Author Topic: Does anyone know what gravel is?  (Read 8256 times)

Re: Does anyone know what gravel is?
« Reply #100 on: August 27, 2018, 10:14:59 am »
I'd agree that ERTO tyre designations are the One True Way, but, despite being fully metricated in my daily life (pints and miles perhaps excepted), gear inches do make sense; as mzjo points out, you end up with a useful range of between about 20 and 100, and quoting to the nearest exact inch gives a useful amount of precision. Yes, if you trace the origin back it's easy to be all 'hur dur penny farthing', but plenty of fields have weird customary units that work for their purposes; think wire gauges, gem carats, or typographic points. It's not like development, despite the apparent rationality, is actually all that useful in and of itself; to go from cadence to speed (whether m/s or km/h) still involves a conversion factor, meaning it's not any better from a mental arithmetic POV.

quixoticgeek

  • Mostly Harmless
Re: Does anyone know what gravel is?
« Reply #101 on: August 27, 2018, 12:26:53 pm »
I'd agree that ERTO tyre designations are the One True Way, but, despite being fully metricated in my daily life (pints and miles perhaps excepted), gear inches do make sense; as mzjo points out, you end up with a useful range of between about 20 and 100, and quoting to the nearest exact inch gives a useful amount of precision. Yes, if you trace the origin back it's easy to be all 'hur dur penny farthing', but plenty of fields have weird customary units that work for their purposes; think wire gauges, gem carats, or typographic points. It's not like development, despite the apparent rationality, is actually all that useful in and of itself; to go from cadence to speed (whether m/s or km/h) still involves a conversion factor, meaning it's not any better from a mental arithmetic POV.

Except for the simple fact that outside the UK and the US, your average person doesn't know what an inch is. I described something to a Dutch work colleague the other day as 6 inches. He said "what's an inch?"

It's easy when you have been brought up with the abominable combination of units in the UK, to think everyone knows that an inch is 25.4mm, but the reality is, that noone does. For many who use gear inches for their gearing, it's purely because they are familiar with it. I wasn't bought up on it, and have to sit down and do maths to realise that a 28" gear is the same as my 2.1m gear (34/34 * 28).

Thing is if I know that my gear is is 5m of development, I can than easily work out that 5m x 90 rpm, gives me 450m per minute, x 60, gives me 27000m/h or 27kph. You can also do something same thing in reverse. "I want my top gear to allow me to do 50kph at 90rpm." 50000 / 60 / 90 = 9.26. divide by pi, then divide the wheel diameter (I'm using 0.7 just for simple maths in this example).  This gives you the ratio between your front and rear sprockets. If I want to decide on which chain ring to use, multiply by that, so if my cassette is fixed at 11, so what chain ring do I need.

50000/60/90/pi/0.7 * 11 = 46.3

46t chain ring. And if I have my 50t chain ring and want to decide on my cassette size, I divide the chain ring instead

50 / (50000/60/90/pi/0.7) = 11.875 so a 12 tooth realistically.

At risk of tying this to a discussion elsewhere on the forum anyone born after the mid seventies should have been brought up in an education system that is fully metric, they should have been taught m, cm, l, g, etc... and unless they picked it up from parents or elsewhere, shouldn't have been taught inches[1], as such the continued use of archaic units within the older reaches of the cycling community just goes further to alienate them.

Meters of development is not perfect, it doesn't take into account crank length for example, and far too many calculators give it to you in single decimal places (Sheldon's website does say it should be to 2dp). However for those bought up in a metric world, which is something in the region of 95% of the worlds population, it is the best system on offer.

After all, to 95% of the world? what's an inch[2]? 

