is 3-1 the same resistance always?

[trippivot]

I'm thorwing around some options as far as the best sprockets to have in the box. My biggest question I wanted to throw out here is.

is 15- 45 the exact same as 16-48 as far as turning resistance (minus more chain for circumfrence)

15-46 is nearly the same as 16 49 and so on flirting with a 3-1 or decimally close to it.

3.06 3.07 -1

at the moment I have a 3.13 to 1 (15-47) but I know it will be too tall for the cold spring air.
just want some new ideas to reflect on. thanks.

[80GS1000]

Seems like bigger sprockets for a given gear ratio would have less resistance as the chain doesn't have to turn as sharply. Would be interesting to put a bike with 15-45 and then 16-48 on a dyno and see which makes more power...

[salty_monk]

But more mass to move as it's turning more sprocket & more chain.... would be interesting.

Dan

[rapidray]

Holy crap you must be bored Jeff!!! Ray.

[trippivot]

carbs are still at gast, got new type of rear tire, (TOYO) and the tracks are still closed up here.

With my 1-2-3 trans upgrade and the power jets in the 44's I'm sure I'll need a gear change.

some say the bigger C/S sprocket will help bite into the track better. Only thing to do is spend the money and test out for myself.

630 3" offset kosman 16 without a snout is what only $140 and a couple weeks to get it made.

[49er]

If you can get 16-50 for the 630 that's probably a good starting point. A larger radius on the front sprocket will reduce the amount of torque required by the engine to get the rear wheel rotating. If you find your too low on top end speed drop the rear back to 49 or 48 teeth.

[trippivot]

Thanks for the input 49'er

16-50 =( 3.12--1) and 16-49= (3.06--1)

these numbers are very close to the same pairs 15-47 and 15-46

now given the similarities of drive to driven ratio in theory they should require the same torque to begin movement from a standing still start.

HOWEVER I must correct the last response.... a larger diameter front sprocket will require MORE torque to rotate on it's own merit. With a larger rear sprocket in conjunction as a working pair the only real difference is the extra chain links to make it move together.

I do know what my next move is and I am very solid on the difference between theory and reality.

I wanted to begin a thread that might get some scientists brain mojo perculating.

I can put equations with circumfrence ~ diameter ~ weight ~ distance ~ porportion ~ all in direct relation to the sum of the parts of the final drive of a simple theoritic chain drive motorcycle. But that might be overkill for the average rider - tuner-

I want to travel 15,840 inches as fast as I can on a tire with a circumfrence of 81.64 inches. so I need to turn this wheel 194 times(194.02) to achieve this goal .

I am dealing with a #720 package and around 200 HP, shifting @10K rpm, a inner reduction (clutch~crank) , a 5 speed transmission , and finally followed by an outer reduction (final drive).

so are you smarter than a junior high schooler? I wonder about myself sometimes. trip pivot's brain starts smoking right now

[Steve]

trip pivot's brain starts smoking right now

.

[Roger P.]

Thanks for the input 49'er

16-50 =( 3.12--1) and 16-49= (3.06--1)

these numbers are very close to the same pairs 15-47 and 15-46

now given the similarities of drive to driven ratio in theory they should require the same torque to begin movement from a standing still start.

HOWEVER I must correct the last response.... a larger diameter front sprocket will require MORE torque to rotate on it's own merit. With a larger rear sprocket in conjunction as a working pair the only real difference is the extra chain links to make it move together.

I do know what my next move is and I am very solid on the difference between theory and reality.

I wanted to begin a thread that might get some scientists brain mojo perculating.

I can put equations with circumfrence ~ diameter ~ weight ~ distance ~ porportion ~ all in direct relation to the sum of the parts of the final drive of a simple theoritic chain drive motorcycle. But that might be overkill for the average rider - tuner-

I want to travel 15,840 inches as fast as I can on a tire with a circumfrence of 81.64 inches. so I need to turn this wheel 194 times(194.02) to achieve this goal .

I am dealing with a #720 package and around 200 HP, shifting @10K rpm, a inner reduction (clutch~crank) , a 5 speed transmission , and finally followed by an outer reduction (final drive).

so are you smarter than a junior high schooler? I wonder about myself sometimes. trip pivot's brain starts smoking right now

Depending on how anal you want to get, remember that the rear tire will not be perfectly round due to flattening of the tire from the weight of the bike, so your true tire circumference will be pi * effective diameter of the tire as measure by taking the center of the axle to the pavement and multiplying that by 2, which will lower your gearing a bit, at least at launch.

[rapidray]

720# package? Holy CRAP Jeff!!! Who's the pig, you or the bike?!!! I don't believe that bike is over 430 pounds! That makes you 290?!!! Ray.

[trippivot]

the bike is #460 I'm #230 and the super hero suit ensamble weigh #20 at least!!

yeah I'm every bit of 700 pounds at the line.... oink'


great detail Roger!!! The traction patch!!! That is one of the exact details where reality and theory differ from one another!!

I ran a 15 47 all last year and depending on the humidity the shift light in hi gear came on at the finish line or @ the mph cones so , I was "in the range" I'll be very close starting with a 15 46 combination but I'll be carrying more momentum with the no kill "123auto" through the first 2 gear changes may require a larger change.

that is going to take me right up to the choice of 15 45 or it's equal 16 48. this is why my question becomes relavant . money is not an object so if 16 48 makes more benefit to run over a luggy 15 45 I'll make the change.

maybe vice versa is the case? Hell I have a box of Kosman sprockets already. I love the drag racing

[FJman]

Don't normally read here or post much, but this is the sort of silly thing I think about, so here's what I've come up with about it:

The major difference between 15/45 and 16/48 is a subtle one.

-The bigger gears weigh more and require a longer chain to wrap around. This is going to add some rotational inertia. It's a pretty small amount though, when you realize what a wheel and tire weighs.
-The bigger gears will have a little less drag due to the bigger radius that the chain is going around.
-The smaller gears will have a little less friction between the chain and sprockets themselves, but there is going to be more tension on the chain. That tension is going to show up as more heat into the chain, as well as a smaller area to cool it and less thermal inertia (less metal involved to take the heat, as well as less area to radiate it away).

None of these are really a big difference in any way, and may not even be measurable. Looking at these, the easy answer is to use the bigger set, because you're going to gain reliability and the rate of wear is slower, so the chain stays in good condition longer, keeping the bike quicker for longer.

The geometry changes a bit though also. A bigger sprocket set puts the chain up higher away from the axle/countershaft centerline, which relative to the swingarm pivot point changes things. Doesn't really matter, as the chain with more tension (smaller countershaft) is going to end up putting the same load into the suspension once everything is loaded up.

What does change is the correct chain slack, because of the different amounts of tension involved. It'll be more noticable if you're running a longer arm on the bike, having a greater difference in tension on the chain between fully loaded (launching the bike) and resting.

Still would use the bigger set in a drag situation or in a touring situation.