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Gearing Question

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Would a 13/48 be a little shorter or taller than a 14/51? My brain cant quite get around this right now for some reason...

Anybody ride Star West in So Cal? What gearing do you run there? Im thinking the 14/48 is TOO tall so I want to try the 13/48 but dont want to be too short...

I guess Ill just have to try.

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If 14/48 is standard the going one down on the front is like going 4 up on the rear, I would try a 49 or 50 on the rear, I cant see you wanting any bigger on the rear. Hope that helps.

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14/48 is = to 3.43 (think of this as a muscle car with a 3.43 rear end)

14/51 is = to 3.64

13/48 is = to 3.69

Both of these would be 'shorter' or less top speed, but more torque per gear, with the gears closer together (again like a muscle car going to 4.11's in the rear).

Going up one tooth in the rear is equal to about a 2% change in ratio. The 14/51 is a 6.12% change from 3.43 (going up 3 teeth), the 13/48 is a 7.58% change.

I don't recommend going with a 13 tooth front sprocket. The chain has to make a tigher circle causing more wear, plus a larger front sprocket lessens the torque effect on the rear swing arm under full throttle conditions (less torque effect on the swing arm from the motor means the swing arm is more able to track the ground better). If you check out two-stroke Supercross bikes from a few years ago, they try to go bigger in the front, hence you'll see 53 & 54 teeth rear sprockets on the rear (this helps lessen the quick hit of the two-stroke and allows the rear end to work better). I did this with my 2001 RM250 and it tamed the rear end on full throttle out of corners.

Assuming you have a '06 RM-Z450 with its stock 14/48, I would say to start out no more than 2 teeth more on the rear. I have an '05 with 14/49 stock, and first went to a 50, then ended up with a 51. The 14/51 combo gets me going around tight MX corners in 2nd without having the fear of stalling it. My son stuck with the 50 tooth as he's faster in the corners than me. The 14/51 combo also made my 450 feel more like my '04 RM250 as far as rpm's in the corners and such. The 14/51 lets me get into 3rd quicker and torque out of corners with great traction too.

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Gregg, I just notice in your signature that you have an '05 RM-Z450. This should have come with a 49 as stock, yet your question said 48 stock (one of the changes to '06 was going from 14/49 to 14/48). Did you change to a 48? or are you assuming its a 48? If you aren't sure, just look on the side of the sprocket and it will state the number of teeth.

By the way, I haven't ridden at Star West, but my 14/51 on an '05 works well for Competition Park, Antelope Valley, Gorman, and Piru.

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The 06 has a 49 on the rear also. I read they were changing it in the early info, but my 06 has a 49. I went to a 50 rear and kept the stock 14 front.

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I was running a 47 in the desert but it obviously doesnt work for track riding, so I figured Id compromise and try a 48. Still ok in the desert (not really) and worked good for faster tracks, but now Im stuck.

Im thinking a 14/50 at the track and a 15/50 desert riding. A 13/50 for goat trail riding, be a little short but thats OK. I hate taking off the rear sprocket, draws blood almost every time. Are 15s available, I havent checked in a year.

I dont think this is even an issue with the four speed. You cant make a 5 speed MX bike right for all three of those conditions without a gear swap either can you?

Screw it...Im going riding! :thumbsup:

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I hate taking off the rear sprocket, draws blood almost every time.

Try kicking down the cresent wrench with your foot. Its much easier that way.

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Regarding a 15 tooth front sprocket, I briefly thought about this and looked at the current 14 tooth sprocket and the stock case saver. There is barely enough room between the chain and case saver with the 14 that I'm 95% sure the 15 won't fit (at least with the stock case saver).

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i ride star-west all the time. i put stock front and 50 tooth back. it will help your low end, snap off the bottom. still great for race town and glenn helen. but for desert no.

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i ride star-west all the time. i put stock front and 50 tooth back. it will help your low end, snap off the bottom. still great for race town and glenn helen. but for desert no.

The 14/48 was VERY BAD out there today. Im slow anyway, but it just needed to be lower to pop me over a couple of the doubles. The big double on the infield is beyond my abilities anyway...but I was struggling with a couple that I have done before when I was running lower gearing.

Im buying a 50 tooth. If I can get a 15 for it I can make a new case saver, it looks really tight to the swingarm too. Ill make it work...anything to avoid rear changes.

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Gregg,

It really sounds like you should just consider aquiring another rear wheel. Put the desert sprocket on it along with your chosen desert tire and be done with it. Yeah, it's $$, but in the long haul, I'm guessing it would save major headache.

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Gregg, I just notice in your signature that you have an '05 RM-Z450. This should have come with a 49 as stock, yet your question said 48 stock (one of the changes to '06 was going from 14/49 to 14/48). Did you change to a 48? or are you assuming its a 48? If you aren't sure, just look on the side of the sprocket and it will state the number of teeth.

By the way, I haven't ridden at Star West, but my 14/51 on an '05 works well for Competition Park, Antelope Valley, Gorman, and Piru.[/quote

My 05' Came with a 48 tooth stock, I beleive they went up to 49 for 06. I just put a 50 tooth on mine about a month ago, best move I've made. I ride Starwest/Racetown/Competetive Edge/Glen Helen and it works great on each.

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