Track Cycling - Calculation of gear inches

What's the convention on this calculation of gear inches in the track field?

I note that a lot of people are quoting their gearing based on the 27" wheel, even though pretty much everyone rides on 700c. The difference may not be large, but it would appear that a good section of the track community are still living in the past, and out of reality with the equipments they use.

So what's the deal with this? Is the 27" wheel reference so deeply entrenched in track cycling? Or is there a move to face up with the reality?

The individual gear inches (say, 84 - 86 - 82) don't really mean anything significant. It's just an easy way of comparing one gear size relative to another. It matters not that the old 27" wheel size is still used as part of the equation.

There's probably a better way of measuring gearing such as Rollout or Gain Ratios but we are really more interested in relativity than actual gear ratios. Gear Inches are so engrained in cycling that all the old geezers (like me) understand them and young whipper snappers learn them.

There are so few absolutes in this world left to cling to, don't take away 50x15 = 90" :(

There are so few absolutes in this world left to cling to, don't take away 50x15 = 90" :(
Wasn't it Henry Rollins (Black Flag) that said "Friends may come and go but 500lbs will always be 500lbs."?

I guess you could modify that.

The individual gear inches (say, 84 - 86 - 82) don't really mean anything significant. It's just an easy way of comparing one gear size relative to another. It matters not that the old 27" wheel size is still used as part of the equation.

There's probably a better way of measuring gearing such as Rollout or Gain Ratios but we are really more interested in relativity than actual gear ratios. Gear Inches are so engrained in cycling that all the old geezers (like me) understand them and young whipper snappers learn them.
Yes, I appreciated the fact that this is all for comparative purposes. However, I am just amazed that there are so many who likes to stay with the old way, making accurate comparisons b/n track and other types of bikes difficult (yes, I appreciate the difference is only less than 3%).

Yes, I appreciated the fact that this is all for comparative purposes. However, I am just amazed that there are so many who likes to stay with the old way, making accurate comparisons b/n track and other types of bikes difficult (yes, I appreciate the difference is only less than 3%).
Why change if the present method (gear inches) is just for comparing gear ratios? What's not to understand about a 90" gear being bigger than an 88? We know that going from a 50/16 to a 50/15 will take us from 84" to 90" but if that jump is too big we need to go with 48/15 which will give us 86" or 52/16 for an 88. Most current trackies can pull that stuff out of their head.

Any other method will end up giving us what we already have - a gear comparison. What real benefit will change bring? I really don't want to compare gear sizes on my track bike vs a Moulton. If I ever do I'll get out my calculator.

Edit - I'll assume you're all switched over to the metric system from the silly, meaningless, ancient Imperial system. If so you will know relatively how tall I am at 1.7526 metres. That means nothing to most of us but my 5' 9" does.

Why change if the present method (gear inches) is just for comparing gear ratios? What's not to understand about a 90" gear being bigger than an 88? We know that going from a 50/16 to a 50/15 will take us from 84" to 90" but if that jump is too big we need to go with 48/15 which will give us 86" or 52/16 for an 88. Most current trackies can pull that stuff out of their head.

Any other method will end up giving us what we already have - a gear comparison. What real benefit will change bring? I really don't want to compare gear sizes on my track bike vs a Moulton. If I ever do I'll get out my calculator.
Why let reality and facts get in the way of convenience? Is that how trackies think?

Why let reality and facts get in the way of convenience? Is that how trackies think?

No, and why do you need to compair w road gears? Just know that 1 tooth in front= 2 and 1 tooth in back=6. How many decimal places do we need to take this to in order to make it reality?

No, and why do you need to compair w road gears? Just know that 1 tooth in front= 2 and 1 tooth in back=6. How many decimal places do we need to take this to in order to make it reality?
If that's the case, then why not just state the straight ratio b/n the number of front and rear teeth? Why bother adding the variable of wheel size in the equation? Given the preference is a constant of 27, why not use 10 or 20? It's even easier to calculate. Seems to me that people are trading their personal convenience for the primary reason on why gearing was defined that way.

