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Geometry Basics 101
Geometry Basics
Ahhh, geometry is complicated.
So many things have a direct effect.
Basics:
As stated by others already as the rear of the bike is raised you lose trail.
As you raise the front of the bike you gain trail.
Trail is the built in stability of the bike.
You want as little trail as possible, but you MUST have enought to insure both stability and the ability to STEER.
As you remove trail the bike no longer want to go straight, it wants to fall over or turn.
This is what happens entering a turn, the less trail the lighter and faster you can change direction.
But as you exit the turn, you are already leaned over and now are applying power.
Now you need to be able to hold your line, tighten your line or loosen your line, I call this the ability to STEER.
The two, turning and steering, are different.
If you do not have enought trail, as you exit a turn and apply power, your bike will push to the outside and the only way to stop it is to back off the throttle.
Other things that effect turning and steering, tire shape and construction. Weight and where the weight on the bike is.
Wheelbase lenght.
Handlebar lenght and angle (leverage).
Footpeg lenght and location (leverage).
Suspension.
Gearing, especially on a 1098 as you change ride height as you adjust the chain tension.
Just some notes:
As pointed out already when you change the Triple Tree offset, (the Ohlins guys hate when I say that they call them Triple Clamps), from say 36MM to 30 MM you are increasing trail, adding stability, making it harder to "turn in". But you are also reducing the wheelbase by that same 6MM, that is a lot!! On conventional swingarms you can usually add some wheelbase lenght back in, but iot is not so easy on a single eccentric single sided swingarm.
More stuff: all these numbers are appox.
a 1 degree RAKE change is about a 6MM change in trail
a 4MM rear ride height change (measured at the rear axle) is about a 1 MM trail change
a 4MM front ride height change is about a 1 MM trail change.
a 1mm offset change is a 1mm trail change and a 1mm wheelbase change.
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