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« The significance of a decade ending in nine | Main | Christmas 1941 »
Monday
Dec312018

Gear Table

Bike stores used to give away gear tables as promotional or advertising material, it seems I hardly ever see them anymore. If I talk to a newbie bike rider about gears in inches they have no idea what I am talking about.

So in writing this I am not sure if I am dealing with a subject that most of my readership will already be aware of, or do those who don’t know even care? I’ll assume you do care and there may be some little snippet of information you will find interesting or useful.

Why do we talk of gears in “Inches?” For that you have to go all the way back to the Penny Farthing, or High Wheeler.

It was the diameter of the big wheel. A 60 inch or in other words 5 feet diameter wheel was a 60 inch gear.

This only became widely used when the chain driven bicycle came on the scene.

It became necessary to advertise these as having a similar 60 inch gearing, or higher or lower. A new buyer could compare that with what he was already used to.

The formula for calculating any gear is simple. Divide the diameter of the rear wheel by number of teeth on the rear sprocket.

Then multiply this by the number of teeth on your chainwheel. Assume the rear wheel is 27 inch for a road bike, this is not a precise measurement, but rather a comparison.

For example if you are using 50 chainring, with 18 tooth sprocket, you are in a 75.0 inch gear. (27 divide by 18, times 50 equals 75.) If you drop down to your 36 ring using a 13 tooth sprocket you are in a 74.8 inch gear. Close enough to be the same gear.

Back in the day we used to train on gears in the 60s or 70s, and race on gears in the 80s and 90s. Today on level terrain I ride around 69 or 70 inch. It allows me to pedal at around 72 to 75 rpm.

We used to spend hours studying gear tables, trying to find the ideal gear range. Possibly today’s bikes with 10, 11, and now even 12 sprockets on the rear hub, you are pretty much covered in any situation. Whereas, we only had 5 or 6 cogs on a freewheel, and it was necessary to choose each sprocket carefully depending on the terrain you planned to ride.

For a leisure rider today he has the luxury of more gears than he needs at the top or bottom of the range, and a rev counter to tell his cadence, so it really doesn’t matter what gear he is using. I think I have just answered my own question as to why the gear table is obsolete.

Hope you enjoyed the history aspect. May I take this opportunity to wish you all a Happy New Year? Be safe and stay healthy. A special thanks to my regular readers who have sent donations. These have helped tremendously to offset the cost of maintaining this blog and my Registry. Your kind help is much appreciated.

 

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Reader Comments (15)

I suppose with today's multiple closely-spaced gears, nobody has to worry about making any changes because every possible gear is there. I still think in terms of gear inches. But there is a metric equivalent, development in metres, which is the distance travelled for one pedal revolution, but more complicated to calculate. how many people use that? Similarly, the European way to measure tire pressure, in atmospheres instead of psi.

December 31, 2018 | Unregistered CommenterJohn B

Most riders I talk to now, have never heard of gears in inches, Now its, put it in the big cog in the back, and the middle chainring or some such.

December 31, 2018 | Unregistered CommenterAnthony J Crump

I have an old Millard 6sp freewheel on one of my bikes.
I bought it as a kit, the body and every cog from 13 though 24.
I sure spent time with gear tables trying to figure out the best spacing with the least duplication and overlap.
I have a newer bike with 11spd. I run a single chainring, all gears are unique and usable.
Gear tables don't matter any more when you have twice as may gears as you could ever use.

December 31, 2018 | Unregistered Commenteredstainless

Dave! Happy New Year and thanks for all those great posts in 2018!

December 31, 2018 | Unregistered CommenterMaynard Hershon

Happy New Year Dave. All sons raised on gear inches and how the terrain often dictates the wanted gear inch range. But most of our bikes still have only 6 rear sprockets. Our modern bikes have nine!

December 31, 2018 | Unregistered CommenterJack

Nowadays most people think that they need an 11 tooth cog to go fast....My mentor told me that when he was racing in the 50's, everyone used a 14-22 freewheel, that gave them a top end of 100 inch. When I started racing in the early 80's, I had a 13 as my "big" gear. With it, I was able to spin it up to 38mph in a sprint (with a long lead in and with a tailwind)…...Happy New Year.

December 31, 2018 | Unregistered CommenterBill K

Dave, thanks for all you posts in 2018 and keeping all the others available from earlier years. I enjoy them all and I usually lean something new. Today it was the origin of gear inches.
My highest sprocket count is 8 so I sill refer to gear inches to help identify the hole in the progression. I also used it to determine the gear inches needed for my SS/FG bike.
Happy New Year to you and yours.

