A ? Of geometry in relation to trail...

[Chippertheripper]

In general, how does swingarm angle (and moving the wheel fore and aft at the same angle) and fork height (amount sticking above triples) affect trail?

I'm trying to get a few millimeters more, based on a recent conversation with pk.

[Degsy]

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Lower the rear or raise the front to get more trail. That's a VERY simple explanation.

[CBR929RE]

and by raise the front he means less fork sticking out above the top triple. when PK set my bike up at the last round he raised the rear as high as the shock could go and still needed a little more so he raised the front a little also.

[Alvecchio]

Is there a reason why you would do one rather than the other?

[Tunertype]

All kinds of fun stuff about bike geometry in this wiki about bike geometry.

http://en.wikipedia.org/wiki/Bicycle...geometry#Trail

The most likely reason for doing one over the other is that you start out with no adjustment in the front for increasing trail and can drop the forks a bit or chop them to get less trail. You can change your rake on your front fork by chopping the stem out and resetting it like chopper builders do.. Or more simply you can lower the rear swingarm. That also has limits as the tire will eventually contact the fender. Also increasing your front tire diameter can increase your trail with minimal effect on rake angle and rear suspension travel.

Increasing your trail usually increases straight line stability and reduces turning ability. Sport bikes often have links to bump up the rear to decrease trail and rake angle to get better turning.

[jwm2k3]

Is there a reason why you would do one rather than the other?

Rear is generally WAY easier

[Chippertheripper]

Rear is generally WAY easier

Not in my case.

I have no swingarm adjustability, and no ride height in the shock.

The reason for this was: I ride a dirtbike chassis designed for a 21" front wheel. Since I'm on 17's, the geometry is off a bit. By adjusting fork height and triple offset, i can get it back to "normal".

[gmdboston]

Not in my case.

I have no swingarm adjustability, and no ride height in the shock.

The reason for this was: I ride a dirtbike chassis designed for a 21" front wheel. Since I'm on 17's, the geometry is off a bit. By adjusting fork height and triple offset, i can get it back to "normal".

No you can't, you need triple clamps with a greatly reduced off set. I still can't find any one to make them a t reasonable cost for small quantities though.

[gmdboston]

Rear is generally WAY easier

Flawed thinking.

[Tricklidz]

If you're bored....
http://lidzduc.blogspot.com/search/label/GEOMETRY