J

[1] I appreciate that this hasn't quite worked out like that, but still.
[2] Useless trivia, to the 4.4% of the worlds population in the US, the inch is actually defined in law by it's metric value of 25.4mm. In law at least, the US is a metric country. For more info, the 99% invisible podcast did a great episode on it called Half measures - https://99percentinvisible.org/episode/half-measures/

--
Beer, bikes, and backpacking
http://b.42q.eu/

JennyB

  • Old enough to know better
Re: Does anyone know what gravel is?
« Reply #102 on: August 27, 2018, 12:41:57 pm »
So development in metres is roughtly 3/40 your gear in inches. Good to know.
Jennifer - walker of hills



Re: Does anyone know what gravel is?
« Reply #103 on: August 27, 2018, 12:50:51 pm »
Re gravel and gravel bikes, it's just the latest in rebranding of touring/general purpose bikes. The last time it was "cross", next time it''ll probably be "camping" then "trekking" etc.

Writers need something "new" to write about and the bike industry needs to sell new bikes.

Cudzoziemiec

  • Solar powered, tea fuelled cycle-wol
Re: Does anyone know what gravel is?
« Reply #104 on: August 27, 2018, 01:06:37 pm »
I'd agree that ERTO tyre designations are the One True Way, but, despite being fully metricated in my daily life (pints and miles perhaps excepted), gear inches do make sense; as mzjo points out, you end up with a useful range of between about 20 and 100, and quoting to the nearest exact inch gives a useful amount of precision. Yes, if you trace the origin back it's easy to be all 'hur dur penny farthing', but plenty of fields have weird customary units that work for their purposes; think wire gauges, gem carats, or typographic points. It's not like development, despite the apparent rationality, is actually all that useful in and of itself; to go from cadence to speed (whether m/s or km/h) still involves a conversion factor, meaning it's not any better from a mental arithmetic POV.

Except for the simple fact that outside the UK and the US, your average person doesn't know what an inch is. I described something to a Dutch work colleague the other day as 6 inches. He said "what's an inch?"

It's easy when you have been brought up with the abominable combination of units in the UK, to think everyone knows that an inch is 25.4mm, but the reality is, that noone does. For many who use gear inches for their gearing, it's purely because they are familiar with it. I wasn't bought up on it, and have to sit down and do maths to realise that a 28" gear is the same as my 2.1m gear (34/34 * 28).

...
Thing is, for the purposes of gear inches (as opposed to eg measuring Mars landers) you don't have to know that an inch is 25.4mm. Because in fact it's just a name for a numerical scale whose numbers indicate gear size. Higher numbers, higher gears. Just like you don't need to know that British shoe sizes are based on barley corns or European ones on a unit of 2/3cm in order to compare shoe sizes.

I'd also disagree that nobody outside UK and US knows what an inch is. My FiL, who spent his entire life in Poland, spoke in inches occasionally (usually referring to plumbing, I think, though he was an electrician). But it's certainly true that one system or the other seems better to us because we're used to it.


Inch-full photo taken (not by me) in a German supermarket.
The earth is vast and beautiful and contains many miraculous places. (Chekhov)

mattc

  • n.b. have grown beard since photo taken
    • Didcot Audaxes
Re: Does anyone know what gravel is?
« Reply #105 on: August 27, 2018, 04:36:21 pm »
Re gravel and gravel bikes, it's just the latest in rebranding of touring/general purpose bikes. The last time it was "cross", next time it''ll probably be "camping" then "trekking" etc.

Writers need something "new" to write about and the bike industry needs to sell new bikes.
Oh absolutely!

But isn't it nice that they're trying to sell us bikes that are actually good for quite a lot of real-world riding?  :thumbsup:

(If you already own such a bike and are happy with it ... well keep reading the reviews and feel smug! )
Has never ridden RAAM
---------
No.11  Because of the great host of those who dislike the least appearance of "swank " when they travel the roads and lanes. - From Kuklos' 39 Articles

Re: Does anyone know what gravel is?
« Reply #106 on: August 27, 2018, 04:59:34 pm »
Re gravel and gravel bikes, it's just the latest in rebranding of touring/general purpose bikes. The last time it was "cross", next time it''ll probably be "camping" then "trekking" etc.

Writers need something "new" to write about and the bike industry needs to sell new bikes.
Oh absolutely!

