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.
130 is just a number. Big number = hard gear to pedal. Small number = easy to pedal.
Gear Chart For The Track
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Re: Gear Chart For The Track
No. 130 is just a number. Big number = hard gear to pedal. Small number = easy to pedal.
Re: Gear Chart For The Track
That's exactly the rollout it will have. Rollout = gear x Pi gear = wheel diameter x chainring teeth / cog teeth In this case a 27" wheel x 53 chainring / 11 cog = 130.1" gear The rollout of such a gear would then be 130.1" x Pi = 408.7" = 10.38m
Re: Gear Chart For The Track
It's gearism, and shoud be banned. Really though, someone has simply chosen to aribtrarily colour code the gears according to three size categories. Small, medium and large, with gear sizes of 65" and 80" being the artitrary cut over points for each category. As DD says, it's a guide to gears suitable for a road fixed gear bike. The skid patches is a bit different, and just a way to then not only choose the gear you like using the upper half of the chart, but one that will also over time more evenly wear the rear tyre out should you choose the skid the bike for braking. The higher the skid patch number, the more evenly you'll wear the rear tyre if you brake that way. A low number will see skids wear the same patch of tyre out and the useful life of the tyre will be much shorter*. Of course just using brakes would be much better, but we are not talking about sensible cycling here. * It should come as no surprise that the chain rings with consistently highest numbers of skid patches are prime numbers.
Re: Gear Chart For The Track
Ok I'm confused now. I have always been of the belief that it was one full 360 revolution of the pedals! Foo I don't suffer fools easily and so long as you have done your best,you should have no regrets.
Goal 6000km
Re: Gear Chart For The Track
It is. Lets simplify it for ease of working. Say your front crank is a 55 and the rear is on an 11. Every time you turn the pedals 360 degrees, you move 55 chain links. At the back, the 55 links will spin the rear 11 tooth cog around exactly 5 times. So, one turn of the pedal, the wheel goes around 5 times. If the wheel is 27" then In gear inches we would call this case as being 5x27 = 135 gear inches. In terms of distance travelled, each time the wheel goes around it will go 27" x pi on the ground which is 84.8" or 2.15 metres. Try it. Roll your wheel around and see how far it is. So then. One turn of the pedals is 5 turns of the wheel and in this hypothetical case rollout is 5x27" x pi (135 x pi) inches which in this case works out to 424.1 inches or 10.75 metres.
Re: Gear Chart For The Track
The gear ratio gives you the number of times the cog will rotate for one revolution of the chainring. If you were running a 100 tooth chainring and a 25 tooth cog (for the sake of simplifying numbers), then one revolution of the chainring will give you 4 revolutions of the cog (100/25). If you had 20 teeth on the back, you would get 5 revolutions of the cog for one of the chainring, and so on. To get the distance that represents you need to know the circumference of the wheel, since each time the cog turns the wheel will turn as well. The circumference is Pi times the diameter. So we have Alex's equation of: Rollout = wheel diameter x Pi x chainring teeth / cog teeth
Re: Gear Chart For The Track50x15 = 90 inches.
Therefore, 1 chainring tooth = ~2 inches, and one sprocket tooth = ~6 inches.
Re: Gear Chart For The TrackYep ok, just goes to show you're never to old too learn!
Foo I don't suffer fools easily and so long as you have done your best,you should have no regrets.
Goal 6000km
Re: Gear Chart For The Track
Ahh that's why. My preferred cadence is significantly slower, more around 90rpm, entering that into Sheldon's calc for my 52-14 gives 43.3kmh, which is exactly where I feel most comfortable on that bike. Out of interest, I changed the cadence to 120 and got a figure of 57.8kmh, definitely getting pretty quick there! When man invented the bicycle he reached the peak of his attainments- Elizabeth West.
Re: Gear Chart For The Track
90 is about right for road riding. In an individual pursuit on the track the optimal cadence is around 106-108. From a standing start getting a 100 inch gear up to around 56kph in half a lap takes a big effort. Then the rider settles back to around 52 kph at that cadence around 105-110 and has to do 11 and a half more laps without losing any speed at all. For me, I find individual pursuits and points races the most fascinating to watch.
Re: Gear Chart For The Track
Great to watch, hard to race well...
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