13 tooth front?

[Good]

What do you guys think of a 13 tooth front sprocket for the dunes with a 48 rear?  I tried to search, but am not literate at such things...

I chewed all the teeth of my current on and am going to pick up another 14, but am thinking about getting a 13 to go with it.  Too much?

[Hillclimb#42]

 What are you running on the back? There are some gear ratio charts on here somewhere. The front and back work together for a ratio. Also, 13 is gearing down from a 14, and probably not needed for sand riding. Something else that comes to mind is that you will most likely need to shorten your chain to run a 13.
 I personally ride 13-47, or sometimes 13-49 for the trick riding. I use alot of second and third. I could gear taller then ride alot more 1st and 2nd. I think one tooth gained on the front is equal to losing three on the back. There is better range of adjustments from the back then obviously, and sometimes a tweak is better than a over haul.

[FuriouSly]

Here is the link to the gearin chart;

http://www.kxriders.com/forums/index.php?page=12

3.00:1 is overall faster top end speed than 4.00:1

3.36:1 ratio (stock 14/47) gearing is more top end speed and less quick off the line.  Good overal gearing for most conditions.

3.54:1 ratio (13/46) gearing means more bottom end quickness than stock with loss of overall top end speed.  The smaller rear sprocket does not work as well in sand conditions since a larger sprocket will transfer the power better to a larger diameter paddle tire.

3.57:1 ratio (14/50) is lower gearing so less top speed yet more quick off the line.  Another benefit of running a larger gear in the back is better torque usage to the rear wheel and ultimately to the ground.

I personally run a 14/50 (3.57:1) at the dunes.  Gears close enough that you can start drag races in 2nd gear and finish pulling hills in 4th.  Still gives you great top-end speed with 5th gear.  I don't commonly run 5th (30% of the time) at the dunes since that gear is mostly flats or large distance, but when you need it...  its there and into overdrive you go.

13 is a pretty small low end sprocket, mostly for very fast starts with less top-end.  Also used in tight slow speed woods/trails.

Of course this is just my own opinion on the subject and I have no real mechanical or engneering degree in this area....   

Sly

[Good]

Thanx for the link!  I couldn't find it, though I knew it was here somewhere.  I run the 48 rear and I was just wondering if the 13 front would be bad for the dunes to match it.  I don't know if the 3.69:1 ratio is too much...  I'm thinking I might go back to a 47 and run the 14 for desert and 13 for dunes.  Just trying to keep it simple, and with more power than stock, the 47 might be OK.

[Good]

Or maybe run the 15/14 fronts with a 51 rear...  What about the 16/15 with a 54 tooth rear?  Why don't guys run these combos?  That 16/15 combo has a smaller variation in ratio than the others, and that's a HUGE rear for that drive gear power transfer to tire thing FuriouSly mentioned earlier.  How much variation in chain would these be?  Is there a chart for lengthening your chain?

[Hillclimb#42]

 I run a 13, because like Furiously pointed out I need the quick take off, and the tight trails here. I ride sand though and a 14 is much better, in my opinion. Maybe even 15. Soft sand eats the power. Here, we hit the Badlands (Sand Park) after a good rain, for some real hook-up and 15 would be a little tall. Furiously has another good point, that the tire on your bike plays a part. A paddle tire on sand or new nobbies on dirt might make you want to gear down. I say to make it simple, run as tall of a gear ratio as possible with no bogging under your normal riding style. But hey I'm also no engineer, but it looks like Furiously is closer.  

[FuriouSly]

Good;
   A 13, 14, and 15 are the most common front sprockets on just about everything dirt, whether a bike or quad.  A 12 and 16 are very rare.  So stay whithin those parameters.

   45 to 51 are the most common rear sprockets for dirt bikes.  Motards and street can run smaller for more top end.

So, like HC#42 said, you need to change your gearing based on what you ride and where.

I would suggest 14/50 for sand.

As far as chains go, usually one tooth on the front like in 13/50 and 14/50 can be adjusted for in the same chain without too much rear wheelbase change.  Same goes for 14/50 and 14/47 but moves the rear wheel much farther front to back changing the wheelbase more.  Now 13/47 to 14/50 would more than likely not work with the same chain.

Why worry about wheelbase?  Well,  in the trails a middle to more forward placement of the rear axle in the swingarm will give you a more reactive and nimble steering action since the wheelbase in shorter. But watch out for the wheelies 

For drags and racing in the sand where a paddle gives the ultimate in hook-up, moving the axle as far back on the swingarm (or using a longer swingarm) will give better nose down input since the wheelbase is longer.  But the already weak steering finese of the KX500 suffers for it.  Also, depending on how big the paddles are (overall diameter) and the rim (size 18,19) the best is to move the rear wheel all the way back as far as possible.  Then plan on having a seperate chain/sprocket set for your other riding styles.

Tire Size?  The Kings Turbo 8 scoop sand paddle that I use comes in 18" and 19" sizes.  The overall diameter of the 18" is 28" (CR500) and the overall diameter of the 19" is 28 1/2" (KX500).  The CR500 has a shorter swingarm with less room so the rear tire has to be set as far back on the swingarm or the paddle hit it.

Less brains than experience talkin' ...   
Sly

[moreccsthanlbs]

i keep a 45 tooth on the rear, and swap between 13,14, and 15 counter. i pretty much run a 15/45 combo. when i go to glamis or dumont, i'll drop down to a 13. i also run a 10 paddle skat-trak