Gear system and chain
52
Danger!
Take care that the chain
tubes keep at least a 5 cm distance to the
rear and front derailleur when the chain is
stretched to the maximum, and that the
tubes are well fastened. If necessary you
will have to shorten the tubes. If the end of
a chain tube gets into the rotating parts of
the drive train the drive train can be
blocked and the chain tubes may be de-
stroyed.
Danger!
The rear ends of the
upper chain tube have to be secured
against moving with a tight rubber tube
over the retention spring. Without the
rubber tube the chain tube may be dragged
forward into the turning chain roller or
chainring and thus be damaged by the
chain.
Danger!
Check the chain tubes
frequently if they are damaged or defective.
Replace defective chain tubes immediately.
If the chain tubes are worn in the area of
the retention spring or tube mountings,
the chain will touch the retention spring,
leading to failure of the spring and mount-
ings. As a result, the chain tube can get
into the drive train and block it!
Expanding the tube ends
The ends of the tubes are expanded like a
trumpet so that the chain can enter smoothly
without friction and without making noises.
When the ends are worn out you can renew
them by expanding them again. Remove the
chain by opening the power link or open it
with a special chain riveting tool. Cut the
worn part of the tube exactly perpendicular
with a sharp knife.
Heat the last 5 – 10 mm at the end of the
tube with a gas burner, a hot air gun, or a
candle and turn it permanently until the col-
our of the utmost edge turns from a dull black
to a shiny black. Now you expand the end
with a proper tool, e.g. the rounded grip of a
screwdriver. Quench the expanded end im-
mediately with cold water. Take care that the
tubes don't catch fire. At any rate work in a
place with sufficient ventilation.
If the tube is too short after you have cut it so
that there is not enough protection anymore
it has to be replaced. You can buy spare tubes
either as uncut tubes or already cut into the
correct length, complete with retention spring
from your specialist dealer.
Replacing the tubes
In order to exchange single parts in the upper
chain tubes cut the old tube at the retention
spring at the chain roller and pull the remain-
ing part off the spring. Now move the smooth
part of the new tube through the spring and
rubber tube, then expand the tube end as de-
scribed above.
Changing the complete upper chain protec-
tion or the retention spring
Remove the bolt in the chain roller with an
Allen key 6 mm. Take off the chain roller, the
washer and the chain retention hook.
The end of the threaded tube in the frame is
protected with a plastic tube. Take the reten-
tion spring off this plastic tube and put on the
new retention spring. Turn the spring so that
the retention springs run under the spacer to
the tubes and the wires lie between frame and
chain tube; that way the spirals face outwards.