There's probably a better way of measuring gearing such as Rollout or Gain Ratios but we are really more interested in relativity than actual gear ratios.

Junior gearing is still measured by rollout. Probably because 700c is a different rollout than 650c.

Dude, if you want to calculate gears so they are exact, go ahead, you'll be in your own little world doing your own thing. Like Mike said, it's for comparing relative sizes of gears. Yes we know that if you have a gear spread on a 700c and a 27 inch wheel, they are going to be different. The ratios are the same and that's all anyone cares about. Why reinvent a system that already works just fine and everyone gets.

Sure you can just state the ratios tooth x tooth. All you're doing is eliminating the "rollout" from the actual equation. People are still going to reference gears by rollout, so what's the point of dropping all the rollout numbers by 3%?

why not use a rifle to kill a fly instead of a fly swatter? they both work, one's already the accepted norm, but i bet the rifle would be a hell of a lot more accurate and lethal

I actually find the fly swatter to be a more effective tool than the rifle... when I'm killing flies.

Dude, if you want to calculate gears so they are exact, go ahead, you'll be in your own little world doing your own thing. Like Mike said, it's for comparing relative sizes of gears. Yes we know that if you have a gear spread on a 700c and a 27 inch wheel, they are going to be different. The ratios are the same and that's all anyone cares about. Why reinvent a system that already works just fine and everyone gets.

Okay so if my roommate wants to compare gearing with me, she should multiply her gear ratio by 27", even though her track bike has 24" wheels because, like Mike said, it's for comparing relative sizes of gears.

You see my point? Gear inches do more than just compare gear ratios, they compare wheel/tire sizes as well. It's slightly more abstract than development/roll-out but not much - multiply your gear inches by pi and you get your development/roll-out.

The difference between 700C wheels with skinny tires (20-23C) and 27" wheels is pretty small so for simple comparisons it's fine, but at that point, why bother multiplying by 27 in the first place? Just compare the gear ratios (i.e. - 3 is a smaller gearing than 3.2).

Sogood, so what's your suggestion of how we should state our gear sizes? And how do you propose to get the whole of the English speaking cycling world to change to your method?

I don't understand the "hands" measurement in horse circles. "15 hands" means nothing to me but I'm sure 5' would, compared to a 5' 5" horse. But if I got into horses I'll bet the "hands" measurement would make sense in time.

Yes I'm sure 48 div by 16 (which equals 3) would make sense in time and just as much sense as 48 div by 16 x 27 (which equals 81) but Gear Inches has been around for a little while (like a hundred years) and almost everyone who's really into cycling understands it.

Sorry if you don't agree with the majority of the English speaking cycling world. We're happy with the present system but then I'm happy with Imperial measurement even though I live in Canada and some stuff is measured in Metric. Try going to the lumberyard and asking for a ten foot 2x4 in metric. Hell a 2x4 doesn't even measure 2x4 but we ALL know how relative that is to a 2x6 that doesn't measure 2x6 either.

If that's the case, then why not just state the straight ratio b/n the number of front and rear teeth? Why bother adding the variable of wheel size in the equation? Given the preference is a constant of 27, why not use 10 or 20? It's even easier to calculate. Seems to me that people are trading their personal convenience for the primary reason on why gearing was defined that way.

"Jargon is terminology that relates to a specific activity, profession or group. Much like slang it develops as a kind of shorthand, to express ideas that are frequently discussed between members of a group."

If my coach or team mate asks me what im riding and I reply 88; He knows what that means, knows the strategic implications that has on how I should ride, ect. A lot of unspoken communication in that simple exchange.

As an engineer I agree with your accuracy argument, as a racer I dont really feel like changing the world on this one.

"Jargon is terminology that relates to a specific activity, profession or group. Much like slang it develops as a kind of shorthand, to express ideas that are frequently discussed between members of a group."

If my coach or team mate asks me what im riding and I reply 88; He knows what that means, knows the strategic implications that has on how I should ride, ect. A lot of unspoken communication in that simple exchange.

As an engineer I agree with your accuracy argument, as a racer I dont really feel like changing the world on this one.
Best answer yet. Thanks.

