Why is equal gearing so important?
 

I was reading this morning about a type of gear system (Pinion) that offers equal gear spacing. This idea has been around for many years as a good thing. But my biological mechanics, do they really need equal gears? I don’t have much of an answer but my body tells me it’s not that linear. I mean when needed I can get out of the saddle and hump up a hill. And make it up just fine. Is this just me or anyone has any actual data. Thanks.

We don't need even spaced gears, we don't need any gears (well maybe at least one). We want the "right" gear most all the time though. Having gears in steps that mimic what our bodies like is the goal. Lot's of opinion and, likely research, suggests that 10 to 15% of ratio change between gears works well for many.

But you do live in the USA where it's your right to have any gearing spacings that you like. Andy

"Why is equal gearing so important?"

Its not for most folks. Andrew is correct in post #2 . a 10 - 15% range is fine. Low gears can even go to a 20% jump. Higher gears I'd try to keep closer to 10%. I often use the 21% drop between my 48 and 38 chainring climbing hills or approaching an intersection where I don't want to linger in traffic.

If you are on a professional racing team and that last 1- 2% efficiency means the difference between 2'nd and 6'th place, Or being kicked off the team, Then yes, Its important.

Evenness isn't all that important, but tightness can be. There are two ways in which evenness is useful...

One, erratic unevenness can mean that some of the gears are "wasted" being needlessly close together, leaving bigger gaps between other gears. The classic example of this is the conundrum of where to switch from 1-tooth jumps to 2-tooth jumps on a rear cluster; a 15-16-17 progression is tighter than anyone really cares about, but a 15-17 progression can be annoyingly wide sometimes. Throwing the 16-tooth cog between the 15 and the 17 means that gear steps elsewhere in the cluster will be wider (or the cluster will have less total range).
There's not really a perfect solution to this problem, it's a consequence of the mechanical realities of drivetrain types. In the case of derailleurs, it happens because the cogs need to have integer tooth counts.

Two, drivetrains that take advantage of interleaved ratios (like half-step) work best and are simplest when the rear cluster is as evenly-stepped as possible.

I would say that utterly equal spacing is unnecessary, but a big jump in the the middle of the most often used "cruising" gears can be annoying.

I'll almost always sacrifice range for a 16t cog. It's my magic cruising cog.

Me too.

I like my flat road gears to be relatively closely spaced. Hill gears I want to be able to feel the difference so I like wider spacing. Whatever Shimano calls that 7-speed gearing with 6 relatively closely spaced cogs and a bail out 7th - that's for me.

That gave me a bit of a chuckle this morning.
up north here too, we are allowed to use whatever cassette we like, and as a bonus, if we don’t know how to shift and fall off our bike and scrape our knee, when we go to emerg it’s free!
Win win ain’t it?

hey joe, look up Sheldon gear calculator, put in your bikes info and in the resulting chart will be the gear inches value of each gear, and beside each gear it will show the percentage jump between each gear.
et voila you’ll get a % number for what you have. Try diff cassettes and see the differences.

For going up hills, it doesn't matter too much. For road riding at higher speeds, most people have a desired cadence range. The next higher gear should fall into the range for efficiency.

For example, I like to be in the 93-105rpm range on a road ride. When I reach the 105rpm limit of my comfort zone and shift up to the next gear, I would like it to put me near my low limit of 93rpm. This allows me to keep producing a good amount of power without too much effort to get back into my most efficient cadence. If the next gear puts my cadence into the 80's, I have to put in a hard effort to get back up to my desired cadence and makes the ride less enjoyable.

Equally spaced gears are not important, but non-equally spaced gears means having some close together and some farther apart. The larger jumps are seen as a flaw in planetary gear systems, compared to derailleur systems that can claim, albeit generally through redundant gears and two shifters and derailleurs to keep moving, very small jumps between gears.

It's like the move between 7 speed (when I first entered the cycling industry in the late 80s) and 12 speed cassettes available now - for most 'performance' focussed riders, these extra gears are used to get smaller gaps between the gears and not higher or lower gears at the limits. A 2X12 (24 speed) with a standard double chainring2 (eg. 52-39) and road-racing cassette (~11-26) gives extremely small jumps between the gears if you know the best combinations. An 11 speed Shimano Alfine hub, for example, has bigger jumps, but you only need to futz with one shifter and it always goes up in one direction and down in the other.

Yuppers.

@OP. 2 current examples are the Rohloff 14speed IGH and the Alfine 11s hub. The Rohloff has a 526% range and keeps the steps even at about 13-14%....the Alfine hub is "only" a 408% range, and has similar stepping BUT for one jump that is a whopping 29%. The Alfine case is just odd, truly odd that Shimano would engineer something so consistently BUT for that one gear.

But-----------if you do have a gear system that steps up an equal amount why not?

If that 29% jump is in a range we seldom use, It shouldn't be a problem. If however it is in our cruising range it is a deal breaker. That range can probably be shifted some by using a different front and rear sprockets.

