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Author Topic: Sprocket theory  (Read 2105 times)

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Offline Hush

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Sprocket theory
« on: January 05, 2009, 07:33:13 PM »
OK so I'm running (on my 79 CB650PZ) a 40 tooth rear sprocket at present, what happens if I put a 36 tooth on?
Even better, what happens if I change the front sprocket from the present 16 tooth to a 17 tooth?
Combining these ie: 36 on rear and 17 on front, what would the forum expect my bike to do at town riding and at highway cruising?
Lots of theory, just something someone suggested to me and before I do it I wanted to run it past the forum members. ;D
"Runs to hide in bunker from sharp missiles."
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline cafe750

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Re: Sprocket theory
« Reply #1 on: January 05, 2009, 07:56:24 PM »
Basic sprocket theory.
To gear lower (numerically higher)
- Smaller front sprocket
- Larger rear sprocket
- Both

To gear higher (numerically lower)
-Larger front sprocket
-Smaller rear sprocket
-Both.

If you go with that 36 tooth rear, you won't spin as many RPM's on the freeway, but you'll also lose some low end grunt. You may lose enough to make it a complete pain in the a$$ to ride in town, due to the relative lack of gear multiplication.
If it's fuel savings you're after, gearing the bike "up" that much may take the engine out of its comfortable powerband, and lugging it everywhere your fuel consumption may go up.
Also, keep in mind that you may lose some clearance in the engine cases when you gain too many teeth on the countershaft sprocket, and that chains don't really like to turn too tight of a radius when you drop teeth on that front.

There's more, but thats a very brief overview, and I hope it helps!  ;)
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Offline Hush

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Re: Sprocket theory
« Reply #2 on: January 06, 2009, 12:22:16 AM »
Cheers for that Cafe 750, it's what i thought might happen.
Less revs of open road but the trade-off is less manoeverable gearing around town.
Was mainly for handling reasons, gas milage is tank to tank  ;D
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline KB02

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Re: Sprocket theory
« Reply #3 on: January 06, 2009, 04:06:39 AM »
Check out the "tip and Tricks" section. There is a post there with sprocket ratio calculators. Pretty cool stuff.
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Offline Really?

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Re: Sprocket theory
« Reply #4 on: January 06, 2009, 05:31:07 AM »
More studying to to, darn, lol.  For me I mean.
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Offline Triffecpa

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Re: Sprocket theory
« Reply #5 on: January 06, 2009, 09:49:41 AM »

one tooth +/- on the front is equal to about 3 teeth on the rear.  It takes about that much of a change for it to be really noticable.  Also, front sprockets are cheaper and have less of an impact on the length of your chain.

TR
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