As an engineer I agree with your accuracy argument, as a racer I dont really feel like changing the world on this one.

The only time it would make a difference is that you could be specific about the difference between race tires and training tires. Still it's usually not more then a 1/2" so just saying a "little bit" is probably adequate.

Sogood, so what's your suggestion of how we should state our gear sizes? And how do you propose to get the whole of the English speaking cycling world to change to your method?
I don't propose my own system but just surprised that people are clinging to a spec (27") that has long disappeared. If years ago the Brits had the 700c wheels, the person who came up with that gearing calculation would have used the 700c spec to fully realise the purpose of the gearing calculation (relationship of three variables). I think that guy would be turning in his grave given what people are doing to his mathematical invention.

As much as 3% is a tiny difference b/n the 27" and 700c spec. But in these days of high tech sports science where winning and losing is separated my mere 1/100th of a second, how can people be so blasé with this number? Do the top tier sports scientists also ignore the 27" vs 700c spec in their calculations for the world cup or Olympics?

As an engineer I agree with your accuracy argument, as a racer I dont really feel like changing the world on this one.
Thank you. So it is an attitude issue with track riders knowingly staying inaccurate. At the same time, I wonder how many track riders actually know that they are quoting inaccurate numbers?

Sogood, so what's your suggestion of how we should state our gear sizes? And how do you propose to get the whole of the English speaking cycling world to change to your method?

I don't understand the "hands" measurement in horse circles. "15 hands" means nothing to me but I'm sure 5' would, compared to a 5' 5" horse. But if I got into horses I'll bet the "hands" measurement would make sense in time.

Yes I'm sure 48 div by 16 (which equals 3) would make sense in time and just as much sense as 48 div by 16 x 27 (which equals 81) but Gear Inches has been around for a little while (like a hundred years) and almost everyone who's really into cycling understands it.

Sorry if you don't agree with the majority of the English speaking cycling world. We're happy with the present system but then I'm happy with Imperial measurement even though I live in Canada and some stuff is measured in Metric. Try going to the lumberyard and asking for a ten foot 2x4 in metric. Hell a 2x4 doesn't even measure 2x4 but we ALL know how relative that is to a 2x6 that doesn't measure 2x6 either.

Mike, you seem to be completely missing the point as to why people use gear inches over gear ratios. Gear inches (and development meters) take into account your wheel/tire size which allows you to compare how "hard" or "easy" a gear/wheel combo is to another. If a mountain biker, a roadie, a BMXer and a guy on a folding bike wanted to compare their gearing, using gear inches (or development meters) would be a far superior method to just gear ratios, because riding a 48x16 with 20" tires is a lot easier than riding a 48x16 with 700x23C tires.

Sogood isn't suggesting we stop using gear inches but that people use the correct tire measurement when doing the calculations. 27" maybe be "close enough" when comparing 700C tires but it's not accurate and makes comparisons with other wheel sizes difficult.

So for the record, a 700C wheel is 622mm in diameter, or 24.5". Add on a 23C tire (which is 23mm thick, adding a total of 46mm to the diameter of the wheel) and you get a diameter of 668mm or 26.3".

My track gearing is 48x15 so that would give me the following gear inches:
27" tire: 86.4"
700x23C tire: 84.2"
700x20C tire: 83.4"

So if I'm using a 20C tire and do the calculates with 27", I'm off by 3 gear inches, which is significant.

Thank you. So it is an attitude issue with track riders knowingly staying inaccurate. At the same time, I wonder how many track riders actually know that they are quoting inaccurate numbers?

Without a doubt, its jargon more than purely technical info. When I say im riding a 90 or :eek: 92 that's an expression that my intention is to push a high pace as much as to define a specific and accurate gear ratio.

If im gonna be really accurate dont I need to also factor in Tire Pressure, rider weight, weight distribution? Really doesn't seem worth all the work so I can say im riding a 91.2879 or whatever.

Do the top tier sports scientists also ignore the 27" vs 700c spec in their calculations for the world cup or Olympics?

Probably (at least the elite coaches I know do)-- they pick the right gear for the situation, but they call it the same thing as everybody else. That is, if they'll even tell you...