But isn't it nice that they're trying to sell us bikes that are actually good for quite a lot of real-world riding?  :thumbsup:

(If you already own such a bike and are happy with it ... well keep reading the reviews and feel smug! )
I disagree - the marketing is a re-branding of touring, which given it's long standing image is IMO probably a good thing.
The bikes are different and it's hard to see how anyone giving them more than a glance could conclude otherwise - geometry, weight, components - and it contributes in each case to a bike better suited to it's intended purpose.  Of course there's loads of overlap, there is with all bikes, but load up something sold as a Gravel bike with 30kg of luggage and it'll handle as well as a touring bike pushed to it's limit off road, both poorly.
I know, I know, people are going to tell us they used to ride on gravel before gravel bikes were invented*, so what? I'm a bit bored with hearing it.  You used to be able to get an obscure frame and pick and mix components to have a bike that looked like a dogs dinner and did just what you wanted, now you can get something better from Halfords, that's only a bad thing for those who think they've lost some elitism.

* or ride Audax before audax bikes were invented, or mountains before mountain bikes, or race before racing bikes, or tour before touring bikes...

Re: Does anyone know what gravel is?
« Reply #107 on: August 27, 2018, 05:09:00 pm »
After all, to 95% of the world? what's an inch[2]? 
We've had a referendum and we're taking back control, we don't care what the rest of the World understands, or if we have an economy, or any World trade, we have our British Inch and Blue passports. 
The People have decided, just accept it.

mattc

  • n.b. have grown beard since photo taken
    • Didcot Audaxes
Re: Does anyone know what gravel is?
« Reply #108 on: August 27, 2018, 05:40:32 pm »
Paul, you obviously have a lot of issues that are weighing on your shoulders.

Just get them out - we're here for you dude  :-*
Has never ridden RAAM
---------
No.11  Because of the great host of those who dislike the least appearance of "swank " when they travel the roads and lanes. - From Kuklos' 39 Articles

Re: Does anyone know what gravel is?
« Reply #109 on: August 27, 2018, 05:55:26 pm »
I'd agree that ERTO tyre designations are the One True Way, but, despite being fully metricated in my daily life (pints and miles perhaps excepted), gear inches do make sense; as mzjo points out, you end up with a useful range of between about 20 and 100, and quoting to the nearest exact inch gives a useful amount of precision. Yes, if you trace the origin back it's easy to be all 'hur dur penny farthing', but plenty of fields have weird customary units that work for their purposes; think wire gauges, gem carats, or typographic points. It's not like development, despite the apparent rationality, is actually all that useful in and of itself; to go from cadence to speed (whether m/s or km/h) still involves a conversion factor, meaning it's not any better from a mental arithmetic POV.

Except for the simple fact that outside the UK and the US, your average person doesn't know what an inch is. I described something to a Dutch work colleague the other day as 6 inches. He said "what's an inch?"

It's easy when you have been brought up with the abominable combination of units in the UK, to think everyone knows that an inch is 25.4mm, but the reality is, that noone does. For many who use gear inches for their gearing, it's purely because they are familiar with it. I wasn't bought up on it, and have to sit down and do maths to realise that a 28" gear is the same as my 2.1m gear (34/34 * 28).

Thing is if I know that my gear is is 5m of development, I can than easily work out that 5m x 90 rpm, gives me 450m per minute, x 60, gives me 27000m/h or 27kph. You can also do something same thing in reverse. "I want my top gear to allow me to do 50kph at 90rpm." 50000 / 60 / 90 = 9.26. divide by pi, then divide the wheel diameter (I'm using 0.7 just for simple maths in this example).  This gives you the ratio between your front and rear sprockets. If I want to decide on which chain ring to use, multiply by that, so if my cassette is fixed at 11, so what chain ring do I need.

50000/60/90/pi/0.7 * 11 = 46.3

46t chain ring. And if I have my 50t chain ring and want to decide on my cassette size, I divide the chain ring instead

50 / (50000/60/90/pi/0.7) = 11.875 so a 12 tooth realistically.

At risk of tying this to a discussion elsewhere on the forum anyone born after the mid seventies should have been brought up in an education system that is fully metric, they should have been taught m, cm, l, g, etc... and unless they picked it up from parents or elsewhere, shouldn't have been taught inches[1], as such the continued use of archaic units within the older reaches of the cycling community just goes further to alienate them.

