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Old 03-17-2011, 03:42 AM   #1
tomgleeson
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Default Tire Question

This might sound stupid but I haven't been riding very long. I've been wondering why motorcycles have a smaller front tire than rear tire? I would have thought a larger front contact patch would be better due to the fact that people do most of their braking on the front tire.
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Old 03-17-2011, 04:36 AM   #2
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Some bikes have same front & rear. I find a large front wheel harder to manage at low speeds. Cruisers with light sheetmetal go with a taller skinny front wheel, bikes heavier in sheetmetal seem to go with a shorter wider front rubber. Sportbikes seem to put the widest rear that will fit for more ground coverqage (acceleration). I think it's mostly just styling preferences, but likely has mechanical benefits. I'm no engineer but woiuld assume a narrower tire would corner tighter, therefore a narrow front end would lead the bike through the corners better then a bike with same tires front & rear. There are several on here who know a lot more about this.
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Old 03-17-2011, 06:08 AM   #3
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Wheel-size is based on the estimated tire size (and empirical testing bears this out, generally). Each tire has a "job" to do - and the rear tire has more of a job keeping traction that the front (it propels the bike).

That said, in the name of "coolness", there are exaggerations away from "ideal": take the choppa' with the 21" skinny, raked and stretched way out in front, or the steamroller 230mm out back. Virtually unrideable, except from bar-to-bar.

The sport-bike world has their ridiculous examples as well.
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Old 03-17-2011, 07:15 AM   #4
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It is, of course, much more complicated than any of us want to get into.

For instance, the rear tends to be beefier in cross section because the traction demand for it is primarily to drive the bike forward.

The front has traction demands that include the majority of the braking effort, and turning the bike. So width is not the best answer.

And, the more front tire you have (or greater diameter), the more rotating mass that you have to fight every time you want to change direction (at road speeds).

It goes on and on...
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Old 03-17-2011, 07:39 AM   #5
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The front tire has to be smaller and lighter to make it easier to do mondo mono's, the rear tire has to be wider in case your Betty has some junk in her trunk.... na'ma'sayin?
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Old 03-18-2011, 03:40 AM   #6
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Steering, thats why!
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Old 03-18-2011, 07:19 AM   #7
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Quote:
Originally Posted by MOKE1K View Post
Steering, thats why!
Correct for $500, and you advance to the bonus round. The front tire needs quick turn-in, which is assisted by a narrower profile, and the rear needs a wider contact patch for grip during acceleration.

Tell Moke what else he's won, Johnny!
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Old 03-18-2011, 07:40 AM   #8
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Quote:
Originally Posted by Morbo the Destroyer View Post
Correct for $500, and you advance to the bonus round. The front tire needs quick turn-in, which is assisted by a narrower profile, and the rear needs a wider contact patch for grip during acceleration.

Tell Moke what else he's won, Johnny!

Morb, Moke has also won this dandy non-stick electric Wok from Westbend completed with a one year supply of Thai peanut oil, live kittens and red pepper oyster sauce.....That's right! Those tasty Asian dishes can now be made on your versatile new Westbend Wok in the comfort of your own home while you enjoy relaxing in front of your new wall-mounted 60 flat screen TV by Samsung.!!! (wild applause).....
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Old 03-18-2011, 10:03 PM   #9
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Quote:
Originally Posted by Morbo the Destroyer View Post
Tell Moke what else he's won, Johnny!
A BRAND NEW CAR................p.

You can put it in yout bathtub and fish for it, assuming you have a fishing pole, if not, try M80's.... or a bat.
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