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truing tires and gearing ???

truing tires and gearing ???

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Old 03-09-2007, 08:14 AM
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Default truing tires and gearing ???

if you would true your tire, will you go up or down a tooth on your pinion?
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Old 03-09-2007, 08:20 AM
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less tire = more teeth. You usally determine how many teeth by calculating the rollout (gearchart.com)
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Old 03-09-2007, 08:24 AM
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Possibly up, assuming you had the gearing right before you made the tire smaller. How much? Well its directly proportional to the change in tire diameter.

Say the tire was 58mm and you had the perfect gearing. Now you true them to 56mm. 58/56=1.0357

Say you were using a 28 tooth pinion. 28x1.0357=29 tooth pinion to keep the same rollout.
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Old 03-09-2007, 08:40 AM
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A good general rule is that for every mm your tire goes down in size, go up one tooth in pinion size.
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Old 03-09-2007, 08:44 AM
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For every 2mm of foam removed go up 1 tooth based on my rollout calculator, it's close but not exactly 2:1.
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Old 03-09-2007, 09:24 AM
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Originally Posted by A. Rhodes
A good general rule is that for every mm your tire goes down in size, go up one tooth in pinion size.
are you talking 64p or 48p?
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Old 03-09-2007, 09:37 AM
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Originally Posted by A. Rhodes
A good general rule is that for every mm your tire goes down in size, go up one tooth in pinion size.
That's way too much. See the above mathematical example. You'd have to take 2mm off a 58mm tire to need precisely a change from a 28 pinion to a 29.
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Old 03-09-2007, 10:08 AM
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Originally Posted by Kings Kid
are you talking 64p or 48p?
64P

Originally Posted by Iceracer
That's way too much. See the above mathematical example. You'd have to take 2mm off a 58mm tire to need precisely a change from a 28 pinion to a 29.
I said as a general rule, not as an exact to keep roll out perfect. I was given the 1 tooth per mm by two local racers at my track, but what do they know, they only TQ'd & won Snowbirds
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Old 03-09-2007, 10:17 AM
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Originally Posted by A. Rhodes
64P



I said as a general rule, not as an exact to keep roll out perfect. I was given the 1 tooth per mm by two local racers at my track, but what do they know, they only TQ'd & won Snowbirds
Well, if we take it to the extreme, and assume a 53mm tire being trued down to 52mm and start with a large pinion like a 38, we get closer to the rule of thumb working.

On the other hand, I'd much rather TQ Snowbirds than be some keyboard jockey with a calculator, so I defer to their greater experience!
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