Meters of development is not perfect, it doesn't take into account crank length for example, and far too many calculators give it to you in single decimal places (Sheldon's website does say it should be to 2dp). However for those bought up in a metric world, which is something in the region of 95% of the worlds population, it is the best system on offer.

After all, to 95% of the world? what's an inch[2]? 

J

[1] I appreciate that this hasn't quite worked out like that, but still.
[2] Useless trivia, to the 4.4% of the worlds population in the US, the inch is actually defined in law by it's metric value of 25.4mm. In law at least, the US is a metric country. For more info, the 99% invisible podcast did a great episode on it called Half measures - https://99percentinvisible.org/episode/half-measures/

System failure: your 28" wheel has a tyre height of 44.5mm and a total diameter of 711.2mm giving a dévelopment of 2.2352m with 34/34 (assuming you are on a 622mm rim - of course this figure will be correct only when your load compresses the tyre to give that diameter, the actual diameter could vary quite a lot with load at htese bigger tyre sections which is why vttists were always advised to set their bicycle computers by doing a rollout measure with the appropriate normal load).

Useless trivia - gold is sold in ounces, beer in pints and for a lot of french who weren't born when the franc changed "un bric" is still "un million ancien" (even now we have the euro.

I will have to check which are the official ISO units, I should know but there may be a few surprises.

Re: Does anyone know what gravel is?
« Reply #110 on: August 27, 2018, 06:46:30 pm »
Paul, you obviously have a lot of issues that are weighing on your shoulders.

Just get them out - we're here for you dude  :-*
As long as they're weighing in lb and oz I can handle it ;)

LittleWheelsandBig

  • Whimsy Rider
Re: Does anyone know what gravel is?
« Reply #111 on: August 27, 2018, 06:58:26 pm »
Not all touring bikes were/are loaded touring bikes, so not all traditional touring bikes handle 30kg of luggage very well.
Wheel meet again, don't know where, don't know when...

Re: Does anyone know what gravel is?
« Reply #112 on: August 27, 2018, 08:02:42 pm »
To return to an earlier post, what do the french call them I have this, extracted from "Le  650B", the magazine of the Confrérie



The relevant bit of text is in the rhs paragraph. Don't know that I have permission for this, don't know if I need it. The author is Christophe Courbou.

Kim

  • 2nd in the world
Re: Does anyone know what gravel is?
« Reply #113 on: August 27, 2018, 08:06:48 pm »
Be careful when using development to make gearing comparisons, particularly as here with fat tyres on a different rim size. A system  that relies on 10cm increments in wheel size tends to give misleading results (a comment that I have made to FFCT monitors on several occasions and which explains why the country that invented the metric system tends to avoid using the dévelopement measure)

What do they use instead? Gear inches seems to be a barbarian measure used by the US and the UK...

Gain Ratio (how far the bike travels for a given distance travelled by the pedal) is the One True Measurement of gearing.  Can't beat the purity of a dimensionless measurement that actually tells you what it feels like (development and inches are fundamentally flawed, as they disregard the mechanical advantage of the crank[1]).

I can't help feeling that thoughtless use of Gear Inches (or metric equivalent) is part of the 170mm-should-be-good-enough-for-anyone hegemony.


[1] And note that it's perfectly reasonable for the same rider to use different crank lengths on different types of bikes.  Why wouldn't you want a system that allows you to meaningfully compare the gearing of your track bike to your mountain bike?
To ride the Windcheetah, first, you must embrace the cantilever...

ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: Does anyone know what gravel is?
« Reply #114 on: August 27, 2018, 08:13:03 pm »
Kim wins again!!!!

Despite having grown up in the 70's and 80's, being an engineer, now working in the most archaic industry going (acre-feet anyone?) I have f@%k all idea what a gear inch is. 