January 2, 2019 | Unregistered CommenterSJX426

Happy New Year, Dave! Be safe and stay healthy and thank you for your posts!!!

January 2, 2019 | Unregistered CommenterMircea Andrei Ghinea

I run 11-28 8 speeds cassette on Freehub with 39 53 chainrings. Most of the time, I find myself shitting 2 cogs at a time as going just 1 cog is too little of a difference to bother with. On occasion I find benefit of closer spacing, but usually not. The thought of 11 or 12 speed cassettes strikeep me as rather silly.

Shoot, I showed up at Club ride last year on a 1963 Schwinn Tiger with 2 speed bendix hub. People were snickering at me. I was approache'd about how I might be out of place. I saidon't I figured I would ride with the D group. The D group all had carbon fantastics... I was warned that the pace would average 14 mph for 20 miles. I said, no problem. They reiterated that was average speed aND not top speed...

Geesh.... I told them I was a big boy and could find my way home by myself if needed and not to worry about me. I led the pack for the first 8 miles. I waited for them to catch up as I wasn't sure of the tur I ended up beating them all back home too oncertainly done. A few were complaining that it just wasn't right for me to be able to do that...

55 year old bike weighing 46 pounds with a 52 year old rider who logs 5,000 miles a year.

Now I grant you, I can ride with the British groupeople all day long on my Fuso with Suntour Superbe Pro components and descent new wheelset and freehub set up and the Tiger definitely slows me down. The point is, the new Hookah equipment won'the make you an ace. You have to get the engine modified...

January 2, 2019 | Unregistered CommenterRAYMOND FRECHETTE

The popular "modern" rear cog setup is no use to me. i have no need for an 11T or 12T cog- i rarely if ever go beyond the 15T cog. My bikes are set up with 6 or 7 speed freewheels and a 14-28 or 32 is all i need -if i need lower, i'll walk the damn hill! i really wonder how often anyone gets to the 11T in normal riding conditions?
i suppose my obsolete freewheels with proper care will long outlive me, but since no one other than a possible nutsy collector will ever want them, i guess they could be buried with me.

Happy New Year, Dave! Thanks for the gear table memories!

January 2, 2019 | Unregistered Commentermike w.

If you're old enough, you might remember long articles on various gearing schemes: Alpine, Half Step, Crossover, etc, back when you had a limited number of cogs in the back.

January 3, 2019 | Unregistered CommenterBrian

And back in those days we all spun 90/min as a normal cadence.
I recall practicing at 130-140, because that is what you had to do in order to go fast.
Today almost no one spins like that.

Makes me remember when I was young, strong, and living someplace very flat.
My top end was 56 x 14, with a bit of favorable breeze I could top it out.

January 4, 2019 | Unregistered Commenteredstainless

I have a business card from Alpha Bicycles with a gear table on it. Never used it. It’s circa 1983. We raced with a six-speed 13-21 freewheel for hilly road races, such as Willows or Boulevard, and for crits such as Manhattan or Hermosa Beach a 13-18 straight block was put on. The Campy Super Record cranks had 42 for the smallest ring, (never saw a 41), along with a 53 (some used 52) big ring.

Even though the Super Record rear derailleur had a 28-tooth capacity, I never used one. We rode up Palomar Mountain on the 13-21, and viewed 28-tooth as for tourists, I guess. But then maybe it just didn’t look right on a racing bike, like three rings on the crank, anathema in competition.

Anyway, I didn’t have a use for gear charts back then, and have no use for one today, as you concluded also.
But it does invoke nostalgia, because that is where we come from.

January 4, 2019 | Unregistered CommenterSteve

"...if i need lower, i'll walk the damn hill! i really wonder how often anyone gets to the 11T in normal riding conditions?"

I wonder, too. Today's gear sets are way too steep for most riders.

Thanks for the explanation, Dave. I remember gear inches, though always found it a bit baffling, and I had no idea that it traced back to the big-wheel penny farthing.

January 7, 2019 | Unregistered CommenterTBR

and with Excel nowadays we can make our own gear tables. Richard Ballantyne warned that one could become obsessed with gearing and I caught the bug. Being only human I cannot make use of the higher ranges and my big rings are 48T or less but I rode fixed for a few years and 52/21 (~67") brought much joy, downhill at 185 rpm on one occasion I thought I couldn't keep up but it levelled out and I am still here to tell the tale. I discovered that older front shifters could cope with granny gears on a double so 48/28 with a 7-speed freehub works really well. (I can't get on with development, I guess it's what you are used to). Imagining the big wheel of an ordinary is a useful metaphor and I can reach the pedals on wheels >48"!
Cheers, Dave

February 3, 2019 | Unregistered CommenterPeter

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