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I am wondering if people prefer equally spaced gears (such as 20% per gear change) or if (like on motorcycles), the lower gears are spread out more and the upper gears are "tighter" (more closely spaced as far as ratios). From my limited bicycle riding experience, other than the super low granny gear ratio, I like to have the lower gears spread out so the shifts are not instantaneous, and have the higher gears closer so for example, if you are chugging along at a good pace and encounter a slight headwind, you may not want to downshift and get about 20% more cadence. Perhaps 10% will suffice. Motorcycles generally have a spread of about 2.5 (street bikes) and some dual sport bikes are as wide as 3. For bicycles, since we have very limited input power (generally about a few hundred watts max), it seems we need many more gears and much closer spaced to harness that little bit of power.

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  • You can purchase (at least for some cog schemes) cog sets which are very "close" or cog sets which "spread" quite widely. For folks interested in racing on relatively flat courses a set with only one tooth difference between adjacent cogs has been used. The "standard" scheme assumes you want a wider range, and, in addition, would like it to be roughly logarithmicly arranged, so that the % change between adjacent cogs is roughly constant. Jan 21, 2016 at 13:42
  • Your title question doesn't match the body of the text, and the irrelevant aside is just bulk. What are you actually trying to do with your bike?
    – Móż
    Jan 21, 2016 at 22:24
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    My ideal jump is the negative log of my chain lube hydrogen ion concentration - I just refer to it as pH. It creates optimal torque if my protein : carbohydrate : fat ratio is between 10 and 12.
    – paparazzo
    Jan 21, 2016 at 22:50
  • Ok I did some testing today on my bike and made some observations. Equally spaced gears are not ideal since the shorter (lower) gears get shifted into and out of much quicker. For example, I can blast thru the lower gears in 1 second each but the higher gears take several seconds to muscle thru. Therefore it would make more sense to space out the lower gears starting at maybe 30% spread and gradually lessen to 10% for the higher gears. I will map this out in spreadsheet and see what I can come up with for perhaps a 7 speed and a 9 speed.
    – David
    Jan 21, 2016 at 23:17
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    Go ride up a two mile long hill with all your lower gears spaced at 25% and see how that works for you. Jan 25, 2016 at 17:47

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Ideal differences are generally thought of to be around 15%. Changes in excess of 20% make it difficult to select a proper gear for spinning based on varied conditions. Changes of less than 10% are so slight that they will almost unnoticeable to most unskilled riders and even some skilled riders.

You make an assumptions about the purpose of gearing on a bicycle that is incorrect. Gearing is present to provide the proper gear to maintain a near constant and comfortable for the rider cadence in a variety of changing conditions. They are not simply there to provide a shifting mechanism until the bike "gets up to speed". A combustion engine has a power range that is most efficient at a certain RPM, but there is no comfort level involved. It will produce any amount of power in it's range given the proper amount of gas. The human body does not work in the same manner. There is a very defined range that riders are comfortable producing power in. Generally producing power above that range causes drastic losses overall and can only be maintained for so long. You miss the point that lower gears also need to be closely spaced to maintain that output in conditions that greatly slow a bicycle (hills, wind, etc).

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    Ideally you would have a CVT type system like Nuvinci, but weight and complexity have resulted in such system being uncommon on bicycles. If you are working with derailleur gears using cogs, we've basically moved to the point where there is 1 tooth difference between adjacent cogs, with 2 teeth as the cogs get larger, and perhaps 3 teeth between the final 2 cogs. This is more a requirement to get the required range, and not because it is ideal in terms of efficiency. If they could get the same range with smaller steps, they would. Smaller gaps is always better in terms of efficiency.
    – Kibbee
    Jan 25, 2016 at 19:55
  • @Kibbee I forgot about those. I rode one once and was under impressed. Granted I didn't get a lot of time in on it, but it seemed closer to being a 3 speed with no indexing. I couldn't feel the differences between small shifts, so I ended up needing to move it in big jumps to get a noticeable difference. I am sure with enough use my brain would have converted, but I found myself missing indexing. Jan 25, 2016 at 22:51

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