Best sprocket combo for tire size differance

[lilhubb9]

Ok so I know this horse has been ridden hard but I searched and didnt get the exact answer I was looking for. Long story short I went from 20s to 18s in the rear. I still have the stock 14-42 setup and Im going on a trip to the dunes and want a little more legs on the top end. My question is what sprocket size would I need to get for the front to give me about the same gearing as the stock 20' tire 14-42 setup with the 18s?

[hcomras]

U need to lower the rear. Try a 40 tooth and see ho u like it. Remember ull need a new chain too tho. The stock chain has no master link.

[cccutter]

yeah 40 tooth or 38. the lower the rear teeth, the more top speed and less acceleration.

[08x]

If you want to get technical and do the math, a 14/38 combo with 18s would be the closest to 14/42 with 20s. With 14/42, for every one revolution of the front sprocket, the 20 inch rear tires will travel roughly 20.94 inches forward. With 14/38, for every revolution of the front sprocket, the 18 inch rear tires will travel roughly 20.83 inches forward.

Remember that when you change gearing, you are changing your top end and acceleration, but you are also changing your shift "points", because it is affecting all 5 of your gears, not just 5th for the top end. So you may not like the "feel" of a certain combo because it may throw off your shifting a bit from what your used to. Just something to keep in mind.

I guess what I am try to say is that while 14/38 looks the best on paper, it may not be what you like the best, you will just have to try. FYI, the Xmx comes stock with 14/39, which would travel the wheels 20.30 inches for every rev. Going to 15/42 would travel the wheels 20.20 inches per rev.

[lilhubb9]

Thanks for the info, any idea where to locate a 38t? Having trouble actually locating one, and what size chain would I need?

[08x]

Try Motoworks for the sprockets. They might have a 38. You would have to give them a call to find out for sure. The chain is a 520. I would get an o-ring chain, unless your racing and going to be putting a new one on frequently. I wasn't sure how many links to get when I got a new one for my 13/39 sprockets, so I got 100 links, but ended up cutting a couple off. Its always easier to get it longer and take a few out if you need to.

[gregory]

You can use you chaine if you want you just need a master link set , we sell them for $5 at our shop. But if your chain is worn just replace