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Adjusting the front boom
22
HP
Velotechnik
Adjusting the front boom to your leg
length
In order to adjust the leg length you have to
move the front boom (the front part of the
frame where the cranks are mounted) in the
main frame.
Loosen the clamping to adjust the length of the front boom.
Unscrew the bolts M8x35 under the main
tube with a 6 mm Allen key. Take a grip on
the front derailleur tube or both cranks and
move the front boom further into the frame
or pull it out while cautiously turning it.
Before pulling out the front boom, shift the
chain to the smallest chainring and sprocket.
Turn the cranks a little bit backwards while
pulling. Thus the chain is not under tension.
Attention!
After you have un-
screwed the clamping bolts take them off
and examine them for deformation. Lubri-
cate threads and heads thoroughly. Then
re-fit the bolts. If they don't turn easily you
will have to replace the bolts.
Adjust the front boom in a way that your leg
is fully extended when your heel (wearing flat
shoes) is in the foremost position on the
pedal. Experience shows that the pedal-to-
seat distance on a recumbent can be slightly
longer than on a conventional bicycle.
While you are pedalling, the ball of your foot
should be positioned above the centre of the
pedal axle.
It is important that your leg is not fully
straightened when the crank is in the fore-
most position. If the distance is too long it is
difficult to overcome this dead point, pedalling
becomes uncomfortable and there is too
much strain on the sinews of your feet and
legs. If the distance is too short you may
suffer from knee pain.
Adjust the front boom in a way that your knee will not be fully
straightened when pedalling.
Attention!
When you move the
front boom take care that its end does not
damage any light cables that possibly come
out of the main frame. Please inform your-
self about the length of the front boom on
your bicycle before you do any work.
While moving the front boom you also
have to move the light cables The light
cable must never be stressed by pulling.
For riders with short leg length the front
boom has to be cut by a bicycle mechanic, so
it can be inserted maximum possible. It is
important to trim the end of the tube neatly.
The bare metal of the shortened tube end has
to be protected against corrosion with a paint
stick or wax spray.
The maximum insertion of the front boom is
limited by possible heel cycle of the frame’s
cross bar, depending on the rider’s shoe size.
Please check before riding your bicycle that
there is enough heel clearance. For shorter
riders under 175 cm body height we recom-
mend to use shorter cranks.
Adjusting the front boom