The calculation is chainring teeth divided by cog teeth, multiplied by a constant. Whatever you want to make the constant, it still is a reliable ratio to use for comparison of gearing. It happens to work into a number that is big enough so you aren't working out into two decimal places plus it's something everyone has worked with for years. If you want to go around saying your gear ratio is 2.328, fine. Even on the track where people are changing gears repeatedly in an evening, and a couple inches worth of gear is meaningful, people just use the traditional measure. Frankly, there aren't many road wheels that aren't 700C any more and nobody's going to get pedantic about the measurement. You have to multiply the gear (in inches) by pi anyway to get rollout, which means you could argue that no one's expressed it right since time began anyway. Time to move on. Next thread?

The calculation is chainring teeth divided by cog teeth, multiplied by a constant. Whatever you want to make the constant, it still is a reliable ratio to use for comparison of gearing. It happens to work into a number that is big enough so you aren't working out into two decimal places plus it's something everyone has worked with for years. If you want to go around saying your gear ratio is 2.328, fine. Even on the track where people are changing gears repeatedly in an evening, and a couple inches worth of gear is meaningful, people just use the traditional measure. Frankly, there aren't many road wheels that aren't 700C any more and nobody's going to get pedantic about the measurement. You have to multiply the gear (in inches) by pi anyway to get rollout, which means you could argue that no one's expressed it right since time began anyway. Time to move on. Next thread?

Historically gear inches were used when people were still riding penny-farthings. The number of gear inches was simply the diameter of the big wheel. This was useful when comparing two penny-farthings and gave just as much information as roll-out (though again, slightly more abstract). When the safety bicycle was invented they then had to multiply the wheel diameter by the gear ratio, which is what is used today.

Multiplying by 27" isn't about multiplying by a constant (if that were the case, everyone would use 10 or 100). It's about expressing a number that is accurate independent of the size of the chainring, cog and tire. It's not about how many decimals you need to express, it's about having a figure that can be compared across multiple bike setups.

Even if you are using 700C road wheels, different tire sizes are going to give you a different number of gear inches. A bike geared at 51x15 with a 20C tire will have a gearing of 88.6". Throw a 30C tire on and it's now 91.3". This isn't being pedantic either - I use 23C tires on my commuter bike but when it snows I put 32C tires on, which increases my gearing by 2.1".

Take a look at any gear inch calculator. It will ask you for your wheel size and your tire size. This is because it does it correctly. You can bet that on the professional level they are using the correct method.

I'm sorry if you've been doing it wrong your entire life but that's no reason to spread misinformation.

Now it is time to move on. Next thread.

EDIT: Basically what I'm trying to say is that while multiplying your gear ratio by 27" might be a decent approximation for a 700C wheel it is not the proper method for calculating gear inches. It's an approximation and it doesn't work for other wheel/tire sizes.

The correct way is by multiplying by the diameter of the wheel. Multiplying by 27" is like multiplying by 3 instead of pi to determine the roll out. A decent approximation, but when you try to claim that multiplying by 3 is the appropriate method you just sound foolish.

Take a look at any gear inch calculator. It will ask you for your wheel size and your tire size. This is because it does it correctly. You can bet that on the professional level they are using the correct method.


I wouldn't be so sure. Everyone I know uses the method that they've known since their first coach told them to put an 81 on.

You seem to misunderstand what gear inches are used for at the track. Gear inches are used so that you can relate what gear you're in to someone else in an easily remembered number. Since everyone has a 19-23mm tires you're off by a half inch at most which as far as talking to others isn't really meaningful. However since EVERYONE understands gear inches to be based on a 27" wheel saying anything else is going to convey incorrect information. The other use is for you to know what various gears feel like to you. It's far more important that you remember what the number is than it be an actual calculation of gear inches. And that means that one set of numbers is better than a different one for every mm of tire size so why not just use 27".


for example:
Everyone get in an 81 for this warmup.
Guy on motor:what gear are you in
You(breathlessly):84.
hmmm last time I was here I was spinning out in an 88.6 but fine at home. Now I'm spinning out in an 88.6 at home I should gear up even more here.