The Shimano MegaRange 7 speed cassette on my bike, And many other entry level bikes has a ridicules 41% jump to the next gear. 24 -34T. But with a triple chainring and the other 6 gears being properly spaced this drivetrain works very well. So it's not an issue. And for bikes with a single chainring, It might even be useful when climbing the big hill, Where a large change (25 - 30%) may actually be desirable.

Exactly. You adapt your gearing to your cadence, not your cadence to your gearing. Same thing with race cars. The gearing is close so that when you shift you stay in the RPM range for max torque and power.

It's impossible to have an equal percentage of change between sprockets, since the difference between a 12-13 and a 16-17, although both 1 tooth, are not the same percentage. At some point, like the 17-18, the percentage becomes so small that only a 17-19 makes sense. With the latest 12 speed cassettes, that's where campy moves up to a 2 tooth jump, then on to larger jumps for climbing. The new 11-34 12 speed cassette still has a 19-22 jump that's a tad too large.

It’s a pity that mechanics and anatomy has made us put the cassette at the rear.
That way,the smaller the sprocket becomes, the greater the impact of one tooth up/down becomes. It’s particularly annoying since when you get to that end, you’re probably moving at speed. And the faster you go, the more pronounced the effects of air drag becomes. If we had the reverse order - the big stack up front - it’d be far easier to make the increase smaller and smaller the faster you go.

(no, I don’t think this is hugely important. But the theory does make a bit of sense.)

If I were selling a planetary gear system, the sales pitch would be that equal spacing is paramount to efficient pedaling, and is the holy grail of gearing achievement. Honestly, it is for those that like to fuss about nothing. To each his own. Just ride.

You should input whatever gears you are interested in into some kind of gear calculator. You want to see the ratios or gear inches you will be getting with your combination of chainrings and cogs. Some setups have so many overlapping ratios that they are just a waste of gears, all you get are an extra gear or two when you downshift the front deraileur.

I appreciate all the thoughtful comments. It might matter that these days I mostly ride two different IGH hub bikes. One Biria 8 speed and the other a Linus 8 speed. Different Shimano hubs. You’ve made me think about what I like (or don’t) about the two. I think range is very important (of course) and after that the gearing steps near my usual gear is also very important. I will look up that gear calculator and think some more. Thanks.

I have a Nexus 8 on one bike. I dislike the 22.3% change from 5th to 6th. https://sheldonbrown.com/nexus8.shtml

Currently, my bike has sprockets of 42/20, which puts the top 4 gears in a usable range for me, but 5th is still a bit too low for my liking.

Currently, the gear inches in the top 4 gears are approximately 57.4", 70.2", 81.4", and 92.7".

I could change the sprocket teeth to 42/23 to close up the gap shifting to 70", which would give me gear inches of 49.9", 61.0", 70.8", 80.6". https://sheldonbrown.com/gear-calc.html

What I don't like about that is it would essentially turn my bike from a 4 speed into a 3 speed in usable gears. I'm a flatlander, so extra low gears go unused.

So, after many months, I've grown accustomed to the 5th gear to 6th gear gap and accept it for what it is. 22.3% is still a tighter gap than a traditional 3-speed hub of over 30%.

all this talk about 22% jumps being ok, Ive toured a lot over 30 years and when touring on a heavy bike, 20% jumps are a pain in the keester. Heck, on my commuter theres a 20% jump and its annoying.
Over the years, 9 spd touring cassettes, 11-32, 11-34 sort of thing, generally dont have bigger jumps than a one or two in the 16-17% range, and thats my limit of what I prefer to live with.
Heck, even 10 spd 11-36 have the max of a bit under 16%, which makes for a nice touring cassette.
* Yes, some of these cassettes have a slightly bigger jump between the 11 and 13 tooth, but frankly this doesnt count in being a factor, we are always going downhill going into a 11t, so not the same as more used % jumps we use all the time.

to the OP, you ride these IH bikes, but you would have to ride a derailleur bike with a closer spaced cassette to see how nice it is to ride, even touring.
Even commuting, a 20% jump just isnt necessary. even today on my commute the 20% jump I have between the 15t and 18t is niggling to me on a daily basis, depending on how much weight I have in my panniers.

But doesn't that depend on the tire/wheel size and the chainring size?

Yes! Which is why this opinion on gearing independent of the rest of the equipment is worthless. Andy

dsual's explanation probably explains why it's good to have gears that are properly spaced pretty well. They don't have to be equal, Just close - perhaps 10 - 12.5% increases to match our most efficient cadence range.

It's like a car or boat engine, There is a range where they are most efficient. Same with people. Some might find a cadence of 80 - 90 rpm is best for cruising, Recreational cyclists like myself perhaps 70 - 80 rpm.

Yes. It’s *my* magic cog. 53x16 on a 700c/25mm tire.

Yours might be different.