registered as a moped, yes. but not really a moped. a moped has a MOtor and PEDals. MO-PED. a 49.4 cc vespa is still a scooter not matter how you slice it.

I don't measure chain use in months or years but by the mileage... I was riding enough last year to warrant chain replacements every 2 to 3 months.

this is why i use the wonderfully random ratio of 44x17. i do have about 8 well defined skid spots, but i think that is how all 17 of them blended (some are only 2-3 inches long, others are 8-10 inches long. i also skid with either foot, and don't hold it in one spot while skidding. sometimes i like to backpedal a bit. it makes life more fun. i still don't know why people use 3:1 and 4:1 ratios. just tweak it a bit and learn to pedal a bit harder, or spin a few rpm more. your body will adapt.

people run 3:1 because all these cheap completes running around come stock with a 48x16 ratio

I went down a tooth to a 15 on the back and went up two teeth to a 50 tooth when I got my current fixed gear. I tried 48x16 on my old schwinn right before it was stolen and didn't like it.

50x15 gear is 3.3333333333333333:1

Tabor, post a pic, any pic of any modern bike with a rear cog with three times as many teeth as the front cog. I'd love to see it but I just don't think they are common.

You missed the whole point that a mathematical ratio doesn't care which side the front and rear cogs are on.

EDIT- Post a pic of a math book that says the otherwise.

BS. All ratios for gears mean (First input): (second imput) .Its the standard for any ratio of gearing.
3:1= three turns of the crank, one turn of rear sprocket on a bike, 3 turns of the crank means one turn of the output shaft in a transmission, and 3 turns of the output shaft/driveshaft of a car= one revolution of the axles after going through the differential.

Heres a mathmatical "proof" if you will, since you want proof mathwise.
R= i/o w
here R=Ratio, , I=Input=crank RPMS and O=output=wheel rpms
30/90=3/9= 1/3
1/3:1= (1/3)*3 : (1)*3=1:3
90/30=3, which is 3:1 ratio

His ratio is wrong.

30:90 crank/wheel(what he described) That kind of gearing would be impossible to ride. Even a road bike triple with a 30t "granny gear" front and 23t rear is only a 1.4:1 gear ratio, and thats impossible to spin unless your going up a steep road.

Even a worn chain shouldn't bust like that.

I've gotten 600 (dud chain), 3500 (still going), 4000, 5000 and 7500 miles out of chains on my fixed gear bicycle before reaching 'stretched' indicator on check gauge.

Dry weather and clean roads are most important for chain life (assuming same cleaning schedule)

Al

How on earth do you folks keep track of how many miles you've put on a chain?

Maybe you are correct that there is a defacto standard in the engineering community for input gears and output gears. But you are still arguing semantics. It is a ratio between two numbers.

1 turn of the wheels : 4.11 turn of the driveshaft

and

4.11 turn of the driveshaft : 1 turn of the wheels

are mathematically identical.

Do you have a math degree? Because I do.

Some folks have odometers on their bikes, even their fixed ones.

no doubt. wtf is up with that advice? hilarious.

Skipped the part on induction did you? I'd argue that given a ratio of x:y and the information that y is never >3x and rarely greater than x that it is easy to determine what is meant even if the ratio is presented in the opposite order.

In construction, a 3:1 fill slope (3' horz. for every 1' vert.) is alot different than a 1:3 slope (quite steep).
So I would expect a gear ratio to be assumed to be front/rear, never thought it would be taken otherwise.

...because bikes are piles of dirt.

Sources?

This sounds more reasonable: https://www.sheldonbrown.com/chain-life.html

A track chain lasts a lot longer if you set it up so that the ratio of chainring teeth to cog teeth is a step in the Fibonacci sequence. It's a mathematical law of nature.

Buy a chain checker/chain wear indicator and don't be a ******. 3 years on a regularly ridden chain is stupid. Chains are cheap. I replace mine about every 6 months!

^ here, here. Even with brakes, or even a road bike, a broken chain can cause serious injury. Depending on mileage and the road/weather conditions, I replace my chains 1 or 2 times per season. And that isn't even for safety: the chain is cheaper than the rest of the drivetrain and you only need to see what a worn chain can do to the chainring to understand. When I worked in the shop, I'd see rings that looked like sawblades the wear was so uneven...
chain = $
ring = $$$
chain = hard
ring = soft

Good for you, you defined units so the ratio in you example would be wrong.

What part of "you are only changing the units" don't you understand?

Damn, all this argument over something that everyone involved already understood.

I like ur username!!!11~

Question about chains...I ghetto rigged a fixie on an old peogeot by screwing on a 19 tooth surly cog and an bb lockring, shortening the chain and running the chain through the inside chainring. The problem is that is doesnt seem to "flow" arount the rear cog, looks like it doesn't fit or something. The info I read online abou the Surly cog was that is could handle all chains...suggestions? help?

https://harriscyclery.net/itemdetails.cfm?ID=2195
Surly cog...