Something to ponder...

[M.F.D.B.]

Ok, lets talk hypotheticaly.

You have 2 identical bikes, with 2 identical FINAL DRIVE GEAR RATIOS.

HOWEVER, one bike has a pretty large (lets say, 15/53 tooth) front and rear sprockets and the other has a pretty small front and rear sprockets (like a 12/42). But again, the final drive gear ratio is THE SAME (3.5ish:1.

Pros and cons...

My experience (and many of my peers) is the smaller you go in the front, the exponentially worse it is for chain wear (the chain now has to change directions in a shorter time/distance increasing wear).

So question is: The bike with the smaller gears in theory should make more power to the ground, since there is less chain links, and smaller gears spinning (lets make this thread simple and not discuss the other benefits such as moment of inertia, rotating mass, braking effect, etc.) as compaired to the bike with the larger gears. But what effect on performance is there besides the increased chain wear?? Obviously if there is increased wear on the chain, then it takes energy to cause that wear, so do the gains outway the losses??

In laymans terms, is it better to go smaller or larger if the end result (gear ratio) stays the same??

[redrocket190]

My instincts tell me the gains are negligible and my experience tells me small(er) sprockets really eat chains fast. I would choose a 3T larger rear sprocket over a 1T smaller counter shaft sprocket. Conversely I would gear up with a larger counter shaft sprocket at least until I was running +2T.

[AlisoBob]

You should always run the biggest front sprocket for your desired ratio.

Chain friction, wear, and swingarm slider wear will all be considerably reduced.

[dannygraves]

dewayne was telling me he runsa a 13/34 I believe and the rear is costom made, can't remember who makes it. He swears the weight reduction makes a big difference.

[dannygraves]

of coarse, his is a RACE bike, so wear is not a concern, winning races is!

[britincali]

Anytime you have something wearing its using power to wear it.

[MICK]

Anytime you have something wearing its using power to wear it.

Yes but at times the power gained is greater than the power lost due to wear.
Can we use a typical o-ring chain vs a non o-ring chain for this comparison? The non o-ring chain won't last as long, but it damn sure puts more juice to the dirt.

But ultimately I don't see that running a couple less links and smaller sprockets is going to save that much weight. I would think a couple ounces at best. Not a negligible weight savings I believe for the reduced chain life.
Now take for instance a super bike. Converting drive components to a 520 pitch chain and sprockets and dropping the counter shaft a tooth makes a phenomenal improvement. Taking 1.5 - 2.0 lbs of rotating mass out of the drive system and closing the bike's wide gear spacing IS a cost effective upgrade.

I thought about doing something similar to the 500. Converting to a 420 pitch drive system with a 10000 lb or stronger chain might save a pound. But a person could just spend $60 on an aluminum sprocket and shed a pound as well. Then take his girl out with the money he saved.

[M.F.D.B.]

Good example, as I have converted my CBR1000RR to 520 and there was a significant increase in performance. The fact that my bike has 150+hp at the rear wheel and much better traction then a dirt bike, got me interested in converting my dirt bike to a smaller chain. But before I did I watched a friend snap his chain and punch the case (Jeffcr500) so I was reluctant after that!!

[Roostius_Maximus]

Lighter the chain is always beter, cross drilled, non o-ring, and on less links makes it faster, and if you're looking for the faster parts be ready to do some maitinence