How a motorcycle steers is decided largely by a handful of geometric measurements set when the frame is designed. Understanding them explains why a touring machine and a sportbike feel so different before either has moved.
What rake and trail describe
Rake is the angle of the steering head from vertical. Trail is the distance between where the steering axis would meet the ground and where the front tyre actually contacts it.
Trail is what makes a motorcycle self-centring. The contact patch sits behind the steering axis, so it is dragged into line the same way a shopping trolley castor straightens itself.
More trail means stronger self-centring, which means stability at speed and heavier effort to initiate a turn.
Why the two are tuned together
A steep steering head produces quick steering and a nervous machine. A shallow one produces the stability of a cruiser with long, slow responses.
Trail can be adjusted independently by offsetting the fork tubes from the steering axis, which lets a designer keep a given rake angle while changing how much the front wheel wants to straighten.
That independence is why two bikes with the same rake can require quite different effort at the handlebars.
What wheelbase controls
A long wheelbase resists changes in direction and resists the front wheel lifting under acceleration, which is why drag and touring machines are long.
A short wheelbase changes direction readily and makes the bike more willing to rotate, at the cost of being more easily upset by bumps and throttle inputs.
Swingarm length is the part of the wheelbase that also affects how the suspension reacts to drive forces, so it is rarely chosen for turning behaviour alone.
Why weight distribution changes everything else
Where the mass sits determines how much load each tyre carries, and a tyre generates grip roughly in proportion to the load on it.
A machine with more weight forward gives confident front-end feel in corners but is more prone to running wide under power.
Centre of gravity height matters as much as its position front to rear, because a higher mass transfers load more dramatically under braking and acceleration.
How riders change the numbers
Geometry is not entirely fixed. Raising or lowering the fork tubes in the yokes alters rake and trail, and adjusting rear ride height tilts the whole machine.
Adding a passenger or luggage shifts weight rearward and changes the loaded geometry, which is why manufacturers specify different suspension settings for a laden bike.
Tyre profile has a similar effect, since a more triangular section changes how quickly the contact patch moves as the machine leans and therefore how eagerly it drops into a turn.