My one true value is if I turn the pedals once, how far do i go? From that all else is true.
“Procrastination is the thief of time, collar him.” –Charles Dickens

Kim

  • 2nd in the world
Re: Does anyone know what gravel is?
« Reply #115 on: August 27, 2018, 08:15:45 pm »
My one true value is if I turn the pedals once, how far do i go? From that all else is true.

That's Development (whether you measure it in metres or milliFurlongs), and disregards the effect of crank length.


Tragically, unless I'm sitting down for a maths session, I have no sense of real-world values for gain ratio.  I've been known to calculate gear ratios in 170mm-crank-equivalent-inches in order to compare them.   :facepalm:
To ride the Windcheetah, first, you must embrace the cantilever...

LittleWheelsandBig

  • Whimsy Rider
Re: Does anyone know what gravel is?
« Reply #116 on: August 27, 2018, 08:17:01 pm »
Because I'm not using a track bike and a mountain bike for the same sort of riding, so their gearing will always differ. I'm only interested in how the gearing relates within each type of machine.
Wheel meet again, don't know where, don't know when...

ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: Does anyone know what gravel is?
« Reply #117 on: August 27, 2018, 08:19:28 pm »
My one true value is if I turn the pedals once, how far do i go? From that all else is true.

That's Development (whether you measure it in metres or milliFurlongs), and disregards the effect of crank length.

Boooo, Kim loses, suggest non- logical measure.

Crank length is irrelevant to how fast I'm going, only has an effect on knee upanddownness, which is a non-si unit.
“Procrastination is the thief of time, collar him.” –Charles Dickens

Cudzoziemiec

  • Solar powered, tea fuelled cycle-wol
Re: Does anyone know what gravel is?
« Reply #118 on: August 27, 2018, 08:20:18 pm »
To return to an earlier post, what do the french call them I have this, extracted from "Le  650B", the magazine of the Confrérie



The relevant bit of text is in the rhs paragraph. Don't know that I have permission for this, don't know if I need it. The author is Christophe Courbou.
Demain, on roule rackless á vélo gravier.
The earth is vast and beautiful and contains many miraculous places. (Chekhov)

Kim

  • 2nd in the world
Re: Does anyone know what gravel is?
« Reply #119 on: August 27, 2018, 08:22:40 pm »
My one true value is if I turn the pedals once, how far do i go? From that all else is true.

That's Development (whether you measure it in metres or milliFurlongs), and disregards the effect of crank length.

Boooo, Kim loses, suggest non- logical measure.

Crank length is irrelevant to how fast I'm going, only has an effect on knee upanddownness, which is a non-si unit.

Crank length is directly relevant to how hard you have to push on the pedals in order to get your bike moving, just like the rest of the system.  When cycling I'm more interested in force on the pedals than how fast they're turning.

If you're going to dismiss gain ratios as non-logical, you need to argue why another system is better.  The main arguments for the traditional measures are that they make the maths easier, or make intuitive sense to experienced penny farthing / unicycle riders.

You might as well argue that chainring size is irrelevant, as it only affects how fast the cranks are turning.  What matters is how far the wheel travels for a given amount of chain.
To ride the Windcheetah, first, you must embrace the cantilever...

Kim

  • 2nd in the world
Re: Does anyone know what gravel is?
« Reply #120 on: August 27, 2018, 08:25:11 pm »
Because I'm not using a track bike and a mountain for the same sort of riding, so their gearing will always differ. I'm only interested in how the gearing relates within each type of machine.

This is a reasonable argument, if you've committed sufficient n+1s that you don't need to compare to the gearing on a different class of bike you have experience of when specifying a new type.

While the track bike example is extreme, it seems perfectly reasonable to want to compare the gearing of, say, a prospective touring bike with a road or mountain bike you already have.  Given that it's a sometimes-useful thing to do (you could say that about comparing gear ratios at all), a unit of measurement that allows you to do it is better.
To ride the Windcheetah, first, you must embrace the cantilever...

Cudzoziemiec

  • Solar powered, tea fuelled cycle-wol
Re: Does anyone know what gravel is?
« Reply #121 on: August 27, 2018, 08:38:26 pm »
Every time somebody (and it is usually Kim) mentions gain ratio, I have to consult Sheldon to remind myself what it is and how to calculate and use it.
Quote
I would like to propose a new system, which does take crank length into account. This system is independent of units, being expressed as a pure ratio.

