Can someone explain the physics behind the gears? My guess is that the gears in the front are the “driving” gears (always bigger than the rear gears) so bigger the harder? Then if rear gears are bigger than the front gears, then it would be the opposite? Please enlighten me!
If the small gears were up front, you’d be spinning 2500 rpm to go 35 mph! (Assuming 53x11 ~ 35 mph @ 100 rpm.)
Something like this
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It’s all 'bout the ratio, 'bout the ratio!
In other words, how many revolutions of the rear wheel are made with one revolution of the cranks. Increase the number of teeth in the front chain ring (make it bigger) and the rear will travel further with each revolution. Increase the number of teeth on the back though and you’ll won’t go as far. Think of it this way.
If this doesn’t make sense, think of it this way. Start with, lets say a 50 tooth front and a 50 tooth rear, every full pedal rpm results in one full revolution of the rear wheel (1:1 ratio). Now, if you change the rear to 25 teeth, every full revolution on the front results in 2 full revolutions on the back. Alternatively, if you keep the rear at 50 and halve th front to 25, one full revolution of the front results in only 1/2 a revolution of the rear.
Ah I see. But then in the picture above, what’s the point? I don’t know the exact gear ratio, but from the looks of it, it seems pointless to have this setup? The rear big cog looks similar in size of maybe a compact front gears and the front crankset looks like 27 maybe in the low 30s? In other words, the picture above looks like a standard setup just with the front and rear ratio reversed?
Ah I see. But then in the picture above, what’s the point? I don’t know the exact gear ratio, but from the looks of it, it seems pointless to have this setup? The rear big cog looks similar in size of maybe a compact front gears and the front crankset looks like 27 maybe in the low 30s? In other words, the picture above looks like a standard setup just with the front and rear ratio reversed?
I mean, that gearing would let you go 100mph… up until your legs rip off
Ah I see. But then in the picture above, what’s the point? I don’t know the exact gear ratio, but from the looks of it, it seems pointless to have this setup? The rear big cog looks similar in size of maybe a compact front gears and the front crankset looks like 27 maybe in the low 30s? In other words, the picture above looks like a standard setup just with the front and rear ratio reversed?
I mean, that gearing would let you go 100mph… up until your legs rip off
Umm…nope. That setup will let you go 5mph up a hill. Until your legs rip off. And to the OP, that’s the purpose of a small in front and a big in back, is to go uphill.
Umm…nope. That setup will let you go 5mph up a hill. Until your legs rip off. And to the OP, that’s the purpose of a small in front and a big in back, is to go uphill.
Opps. More like you would fall over for going 3mph.
Someone should’ve payed attention in grade school.
It appears your use of "crank"bait has reeled in a lot of fish:)
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In Australia it’s the opposite, due to the Coriolis effect bigger gears in the front make you go slower.
This line has made my top 10 list for 2014
F’n funny stuff
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In Australia it’s the opposite, due to the Coriolis effect bigger gears in the front make you go slower.
Is that why? I always thought it was because we rode upside down.
This is something I wrote for SportTracks a while back explaining exactly what you’re asking:
http://sporttracks.mobi/blog/theoretical-building-blocks-gearing
It has to do with the the ratio of angular velocities and radii, which I promise, are not impacted by the rider’s location with respect to the Earth’s hemispheres.
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That’s brilliant, must be from one of those “backward” countries.
ok,
Ive found the best way to explain gearing is… think of it as a lever, you know how a lever works right?
imagine it in terms of, the front ring is the part of the lever from the pivot to the load you are trying to move… if you make this part longer/bigger it gets harder to move, but will move furthur for a given input.
the rear cassete cogs are then the part of the lever from where you input force to the pivot, making these larger will make moving the object easier, but wont move it as far for a given input…
just like a lever, if both cogs are the same size(no of teeth) the ratio will be 1:1 which is ok for a laden tourer going up somthing like a 10% grade, but on the flat you want a lot more teeth on the front ring by around 3 times, so say 17 teeth on the wheel, and 51 on the pedals, thats the right ball park for a single speed