Sprockets

[Athelite]

When does it make more sense to change the front sprocket vs the rear one?

[TwoCrfs]

I Run 1 Bigger On The Front And 3 Up On The Rear For Stock Gearing. "Rumor Has It" Running A Bigger Countershaft Is A Little Easier On The Tranny.

I Always Run 1 Up On The Front And Only Change My Rear Sprocket. I Have Sprockets From 48-53 FOr Gearing Changes.

[WILDMAN442]

If both are showing signs of wear, replace both of them.

If you do only one, it is possible to wear them Unevenly.

Justin

[Wild Alaskan]

the load per tooth is about 3 times higher on the front, so it wears faster

[tribalbc]

the load per tooth is about 3 times higher on the front, so it wears faster

Exactly. I go through 2 countershafts for every rear. Makes your rear sprocket and chain last longer if you replace the counter when you start to see wear.

[Athelite]

I Run 1 Bigger On The Front And 3 Up On The Rear For Stock Gearing. "Rumor Has It" Running A Bigger Countershaft Is A Little Easier On The Tranny.

I Always Run 1 Up On The Front And Only Change My Rear Sprocket. I Have Sprockets From 48-53 FOr Gearing Changes.

I would have thought a smaller front sprocket would be easier in terms of torque, but would require higher rpm for the same speed at the rear wheel. Have I got this backwards?

[Athelite]

Oh, and I guess I could have been clearer; I was really referring more to the performance aspect and not so much in terms of wear, though the insights are appreciated.

[Jakeblues]

Take a set eng rpm:

larger front will equal more speed, smaller front will equal slower speed

larger rear will equal slower speed, smaller rear will equal higher speed

One tooth difference on the front will be close to a three tooth difference on the rear.

Example: stock combo 14/49

looking for more top speed

15 front and a 46 rear would give the same results when changed individually.

When using gearing changes to get more speed or acceleration you trade one for the other.

The truth of the "rumor" is a larger front sprocket is easier on the chain, the link pins wear less because the links do not have to move as much as they would wrapping around a smaller circumference.

here is a good chart for sprocket combo gear ratios:

http://www.jtsprockets.com/fileadmin/files/jtgearratio.pdf

[Still Bill]

Adding 3 or 4 teeth to the rear will require a longer chain, or moving the rear wheel forward significantly, which can affect handling.

Subtracting 1 from (or adding 1 to) the front can give the same gearing effect as above, but you can still use the same chain, and not have to move the rear wheel as much.

[stlavsa]

Exactly. I go through 2 countershafts for every rear. Makes your rear sprocket and chain last longer if you replace the counter when you start to see wear.

If your using an aluminum rear sprocket ie renthal ultralite, its gonna wear faster than the steel countersprocket.

I think its pretty common to run an aluminum rear coupled with a steel counter.

[Burnrider]

Just a side note to add:

For the bigger bikes, a 13T front seems to tear up the chain and itself quicker than a 14T sprocket. 13/52 combo runs 2000 miles for my 450 EXC, 14/52 will run 3000 miles easy. If you have the option to go 14T on bikes over 350 cc's , could be worth it.

[Athelite]

So I presume since it seems 13-15 is pretty much the most common counter, and 47 - 54 are the most common rears, that since (except for at the extremes) almost all of the ratios can be achieved that the decision to switch the front or the rear is based on what's on sale?

Some consideration for chain life means as large a front sprocket as you can with the chain and then switch the rear for more torque or more top-end. About right?