Front Sprocket/Rear tire Question

[Toadz400]

I am currently running a 14/38 with 18" rear tires set-up. My chain is getting pretty bad and the teeth are wearing down on the sprockets, time for an upgrade.

With the 14t and 18" tires I have insane low end, but absolutely no top end.

I loved my power when I had the 14t and 20" tires, so would it make sense to move back up to a 15t with the 18" tires?

I will probably end up buying a 14t and 15t sprocket just incase one is better than the other, but I just wanted to hear some people's opinions before I went ahead with my order.

Also, who sells those gold x-chains?

[Florida400EX]

c&d has a bunch of DID xring chains in stock, I'm sure they're loaded with sprockets too, give them a ring, countersprockets are ussualy only like $20 a peice, so you can get a 14T and a 15T.

[wilkin250r]

You would be surprised to find the change that tire diameter will make.

There is a little more to it than just gear ratio. Overall weight and rotational inertia play an important part, but let's just ignore them for now, and concentrate strictly on gearing.

I won't bore you with all the details, but you can calculate the tire diameter, sprocket sizes and final drive ratio of the different setups. Changing the tire size from the stock 20 inch down to 18 inch, the gearing to get back to stock ratio is right between 16/36 and 16/37. That's huge. So going to a 15/38 on 18 inch tires, you're still much lower than the stock drive ratio, so you'll still have better acceleration than stock.

[WOracing]

what about on the 450r....

im running 18" tires with stock gearing and off hand i dont know what it is but i dont wanna mess with it until i actually ride it...just need to know what would get me back to stock gearing (or close) with 18" tires

[wilkin250r]

I'm not sure. It would depend on the stock gearing, I suppose. If the 450r comes stock 15/38 with 20 inch tires, then it would be the same 16/36 or 16/37 with 18 inch tires to get back to stock gearing.

[Toadz400]

Originally posted by wilkin250r
You would be surprised to find the change that tire diameter will make.

There is a little more to it than just gear ratio. Overall weight and rotational inertia play an important part, but let's just ignore them for now, and concentrate strictly on gearing.

I won't bore you with all the details, but you can calculate the tire diameter, sprocket sizes and final drive ratio of the different setups. Changing the tire size from the stock 20 inch down to 18 inch, the gearing to get back to stock ratio is right between 16/36 and 16/37. That's huge. So going to a 15/38 on 18 inch tires, you're still much lower than the stock drive ratio, so you'll still have better acceleration than stock.

I know that the smaller tires makes a huge difference in the final drive ratio, I am just thinking maybe I should go back to stock gearing (and still have awesome low end with the 18" tires) because I think I have a little TOO much low end power.

Could you explain the weight and rotational inertia for me:D ?

[fastkid400]

I got my DID X-ring from Rocky Mountain, cheap sprokets too

about the inertia, taller and heavier tires are more weight, and the less rotating mass, the less it takes to turn them, so if u got light rims and tires, u will have more acceleration. wheew :blah:

[Toadz400]

Originally posted by fastkid400
I got my DID X-ring from Rocky Mountain, cheap sprokets too

about the inertia, taller and heavier tires are more weight, and the less rotating mass, the less it takes to turn them, so if u got light rims and tires, u will have more acceleration. wheew :blah:

Ah, so I bet my HiPers really help huh?:D