Now, forgive my ignorance, but I'm not a very technical person (I'm an artist, don't blame me). From what I've gathered, dropping a tooth overall apparently helps a bike wheelie (my bud was changing out the sprockets on an R6, -1 tooth front and +2 in the rear and said that it would be a wheelie machine). But what does removing a tooth technically do? Does a monster require a different rear sprocket as well?
Removing a tooth from the front sprocket or adding teeth to the rear lowers the gear ratios, so for the same engine torque you get more force at the back wheel. The downside is you get that force at a lower speed. You know how you bike "pulls harder" in lower gears? "Lowering the gearing" is moving all the gears a little bit "lower". It effectively makes each gear a little closer to the one below it, so 6th gear is a little bit closer to what 5th used to be, 2nd gear is a little bit closer to what 1st used to be (and 1st is, I guess, a little bit closer to what an imaginary gear that was below 1st would have been).
Also, what does it mean when a bike is geared "tall"? I've heard it a couple times but I didn't bother to ask what it meant.
When people use "tall" like that, they're referring to the overall gearing being "high" (the opposite of what I discussed above, where 1st is a little closer to 2nd gear than desired). Lots of bikes (especially Monsters) commonly get accused of coming like this 'cause it helps them pass noise tests (which is a big deal for a manufacturer/importer).
And last question (for now) would be, what are the decimal numbers when people are reference the gears? IE I'll see a chart that lists 1st gear - .435 (some random number) and so on for the other 5 gears.
It's the ratio between the number of teeth on the pair of cogs that engage to make that "gear" - here's a pic of
a gearbox in all its internal glory - you can see the 5 pairs of cogs that mesh together ('cause this is a 5 speed box from a 750) - if you counted the teeth for 1st gear (the top right pair) you'd get 40t on the output shaft (the big gear) and 14t on the input shaft, which gives a ratio of 40/14 or 2.857 (sometime expressed as 2.857:1). 5th gear has 28t on the output shaft and 29 on the input, giving 28/29 or 0.966.
The "overall" gear ratio is the "primary drive" ratio (which is the gearing between the crankshaft and the input shaft of the gearbox, 61/33 for my bike), multiplied by the selected gear's ratio (40/14 for 1st, 28/29 for 5th), multiplied by the front and rear sprocket ratio (43/14 on my bike), so the torque I get at my back wheel in 1st is 61/33 * 40/14 * 43/14 or ~16.2 times bigger than the torque at the crankshaft (but turning 16.2 times slower).
When Ducati tell me a 750 makes 62Nm at 6500rpm, 16.2:1 means I'm getting 1005Nm at the back wheel, but only at 401rpm. That means I'd get a force (estimating 0.6m for my wheel radius) of 1675N, or about 170kg (376lb) at 48kmh (30mph) in 1st. In 5th, the overall ratio drops to 5.48, which means I'm only going to get 566N or 58kg (127lb) of force, but I'll get that at 142kmh (89mph).
So, have I confused you even more than you already were?
big
