To change gearing...whats better, front or rear sproket?

[300exHONDARIDER]

Since going to 20 inch tires on my 300ex, ive lost the top end. I get 42 according to my gps.
I've noticed that my back sproket is shot, so im going to change both sprokets and chain, and while im at it, i figured i might as well get some of my top speed back.
My choice is to go one higher on front, or 3 smaller on back.
I remember reading a gearing article a few years back, and cant find it now. Seems to me theres a difference in performance one way or the other. Assuming the gearing is 13-39, one tooth on front or 3 in back are mathmaticly identicle, but theres a differnce depending on which gets changed.
Anyone remember the article or the reasoning?

[GPracer2500]

It's better for the chain to increase the total number of teeth. And the larger the sprockets are the less friction the chain creates. It's not a big difference but something to consider. Where this can start to be significant is if you go real small on the front. I realize going smaller on the front isn't what you are considering but that may have been what you had read.

Sometimes you can get clearance issues with larger front sprockets but going 1 up is usually fine.

[rooster300ex]

I would go 1 more tooth up front and grind alil off of the case saver. 300ex gearing stock is 13/38. The rear sprocket you won't have to grind anything.

[bradley300]

1 tooth bigger in the front is what you need, or 3 teeth smaller in the back, its the same gearing either way. 1 tooth in the fron it equal to 3 in the back. the front is a more noticeable jump, the rear, you will barely notice 1 tooth

[JJ69]

so if i wanted more power.. i'd go for a -1 tooth front and +3 tooth back?... this confuses me. lol.

[wilkin250r]

Even going up 1 tooth in the front to a 14 will run into clearance issues with the stock case saver.

However, even with this problem I still recommend going up one tooth in the front, and grinding down the stock case saver to accomodate it. The larger sprockets will extend the life of your chain.

[bradley300]

Originally posted by JJ69
so if i wanted more power.. i'd go for a -1 tooth front and +3 tooth back?... this confuses me. lol.

a minus 1 tooth in the front or plus 3 teeth in the back would get the same result, more acceleration, less top speed

[2muchquad]

The larger sprockets will extend the life of your chain.

Will also extend sprocket life for the simple fact there will be more load bearing teeth.;)

[JJ69]

its only a 250x, it cant be real hard on sprockets anyway.
i dumped her in the ditch today and almost broke my neck.. hard ol whiplash.. harsh lol.. damn skipping sprocket.

what would happen if i put a +3 rear AND and -1 front? would it just not work as good?
i might just put stock back on the front and bigger in the back.. that'd be easier on the chain wouldnt it?

[400eXr1d3rZ]

Originally posted by JJ69


what would happen if i put a +3 rear AND and -1 front? would it just not work as good?


That would be like dropping 2 teeth in the front. Lots of torque.