56
b
c
d
a
9.3 Rear Shock.
Full suspension bicycles are equipped not only with a suspension fork
but also with movable rear stays which are sprung and damped by a
shock absorber
(a)
. This feature gives you better control of your bicycle
when riding cross-country or on rough road surfaces. It noticeably
reduces the strain on you and your bicycle caused by the mechanical
shocks from the terrain. With rear shocks this normally works with an air
spring element or, less frequently, with coil springs. Damping is usually
controlled by the use of oil. Depending on the system the rear shock has
one or more bearing axles with at least two bearings each.
For more information see the suspension glossary heading this
chapter.
9.3.1 Adjusting the Seating position.
Full suspension bicycles sag a little when you sit on the saddle. This
causes the saddle to tilt a little backwards, an effect which can be
compensated by adjusting the position of the saddle. If you have trouble
sitting, try lowering the nose of the saddle a little compared to your usual
position.
Full suspension bicycles have a greater ground clearance than
bicycles without rear suspension. With a properly adjusted
saddle height you will not be able to reach the floor with your
feet. Set the saddle a little lower to begin with
(b)
and practise
getting on and off the saddle.
9.3.2 Adjusting the Spring Rate.
In order to work optimally, the rear shock has to be adjusted to the
weight of the rider and the intended purpose. Be sure to have this
adjustment carried out by a BMW partner or a bicycle specialist shop of
your trust before delivery.
With an air spring element you have to inflate the rear shock before your
first ride
(c)
. The rear shock adjustment depends on the rider’s weight
and the sitting posture.
Please bear in mind that the rear swing arm of the rear shock should sag
a little under the rider’s weight. When the rear wheel passes through a
depression in the ground the spring can then extend and the suspension
mechanism will smooth out the uneven surface. If the selected air pres-
sure is too high, this effect is lost because the wheel will already be fully
extended. This means the loss of an important feature affecting both
safety and comfort.
To aid measurement you can use the rubber o-ring often available on the
shock’s shaft
(d)
, which slides further down the shaft as the rider gets
on the bicycle or slip a cable tie onto the thinner tube of the rear shock
so that it can still shift easily along the tube.