As I said the only advantage would be to have an exact relation between race tires and training tires rather then the normal "it's a little bit lower."

...You seem to misunderstand what gear inches are used for at the track. Gear inches are used so that you can relate what gear you're in to someone else in an easily remembered number. Since everyone has a 19-23mm tires you're off by a half inch at most which as far as talking to others isn't really meaningful. However since EVERYONE understands gear inches to be based on a 27" wheel saying anything else is going to convey incorrect information. The other use is for you to know what various gears feel like to you. It's far more important that you remember what the number is than it be an actual calculation of gear inches. And that means that one set of numbers is better than a different one for every mm of tire size so why not just use 27".

...

Yes!

Sorry but I'm going to have to disagree. People who are using 27" because "that's the way it's always been done" are doing it incorrectly.

At the track using 27" for an approximation is fine. It'll give you a good idea of how easy/hard a gear is.

For many other applications it's not okay. For example, UCI roller races have a maximum gearing of 96.37". If you use 27" in your calculations and find an optimal gearing, it will most likely be sub-obtimal. True the UCI rulebook also specifies development meters (7.69m) so it's less ambiguous, but you see my point (I hope).

All I'm saying is that the formula for gear inches is: gear ratio * tire diameter. The fact that gear ratio * 27" will give you completely wrong figures for any tires other than 27" or 700C tires should give you a hint as to why.

Yes, at the track 27" will be close enough for whatever you're doing and I know I've used 27" to estimate gear inches before, but I've also routinely used 3 instead of pi to make quick calculations and I don't claim that pi is exactly three.

In conclusion, claiming that using 27" is the correct way of calculating gear inches is exactly the same as saying pi equals 3.*

*slight exaggeration

To every one who insists that gear inches are calculated by multiplying by 27" (and that's the correct way to do it) answer this:

My roommate uses 24" wheels on her track bike. If someone tells her she should use an 81" gear to warm up, should she use a 54x16 gear ratio or a 48x16 gear ratio?

Sorry but I'm going to have to disagree. People who are using 27" because "that's the way it's always been done" are doing it incorrectly.

At the track using 27" for an approximation is fine. It'll give you a good idea of how easy/hard a gear is.

For many other applications it's not okay. For example, UCI roller races have a maximum gearing of 96.37". If you use 27" in your calculations and find an optimal gearing, it will most likely be sub-obtimal. True the UCI rulebook also specifies development meters (7.69m) so it's less ambiguous, but you see my point (I hope).

All I'm saying is that the formula for gear inches is: gear ratio * tire diameter. The fact that gear ratio * 27" will give you completely wrong figures for any tires other than 27" or 700C tires should give you a hint as to why.

Yes, at the track 27" will be close enough for whatever you're doing and I know I've used 27" to estimate gear inches before, but I've also routinely used 3 instead of pi to make quick calculations and I don't claim that pi is exactly three.

In conclusion, claiming that using 27" is the correct way of calculating gear inches is exactly the same as saying pi equals 3.*

*slight exaggeration

Noone is saying it gives you an accurate measure of actual gear inches. They are saying that having such a number is worthless most of the time. Since everyone is off by more or less the same amount it lets you convey information to other people. Since you are always off by more or less the same amount it lets you keep track of information using a measure you're going to have to know to talk to other riders, coaches, pacers, officials etc. Noone is calculating gear inches in their head they know them or are learning them from a chart or by being told repeatedly. The measure gains more usefulness by being easily remembered than it would by actually measuring what it appears on the surface. More importantly though it's what everyone uses and to start using something else will result in a failure of communication.

You're too hung up on what gear inches actually are an not concerned enough with the function they serve on the track

To every one who insists that gear inches are calculated by multiplying by 27" (and that's the correct way to do it) answer this:

My roommate uses 24" wheels on her track bike. If someone tells her she should use an 81" gear to warm up, should she use a 54x16 gear ratio or a 48x16 gear ratio?

unusual case. You failure to understand gear inches has led you to a mistake here anyway.

