HP Velotechnik trikes - Manual (Page 57)

Gear system and chain
53
Handling instructions
Caution! 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 neces-
sary you will have to shorten the tubes. If
the end of a chain tube gets into the rotat-
ing parts of the drive train the drive train
can be blocked and the chain tubes may be
destroyed.
Caution! 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.
Caution! 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 colour 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 immediately with
cold water.
Take care that the tubes don't catch fire. At
any rate work in a place with sufficient ventila-
tion. 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 re-
tention 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 retention 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 be-
tween frame and chain tube; that way the spi-
rals face outwards.