Gear Chart For The Track

Where speeds may exceed 60 kmph

Gear Chart For The Track

Postby foo on patrol » Sat Aug 24, 2013 7:12 am

Here you go, all the combos you need for racing. :mrgreen:

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Last edited by foo on patrol on Sat Aug 24, 2013 12:04 pm, edited 1 time in total.
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by BNA » Sat Aug 24, 2013 7:14 am

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Re: Gear Chart For thr Track

Postby foo on patrol » Sat Aug 24, 2013 7:14 am

Hmmmmmmmm it cut off the last bit of it! :?

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Re: Gear Chart For thr Track

Postby familyguy » Sat Aug 24, 2013 10:56 am

Right click, save as. Whole chart.

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Re: Gear Chart For thr Track

Postby briztoon » Sat Aug 24, 2013 11:47 am

Coming from an idiot.

How do you read it?
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Re: Gear Chart For thr Track

Postby foo on patrol » Sat Aug 24, 2013 12:03 pm

Top line is your chain ring and vertical is sprocket. You just follow each number till they meet, same as a graph you idiot. :lol:

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Re: Gear Chart For The Track

Postby briztoon » Sat Aug 24, 2013 12:16 pm

I understand that. What I do not understand is what each figure on the graph represents, and why some are coloured blue, green and red.
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Re: Gear Chart For The Track

Postby vander » Sat Aug 24, 2013 12:27 pm

>80 Red <65 blue inbetween green, cant tell you why but, wouldnt be racing (except maybe outdoors but even then I wouldnt personally) on <90".
Better off going to sheldon brown and putting in the common chainrings 49,50,51 and 13,14,15 cogs. Much more succinct easier to read table. Maybe even 2 printouts next to each other 48,49,50 and 51,52,53 (or similar).
http://sheldonbrown.com/gears/
I even find this one easier to read - http://www.aboc.com.au/tips-and-hints/t ... gear-chart and goes up to 55 (not that I know when you would really need 55 except maybe road TT)
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Re: Gear Chart For The Track

Postby foo on patrol » Sat Aug 24, 2013 12:59 pm

briztoon wrote:I understand that. What I do not understand is what each figure on the graph represents, and why some are coloured blue, green and red.


Are you talking about the Skid Graph? The top one is the one I would refer to which = roll out.

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Re: Gear Chart For The Track

Postby foo on patrol » Sat Aug 24, 2013 1:04 pm

My chain rings were 46, 47, 48, 49, 50, 51 and 52 on the track and gave me a range from 86 - 92.6. :)

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Re: Gear Chart For The Track

Postby dalai47 » Sat Aug 24, 2013 1:27 pm

Outdoors depending on the events and field size I'll race using 88 - 94, indoors 94 - 98...
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Re: Gear Chart For The Track

Postby briztoon » Sat Aug 24, 2013 2:12 pm

Yes the top chart. But what do the figures in blue, green and red represent. Where do the numbers come from, and what do they mean. I see the chart, but do not know what I am looking at. Can you explain the chart to a beginner?
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Re: Gear Chart For The Track

Postby vander » Sat Aug 24, 2013 2:39 pm

Oh its gear inches, its a measure of the size of the gear you are using, as you can see all of us are happy to talk in inches (rather than the exact gear). Not exactly sure how they figure out how an inches a gear is, maybe someone else can say that. All the numbers that are the same are exactly the same size gear i.e. one pedal revolution will cause exactly the same amount me meters gained.

Its a way of talking about gears, that actually make things quite easy.

For the others, indoors I have been using 102-105" recently and have seen an improvement after going up. I found (AT) ~96 was OK for most the race but at the end I was maxing out my RPM (for me in the high 130s) and couldnt spin any faster.
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Re: Gear Chart For The Track

Postby DoogleDave » Sat Aug 24, 2013 2:53 pm

vander wrote:.....Not exactly sure how they figure out how an inches a gear is, maybe someone else can say that......


