacing.
Bicycle manufacturers make every effort to "average out" the various possible contexts or "everyday usage" scenarios when providing gearing for bicycles. I would suggest that cyclists that identify shortcomings of these "of the shelf" gearing configurations also have the knowledge as to why those gears were selected in the first place.
Truth be told - like "big gulps and big Macs" - most American consumers always believe more is better.
Bicycle manufacturers make every effort to "average out" the various possible contexts or "everyday usage" scenarios when providing gearing for bicycles. I would suggest that cyclists that identify shortcomings of these "of the shelf" gearing configurations also have the knowledge as to why those gears were selected in the first place.
Truth be told - like "big gulps and big Macs" - most American consumers always believe more is better.
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