BMW K 1300 GT User Manual

Page 22

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BMW

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Information

10/2008

Page 22

Prior to the launch of the K 1200 S in 2004 the Telelever was the only
front-wheel suspension system able to achieve genuine success in the market
next to the telescopic fork still playing a dominating role at the time. And this
is no surprise, considering that the Telelever offers superior functions and
comfort features and is the optimum solution for BMW’s range of Boxer
motorcycles.

The K 1300 S, like its predecessor, now offers an even better solution for
a sports motorcycle with perfect kinematics – the Duolever. In this case
a square confi guration of arms made up of two almost parallel longitudinal
struts able to swivel within the frame support the wheel bearing and allow the
wheel to move up and down in a steady stroke wherever required.

The wheel bearing newly fi nished for the K 1300 S as an extra-light and
high-strength aluminium alloy casting is connected to the longitudinal arms
by two ball joints and is therefore able to perform an appropriate steering
function.

The steering axis is the straight line between the two ball joints, steering
movements being transmitted and the entire system being separated from the
wheel moving up and down by a scissor-like bar assembly. The handlebar,
fi nally, rests in conventional confi guration in the frame head turning as desired
in the appropriate direction.

A central spring strut pivoting on the lower longitudinal arm provides the
spring and damping action required to give the K 1300 S an even fi rmer
set-up for enhanced feedback to the rider. The geometry of the two
longitudinal arms allows the wheels to perform virtually ideal movements,
as required in a given situation. The wheel is able to move up and down
on account of the kinematic confi guration of the overall system in an almost
straight trajectory minimising any change in castor and wheelbase as a
function of spring travel.

The wheel movement curve is slightly inclined to the rear allowing the wheel
to follow bumps on the road in a natural motion in the inbound and rebound
process, avoiding and setting off the impact of bumps on the road surface.

In combination with the low-friction rotational movement of the longitudinal
arms, spring action thus always remains smooth and supple even under high
lateral forces or impacts. This allowed the engineers at BMW Motorrad to
choose a fi rm set-up without making any noticeable concessions in terms
of riding comfort, thus achieving the optimum result for a sports motorcycle.
And with wheel forces resting on the longitudinal arm positioned far down

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