This ratio would be calculated as follows: divide the wheel radius by the crank length; this will yield a single radius ratio applicable to all of the gears of a given bike. The individual gear ratios are calculated as with gear inches, using this radius ratio instead of the wheel size.

An Example:
A road bike with 170 mm cranks: (The usual generic diameter value for road wheels is 680 mm, so the radius would be 340 mm.)

340 mm / 170 mm = 2.0. (The radius ratio)

2.0 X 53 / 19 = 5.58

This number is a pure ratio, the units cancel out. I call this a "gain ratio" (with thanks to Osman Isvan for suggesting this term.) What it means is that for every inch, or kilometer, or furlong the pedal travels in its orbit around the bottom bracket, the bicycle will travel 5.58 inches, or kilometers, or furlongs.

Given that you still have to pedal the cranks round a whole circle to get anywhere, I can't help feeling that useful as it is for giving a different view, it's not that much use without knowing how long the cranks are. Unless you're talking about an elliptigo or other push-pull mechanism cycle.
The earth is vast and beautiful and contains many miraculous places. (Chekhov)

Re: Does anyone know what gravel is?
« Reply #122 on: August 27, 2018, 08:50:10 pm »


At risk of tying this to a discussion elsewhere on the forum anyone born after the mid seventies should have been brought up in an education system that is fully metric, they should have been taught m, cm, l, g, etc... and unless they picked it up from parents or elsewhere, shouldn't have been taught inches[1], as such the continued use of archaic units within the older reaches of the cycling community just goes further to alienate them.



J

[1] I appreciate that this hasn't quite worked out like that, but still.
[2] Useless trivia, to the 4.4% of the worlds population in the US, the inch is actually defined in law by it's metric value of 25.4mm. In law at least, the US is a metric country. For more info, the 99% invisible podcast did a great episode on it called Half measures - https://99percentinvisible.org/episode/half-measures/

So you believe that kids should listen and learn what they are taught in school to the detriment of all else. If they had done that a couple of centuries ago there would never have been a metric system in the first place. I can think of quite a few dictators and other autocrats who would have definitely agreed with that.
Sorry hysterical historical background getting the better of me.
Interesting, that podcast. A bit aligned on the USAnians (for me a gallon is 4.45l or thereabouts) but interesting all the same. I once worked on a brand new factory installation with metric and imperial measures on the same plans. It was a bit of a disaster as installations go.

Cudzoziemiec

  • Solar powered, tea fuelled cycle-wol
Re: Does anyone know what gravel is?
« Reply #123 on: August 27, 2018, 09:09:59 pm »
I've read newspaper reports in Fiji about people having their houses demolished for road widening (big news in Fiji!) where the length of the road was given in km and the width in chains.
The earth is vast and beautiful and contains many miraculous places. (Chekhov)

Re: Does anyone know what gravel is?
« Reply #124 on: August 27, 2018, 09:17:35 pm »
Complaining about the use of inches on an English-language cycling forum seems to me to be rather, well, quixotic; however superior the mks system is for scientific and engineering calculation, the customary units aren't going anywhere, and will continue to be used (even if I suspect that, as for me, for many people of my generation an inch is 'about two and a half cm'). For hysterical raisins bikes are going to have weird hybrid metric/imperial dimensions for the foreseeable future. I'm surprised that QG's colleagues have no idea what an inch is; 'zoll' was fairly well known to the German and Swiss people I worked with, and I'd have thought anyone technical would have come across them, even only in the sense of 'weird USian legacy unit (see also feet, yards, miles...) that's a couple of cm large - check your databook for conversion factors'.

As Kim has pointed out, if you want a rational measure for gearing then gain ratio is the best, but, like development, I find the range somewhat unintuitive (& elegant though it is, I'm not entirely convinced it's necessary - one size up/down from 170mm is only 3% or so difference, and more than that suggests the riding will be different enough not to be directly comparable anyway).