She should be using a 57x16(unlikely) or a 50x14 because she's not trying to match a real 81.0 but rather a 78.4

Thank you. So it is an attitude issue with track riders knowingly staying inaccurate. At the same time, I wonder how many track riders actually know that they are quoting inaccurate numbers?

Maybe quite a few. When I took my beginner's lessons from a San Diego track coach, he explained gear inches to me by noting that the 27" system was antiquated, but still what everyone used because it was known and customary and therefore the best way to communicate gearing information.

Then I was in a bike shop in Oakland asking about some track chainrings I wanted and had a hard time because I was talking 27" and the shop owner was talking 700cc. That was the first time that had happened to me. He was working off the gearing chart that comes with the EAI Kierin bag (that has gear inches listed for 700cc). I homemade one for myself based on 27" so that I could talk to the folks at my track, who seem to all work with that.

At the end, I have to agree with the folks who say that, although "inaccurate," the 27" convention is most useful for communicating with those I ride with. And since we all use gear inches primarily as a shorthand to assess relative effort, and nobody really cares how many actual inches on the pavement the bike moves for one revolution of the pedals, what's the big deal with being consistently and usefully inaccurate?

(Obviously, this convention may not help the road-fixie rider, or the BMX racer, or even the 650cc wheel user. But since we are posting in the track forum . . . how many riders at your track are using anything other than 700cc wheels with a 19-23 tire? In which case, inaccurate is nonetheless consistent and useful.

Just so we get the OP's proposal, as I understand it:

1. Actual tire diameter must be used, measurement accuracy to be defined (although reporting Gear Inches within 0.1" would require measurement within 0.0031" applying the 10:1 rule).
2. Number is based on unloaded bike (no rider).
3. Gear Inches are recorded and quoted to the nearest 0.1" (assuming im honest anyway ;) )?

Is that about right? :)

Take a look at any gear inch calculator. It will ask you for your wheel size and your tire size. This is because it does it correctly. You can bet that on the professional level they are using the correct method.

I'm sorry if you've been doing it wrong your entire life but that's no reason to spread misinformation.

Now it is time to move on. Next thread.

Actually, if you actually go to any track, you'll find everyone simply talking about an 81" gear or even a 77.9" gear or a 92.6" gear. They get down to the decimals but they still talk about it in the standard (27") calculation. No one multiplies it in their mind by pi to get rollout (unless it's a junior getting their bike qualified before a race) -- it's just a way of communicating the gear you're in to compare with what someone else might be riding, or to communicate to a mechanic what gears you want. Until you actually get down to speed generated, people who actually race don't care about the intermediate steps. I might be doing jumps on training wheels with big Conti Steher tires while the teammate next to me is riding 19 mm Vittoria Evo Pistas. I'll have a slightly higher true gear, but I can assure you that no one bothers to differentiate. So I'd suggest that rather than getting ugly you simply look at what elite track riders actually do and understand that the status quo is satisfactory for them. If someone wants to get their tail twisted over alternative ways to calculate gearing, fine. But then start figuring in crankarm length and wattage and while you're at it, just go straight for a speed and cadence calculation rather than anything short of that. I do actually do this for most of my living, and so do most of the people around me, and you might actually ask a "professional" rather than presuming that a "professional" will agree with you. Expertise is a lot more useful than someone simply talking about it.

Chat Reel: Marty Nothstein
Cyclist on track for Sydney gold
Posted: Thursday June 08, 2000 07:10 PM

From Jeff in Seattle, Wash.: Do you use the same gearing in the keirin as you do in the match sprints? How many gear inches do you use in the match sprints? The keirin? Do you prefer keirin racing or match sprints?

Marty Nothstein: There's no preference in either race - they're both sprint style. I like both. As far as the gears go, I'll normally ride a bigger gear in the keiran. For example, I'll normally ride 50 x 14 or 51 x 14. Which translates to a 96 inch gear. For the sprints, I ride either a 48 x 14 or 49 x 14. Which is between a 92 and 94 inch gear.

Noone is saying it gives you an accurate measure of actual gear inches. They are saying that having such a number is worthless most of the time.

