6
9.6 Rim brakes (U-brakes)
Many BMX bikes are equipped with a rotor
and in connection with this system with
brakes, also referred to as U-brakes. Com-
mon U-brake designs have two brake arms
mounted separately on either side of the rim.
When pulling the brake lever, both arms are
contracted by the cable, the pads touch the
rim.
The brake pads should hit the rim simulta-
neously, both first touching it with the front
portion of their surface. At the moment of
the first contact, their rear part should be a
millimetre away from the rim. Viewed from
the top, the brake pads form a “V” with the
trough pointing to the front. This V-shaped
setting prevents screeching when the brakes
are applied. To align the brake pads, release
the fixing bolts, re-align the pads and re-
tighten the fixing bolt.
The brake lever must always remain clear of
the handlebars. You should not be able to
pull it all the way to the handlebars even in
the event of an emergency stop. A correctly
adjusted brake will pass on all these points.
Adjusting the position of the brake
pads to the rims requires a consider-
able degree of skill. Replacing and adjust-
ing the brake pads is a job best left to your
MERIDA dealer.
The brake cable of U-brakes with rotor system
is composed of several sections all of which
must be checked and adjusted. To begin
with, release the counter nut of all adjusting
devices; then unscrew the adjusting bolt until
the cable tension meets your requirements.
Finish by holding the bolt, while tightening
the counter nut against the limit stop. The
brake only works properly, when all sections
are adjusted accurately – a job for a skilled
mechanic.
9. The brake system
9.6. Checking, adjusting and
synchronizing U-brakes
Check whether the brake pads are accurately
aligned with the rims and still sufficiently thick.
You can judge the wear of the brake pads by
appearance of the grooves. If the pads are
worn down to the bottom of the grooves, it is
time to replace them.