Calculating Gear Inches :-)

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Re: Gear Chart For The Track

Postby foo on patrol » Sat Aug 24, 2013 2:57 pm

briztoon wrote:Yes the top chart. But what do the figures in blue, green and red represent. Where do the numbers come from, and what do they mean. I see the chart, but do not know what I am looking at. Can you explain the chart to a beginner?


You multiply the wheel size by the chain ring and divide by the rear sprocket. eg; 27x52 div 15 =93.6 You use the 27" wheel size even for 700cc. 700cc is actually the same size as the old singles/tubs. :wink:

The gear size = one full revolution of the pedals as you would realise. :) Hope this helps explain things for you. :?:

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Re: Gear Chart For The Track

Postby Alex Simmons/RST » Sun Aug 25, 2013 8:21 am

Gear inches as shown in the top half of the chart is a way to express the equivalent wheel diameter if it were a penny farthing front wheel (which has cranks directly attached to the wheel, hence the wheel's size is the gear size).

Rollout is a different but related value, and is how far the bike moves for one full crank revolution (or the equivalent of the circumference of an equivalent penny farthing wheel).

The use of gear inches is just a traditional way of expressing a gear size, and most track and fixed gear riders will be familiar with this terminology as it tends to get handed down, mainly because they can only choose to put one chainring and one cog on their bike at a time, so need to work out what size gear they want to use.

e.g. a 50x15 gear = 90" and one crank revolution would move the bike 90" x Pi (3.14159) = 282.7" = 7.18 metres
Junior riders in Australia will be familiar with rollout, as junior racing has maximum rollout restrictions.

However this is on the assumption that a nominal standard wheel is 27" in diameter, which is rarely the case, and most modern road and track bikes have wheel diameters a bit less than that, so a true gearing chart should also account for your actual wheel circumference. Hence why when checking a junior rollout, we don't just look at what chainring and cog are used, but actually roll the bike backwards to see how far it travel for one full crank revolution.

e.g. a wheel with a race tyre may have a circumference of 2.096m = 82.5" = diameter of 82.5/Pi = 26.3"
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Re: Gear Chart For The Track

Postby ldrcycles » Sun Aug 25, 2013 10:14 am

Why such short gears? I have a 100" top gear on one of my steel bikes and if i'm getting into it on the flat that's about right for me, the next gear down is 82.6" and way too short for more than about 40kmh.
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Re: Gear Chart For The Track

Postby Derny Driver » Sun Aug 25, 2013 10:47 am

ldrcycles wrote:Why such short gears? I have a 100" top gear on one of my steel bikes and if i'm getting into it on the flat that's about right for me, the next gear down is 82.6" and way too short for more than about 40kmh.

This is a gear chart for track racing.
Track is different to road. Its not hard to push 100 on a road bike for a short distance.
If you can do 12 laps of a flat 250 metre track on 102", from a standing start, cadence 110, in about 3 and a half minutes you would be Australian Master pursuit champion and possibly a world champ too.
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Re: Gear Chart For The Track

Postby foo on patrol » Sun Aug 25, 2013 11:21 am

ldrcycles wrote:Why such short gears? I have a 100" top gear on one of my steel bikes and if i'm getting into it on the flat that's about right for me, the next gear down is 82.6" and way too short for more than about 40kmh.


You need to learn how to spin Idry. :wink:

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Re: Gear Chart For The Track

Postby briztoon » Sun Aug 25, 2013 1:16 pm

Alex Simmons/RST wrote:Gear inches as shown in the top half of the chart is a way to express the equivalent wheel diameter if it were a penny farthing front wheel (which has cranks directly attached to the wheel, hence the wheel's size is the gear size).

Rollout is a different but related value, and is how far the bike moves for one full crank revolution (or the equivalent of the circumference of an equivalent penny farthing wheel).

The use of gear inches is just a traditional way of expressing a gear size, and most track and fixed gear riders will be familiar with this terminology as it tends to get handed down, mainly because they can only choose to put one chainring and one cog on their bike at a time, so need to work out what size gear they want to use.

e.g. a 50x15 gear = 90" and one crank revolution would move the bike 90" x Pi (3.14159) = 282.7" = 7.18 metres
Junior riders in Australia will be familiar with rollout, as junior racing has maximum rollout restrictions.

