SPROCKETS...

[SMOKIN66]

HEY GUYS, I JUST ORDERED NEW SPROCKETS,OLD ONES WERE LEANIN OVER ALIL TOO MUCH- I ORDERED SUNSTAR- 13 TOOTH FRONT, 49-REAR, AND NEW ORING CHAIN, ITS AN 02' CR250-STOCK GEARIN IS 13/48- HOW MUCH OF A DIFF. IS THIS 49 GOINA BE? i KNOW ITS JUST ONE TOOTH DIFF. BUT JUST LOOKIN FOR SOME OPINIONS, THANKS GUYS.....

[psyklone393]

that will take just a little bit off of the top speed, and you'll find yourself shifting a little more frequently, but you'll probably like that gearing. i run 13/50 on smaller tight tracks and on the trails, but on the majority of the stuff i ride on now i run 13/49.

-Z

[MotoMan]

Good explaination Zack, and correct too.

Smokin66, I changed the title of your post to Sprockets instead of SPOCKETS for ya. Also, typing in all caps is considered YELLING on the internet and frankly dude, it's kinda annoying. Please turn your caps lock off.

[gumby_55]

I don't think you will notice much, or anything at all. I believe it takes 2.5 teeth in the back to equal one tooth on the countershaft sprocket. I would have just went one down in the front. The fronts are alot cheaper too.

[VET393]

Somewhere in the archives I posted a gearing chart for sprockets, Look in the knowledge based forums. I think the ratio is a bit more than 2.5 teeth, more like 3 or 4 teeth. Get to small on the front and the chain wears a little faster I think (IMO)

[mxerncolo]

...went down a tooth on the CS on CR125. Made a big difference. Now it feels like there's a pair of gerbils down there instead of just one. Top end was hurt a little bit, but no biggee - gets up there pretty quick tho'..
jim

[gumby_55]

Originally Posted by VET

Somewhere in the archives I posted a gearing chart for sprockets, Look in the knowledge based forums. I think the ratio is a bit more than 2.5 teeth, more like 3 or 4 teeth. Get to small on the front and the chain wears a little faster I think (IMO)

Hopefully somebody knows for sure, because I'm curious. It would be a nice thing to know.

[ossagp]

the amount of difference that the front does compared to the back depends on the two sizes you start with. If you really want to know, do some math for the combination you have and the one you are contemplating. It is pretty simple division. for instance, if you have a 13 tooth on the front and you have a 52 on the back you have a 4-1 ratio. if you have a 14 on the front and a 56 on the rear, you again have a 4-1 ratio. so in this case it works out to the front being equal to 4 teeth on the back. a 13 and a 49 will produce a different ratio and a different "value" of front vs back. (3.77 to 1).

[ossagp]

Oh,,,and if you feel one tooth on the back, you are really super sensitive or qualified to work for MotoCross action. They seem to think that is the magic number to add to everything that comes from the factory. think of it in percentages: If you add a tooth to a 50 tooth sprocket you are gearing down by 2%. that means on a 125 that run high in the rpms on a given lap you are turning 11,000 rpms to achieve the same speed that you used to get at only 10,800 rps...wow. look at it this way too,,,if your top speed used to be 60 it will now be 58.8. WHAT A DIFFERENCE!! see why I said it will qualify you to be a magazine sort? As your overall RPM drops so does the number,,,at 5000 rpms with a 13/50 you will be turning 100 rpms less than a 13/51. Think you can really feel that in the seat of your pants? Maybe if you have your head in the saddle so to speak, you would feel it more.

[nicster]

You can tell the difference, you just have to look at your tachometer. (ha Ha). Actually I just got some of those sidewinder sprockets for my YZ. I lowered my gearing trying to keep me from moving from first to second gear as much on some of the tight trails I ride. I can't stand catching neutral when I think I am in gear and almost falling on my face.

[psyklone393]

Originally Posted by ossagp

Oh,,,and if you feel one tooth on the back, you are really super sensitive or qualified to work for MotoCross action.

or you know how your bike feels. i can tell a difference on my bike, because i know how it feels. now put me on a bike i haven't ridden much and i doubt i'd notice one tooth in the rear.

-Z

[crdude]

im not sure about the gearing stuff, but im running sunstars on my bike and there pritty good as far as durability go JMO

[ossagp]

Psyk, maybe you do notice things that well. I have changed one tooth just because of what was available on two different occasions that i remember. Both times they were put on pro bikes of men who had made it into national mains, one at hangtown and one at washougal. I got no comment from either. if you know it has been done, and you are on a familiar bike, and on a familiar surface,,,you will find it. But few are able to find what amounts to a 100 rpm difference without knowing it is there. I am sure we all think we are the exception, but I dont believe it. The temp will actually affect the way your bike feels way more than one tooth will. (just get yours dyno'd at 65 degrees and then at 85 and see what I mean). But few notice it.

All in our heads? probably.

[souphmars]

i have a 51 tooth on the rear of my rm250, compared to the stock 48- i like it, the more bottom end is nice to me