You're too hung up on what gear inches actually are an not concerned enough with the function they serve on the track

No, there are people here who are saying that the correct formula for calculating gear inches is:

27" * chainring / cog

Ignore the fact that we are on a track forum. Ignore that we are talking about comparisons between bikes that have similar sized wheels. I'm sure you'll agree with me that that formula is not correct. What it gives you is a decent approximation of gear inches for a 700C tire. That is all I've been saying. All I've been saying is that track racers are using an approximation for gear inches. I'm not even saying that you shouldn't do it that way. I'm just saying that it's not an accurate measurement of actual gear inches (like you just said) whereas there are people here who are claiming that gear inches mean absolutely nothing, it's just a constant multiplied by the gear ratio, and that constant happens to be 27 (which I'm sure you'll agree is totally false).

Should I make some snide comment about reading comprehension?

So is this where we are . . .?


What's the convention on this calculation of gear inches in the track field? Most track riders speak with reference to a 27"-based calculation.


I note that a lot of people are quoting their gearing based on the 27" wheel, even though pretty much everyone rides on 700c. That's right.


The difference may not be large, but it would appear that a good section of the track community are still living in the past, and out of reality with the equipments they use.? Yes, but it serves their purpose well.


So what's the deal with this? Is the 27" wheel reference so deeply entrenched in track cycling? It appears so.


Or is there a move to face up with the reality? No.

Dutret and others:

I want to make it abundantly clear that I'm not trying to say that track racers should not use 27" or that using exact numbers is better when it comes to track racing. If you said to me "The correct way to calculate gear inches on the track is to use 27 inches" I might even agree with you.

However there was a lot of misinformation in this thread, for example 11.4 posted this: "The calculation is chainring teeth divided by cog teeth, multiplied by a constant. Whatever you want to make the constant, it still is a reliable ratio to use for comparison of gearing."

I'm sure almost everyone here except 11.4 will agree that that statement is 100% false.

Basically what I'm trying to get across is that there are two things - gear inches (computed by tire diameter) and the track gear inch approximation (calculated using 27") and that THEY ARE NOT THE SAME.

Dutret and others:

I want to make it abundantly clear that I'm not trying to say that track racers should not use 27" or that using exact numbers is better when it comes to track racing. If you said to me "The correct way to calculate gear inches on the track is to use 27 inches" I might even agree with you.

However there was a lot of misinformation in this thread, for example 11.4 posted this: "The calculation is chainring teeth divided by cog teeth, multiplied by a constant. Whatever you want to make the constant, it still is a reliable ratio to use for comparison of gearing."

I'm sure almost everyone here except 11.4 will agree that that statement is 100% false.

Basically what I'm trying to get across is that there are two things - gear inches (computed by tire diameter) and the track gear inch approximation (calculated using 27") and that THEY ARE NOT THE SAME.

unless you tire is exactly 27". I think everyone here(except maybe mike t) understands that and what's going on in this thread. I read 11.4s quote to mean that there is a constant for any bike.

The real question here should be why does the eai keirin tote come with a chart that's not based on 27".

Dutret and others:

I want to make it abundantly clear that I'm not trying to say that track racers should not use 27" or that using exact numbers is better when it comes to track racing.

Yea, there are really 2 different discussions here, yours regarding accuracy in calculating Gear Inches which really cant be argued with. And the OP's question regarding use of Gear Inches in the Track community
The difference may not be large, but it would appear that a good section of the track community are still living in the past, and out of reality with the equipments they use.?

First I want to say I stand corrected when I said that professionals use tire diameter. Apparently I was wrong. I also assumed that many people did use tire diameter since I do, as do many of the people I know. However a lot of the people I race with are software engineers (I'm one myself), mathematicians (well math teachers anyway) or architects so we would tend to use the accurate figures.


unusual case. You failure to understand gear inches has led you to a mistake here anyway.

She should be using a 57x16(unlikely) or a 50x14 because she's not trying to match a real 81.0 but rather a 78.4

True, assuming everyone else is racing on 20C tires then she should use a gear that is close to 78.4" (I was over simplifying slightly). This is the reason why I think people should use accurate numbers as the burden is now on her to correct the figures when calculating her gear ratio.