However this is on the assumption that a nominal standard wheel is 27" in diameter, which is rarely the case, and most modern road and track bikes have wheel diameters a bit less than that, so a true gearing chart should also account for your actual wheel circumference. Hence why when checking a junior rollout, we don't just look at what chainring and cog are used, but actually roll the bike backwards to see how far it travel for one full crank revolution.

e.g. a wheel with a race tyre may have a circumference of 2.096m = 82.5" = diameter of 82.5/Pi = 26.3"


Thank you Alex. I sort of understand what your explaining. Unfortunately my brain tends to shut down when math is involved. I'm the type of person if it's explained to me in person and demonstrated at the same time, I get it. But I struggle to conceptualise things such as this.

Can you explain why different figures are in different colours please.
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Re: Gear Chart For The Track

Postby briztoon » Sun Aug 25, 2013 1:23 pm

So if I am riding my road bike in it's 53 chain ring, with an 11 cog, I'll roll 130.1 inches or 3.3 meters with one revolution of the pedals. :?:
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Re: Gear Chart For The Track

Postby foo on patrol » Sun Aug 25, 2013 1:25 pm

Yup that be it. :mrgreen:

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Re: Gear Chart For The Track

Postby familyguy » Sun Aug 25, 2013 1:37 pm

briztoon wrote:Thank you Alex. I sort of understand what your explaining. Unfortunately my brain tends to shut down when math is involved. I'm the type of person if it's explained to me in person and demonstrated at the same time, I get it. But I struggle to conceptualise things such as this.

Can you explain why different figures are in different colours please.


Red: track ratios
Green: probably about right for street use
Blue: pretty small, not for track, maybe for street

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Re: Gear Chart For The Track

Postby jaffaman » Sun Aug 25, 2013 2:00 pm

briztoon wrote:So if I am riding my road bike in it's 53 chain ring, with an 11 cog, I'll roll 130.1 inches or 3.3 meters with one revolution of the pedals. :?:


No, actually you will roll 130,1" x pi =408.7" = 10.38 metres. Circumference = pi x diameter. Which if you work it out at a cadence of 90 turns / min = 10.38 metres x 90 x 60 mins/hr = 56.06 kms/hr.
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Re: Gear Chart For The Track

Postby foo on patrol » Sun Aug 25, 2013 2:48 pm

Not a hope in hell that a 130" gear will roll out to 10.38 metres. :?

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Re: Gear Chart For The Track

Postby Derny Driver » Sun Aug 25, 2013 3:55 pm

briztoon wrote:
Can you explain why different figures are in different colours please.

What Jim said.
It looks like Foo has lifted this chart from a fixie site. Some fixie freak has coloured green the gear combinations which are great for street riding. Red are too big a gear and blue too small. So when setting up your street fixie you want a gear combination of around 70 odd gear inches.
The skid chart has been added. When choosing your chainring -cog combination which is in the vicinity of 70ish, you want to avoid the combinations on the second chart which have a number 1. That means when you lock up your rear wheel, it will always skid in the same 1 spot on the tyre. That tyre wont last long before it pops. The combinations which say 21 are best as you will flat spot 21 different places on the tyre when you skid, which means your tyres will last longer.
Fixies with road dropouts have a big problem with chain length. so you need to find a chainring -cog combination which is in the green zone, doesn't have a slack chain, and maximises as many skid patches as possible. Fixie freaks have lots of other difficulties too like deciding which skinny jeans to wear and how to keep their cards from falling out of the spokes. But that's another topic.
For track use you can forget the colours. And the skid spots.
There are no rollout distances on this chart. You can find rollout charts on the cycling nsw website.
For all intents and purposes gear inches are just a meaningless number which date back to the days of penny farthings. You just use the numbers to compare which gears are numerically larger or smaller than each other.
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