And yeah, the gearing should be 50x14 since 24" wheels aren't actually 24" (much like 700C aren't 27"). The numbers I used were for the sake of argument, although I guess I should have been more accurate since I've been arguing about accuracy/appoximation this whole time.

First I want to say I stand corrected when I said that professionals use tire diameter. Apparently I was wrong. I also assumed that many people did use tire diameter since I do, as do many of the people I know. However a lot of the people I race with are software engineers (I'm one myself), mathematicians (well math teachers anyway) or architects so we would tend to use the accurate figures.



True, assuming everyone else is racing on 20C tires then she should use a gear that is close to 78.4" (I was over simplifying slightly). This is the reason why I think people should use accurate numbers as the burden is now on her to correct the figures when calculating her gear ratio.


I think the split comes not between technical and non-technical people but rather between those that learned gear inch numbers on the track or people who were using the measure long before they were ever exposed to the inaccuracy of the track system.

It's not much a burden, instead of learning the set of numbers the rest of do she just has to learn her own. The same would be the case if we used real gear inches. The only important thing is that she understands that the gear inches aren't actual gear inches and takes that into account when she makes a chart.

The real question here should be why does the eai keirin tote come with a chart that's not based on 27".

At least the EAI chart is explicit as to its measurement basis:

I think the split comes not between technical and non-technical people but rather between those that learned gear inch numbers on the track or people who were using the measure long before they were ever exposed to the inaccuracy of the track system.

Do the road bikers you ride with talk of gear inches? I'd be interested if "yes," and in what context.

Guys I ride with, of all experiences and skills, may note that they are riding a 53/39 versus a compact, or a 25 or 27 cog for a hilly day, but I've never had a discussion with them about road bike gear inches.

Although I long ago found Sheldon Brown's untra-precise online calculator, and I've even used it a few times to generally compare the gearing across my couple of bikes and wheelsets, I never really learned to talk or care about gear inches until I rode at the track, at which point I was quickly indoctinrated into the 27" school.

Do ProTour riders pay attention to gear inches? I would think that they do.

However a lot of the people I race with are software engineers (I'm one myself), mathematicians (well math teachers anyway) or architects so we would tend to use the accurate figures.

I'm an experimental physicist, and I use 27". It makes it easier to talk to everyone else when you're using the same language. I can see what wheels and tires they're using and adjust if I feel I need to.

I'm an experimental physicist, and I use 27". It makes it easier to talk to everyone else when you're using the same language. I can see what wheels and tires they're using and adjust if I feel I need to.

Concur. And Yoshi, your derogatory and inappropriate comments aside, I'm a physical chemist and x-ray crystallographer. I actually do understand numbers. And I've also raced track for 25 years at national and international levels. Bitingduck races actively at ADT in Los Angeles. Again, if one talks to those who actually race, this is a non-issue (and this is a track forum).

Do the road bikers you ride with talk of gear inches? I'd be interested if "yes," and in what context.

Guys I ride with, of all experiences and skills, may note that they are riding a 53/39 versus a compact, or a 25 or 27 cog for a hilly day, but I've never had a discussion with them about road bike gear inches.

Although I long ago found Sheldon Brown's untra-precise online calculator, and I've even used it a few times to generally compare the gearing across my couple of bikes and wheelsets, I never really learned to talk or care about gear inches until I rode at the track, at which point I was quickly indoctinrated into the 27" school.

Do ProTour riders pay attention to gear inches? I would think that they do.

I was thinking more along the lines of:

than

Concur. And Yoshi, your derogatory and inappropriate comments aside, I'm a physical chemist and x-ray crystallographer. I actually do understand numbers. And I've also raced track for 25 years at national and international levels. Bitingduck races actively at ADT in Los Angeles. Again, if one talks to those who actually race, this is a non-issue (and this is a track forum).

Sorry, I didn't mean to sound derogatory - people were arguing with me over what amounted to semantics and I was trying to make very clear what I was trying to get across - that there was some misinformation in this thread. I can see now that that misinformation was a result of over-simplification not ignorance.