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RSR - Ralf`s Selfmade Recumbent
Easy to see – this is not a normal Dutch Speed Bicycle (DSB), but my self-produced
recumbent using Parts from DSB. And this is the story how it came to it. Just to show what is
possible to do and encourage those who also want to try this. But look out: this is not an
exact construction guidance – this is my bicycle. And yours can look different. Variations in
parts that you use may cause variations in your construction. So: whatever you do you do it
at your own risk. And: neither I nor Dutch Speed Bicycles will be responsible for what you
do!
the idea
Why a recumbent? And why a selfmade one? My experiences with recumbents were
restricted to few testrides at expos and at dealers, but I was infected. My Bicycle should
perform this points:
-
-
-
-
-
an understeerer for easy arm-holding,
a 26-inch rear wheel for a mounting on a cycletrainer at the winter season,
a fullsuspension concept for comfortable riding even on worser roads,
somehow foldable for a transport in my car,
and not too expensive.
Now, hours for hours surfing in the internet wasn`t much help and so I finally stranded on
the homepage of Dutch Speed Bicycles, and the idea of a selfmade recumbent was born. My
Experience on that field? Nothing! Sure, I am a graduated engineer, but working in health
business. But with the help of my neighbour (and his blowpipe) it should be working. At the
beginning there was only a rough picture in my mind and don`t ask me of the hours I spent
with paper and pencil until I got an useful concept. After that I began with the selection of
the parts that I wanted to use and it started with this one:
the donor-frame
I thought: if I only need a rear
frame why not use only a rear
frame? Instead of cutting off an old
frame I used a rear triangle of a
cheap MTB-frame (an eBay-Auction
like several other parts on my
recumbent) with a so-called unified
rear
triangle,
that
means
the
bottom bracket is part of the rear
triangle.That was necessary because that got later the pivot point. After the disassembly the
only work to do was cutting off the supports of the original pivot point.
the connector-part
The DSB connector-part needed some changes to get fit for action on my frame. The
problem was the exact connection to the main
frame tube so that the rear triangle can be
switched under the main tube. For maximum
stability I chose this design: in the angled part
of the connector part I cut two slots for the
main frame tube, in the bottom part a bigger
cut makes place for the ‘seat tube’ of the rear
triangle.
the main frame
The
main
frame
comes
with
the
same
45*45*1,5mm rectangle steel tube like it is
used
on
the
original
DSB
frame.
The
connector-part is fitted in a 70°-angle on the
main tube. Extra care is necessary at this step
because the rear triangle must be in exact
rectangle to the main frame later on. After
welding it looks like this:
After fixing the pivot point it went on to the
next step. The sloping tube has to perform two
funktions: the support for the seat and for the
rear shock. For exact positioning you have to
consider that in unloaded condition there must
be enough room between the chain and the
edge of the connector-part (respectively the
nuts of the U-screws) for a proper function. The
rear shock support comes from that MTB-frame like the short circular tube too. The main
frame stands in a 15° angle to the ground. To achieve a 35° seat angle the seat tube has to
fit in a 50° angle to the main frame. The length of
the seat tube is given by the outline of the wooden
seat. Different to the DSB frame the seat isn`t
supported on its top end but it is stable enougt so
there will be no problem. The lower support for the
seat is also built from a piece of the rectangular
tube. The slots were needed for the possibility of
removing the seat.
After temporaryly mounting the seat and with the
help of the steerer I could fix the position of the
head tube exactly. This tube comes also from that
MTB-frame but was shortened slightly. For a
requested head tube angle of 70° the tube had to
fit in a 85°-angle to the main frame. Again exact working is necessary at this step to get an
perfect alignment on the complete recumbent later on.
The last working operation on the raw frame was creating the 10°-angle at the front end.
This one is necessary to lower the chain line thereby the chain gets not in contact with the
understeerer. Besides that the frame looks a little better.
the seat
The seat is cut in the same contour like
on
the
DSB,
but
fastening
In
order
is
to
somewhere
different.
remove the seat I use drive-in nuts in
the wood and rim screws from the
bottom side for fastening. Two pieces
of rubber are laid between seat and
frame and for the support of the front
nose of the seat I use a piece of wood
with adapted contour instead of the vibration isolator.
the understeerer
Maybe the most interesting chapter
because I could imagine to supply the
original DSB with an equal steerer.
(Probably you have to lower the upper
chain line with a chain roll and have to
lift the seat with some big washers or
so under the vibration isolator to give room for the
steerer). The general construction I looked upon
HPV`s Street Machine Gt. It consists of a 150mm
MTB-Ahead-stem (5° Flip-flop), a cromoly-steerer
without rise (approx. 550mm wide) and parts of an
old pair of bar-ends of that type you stick inside
the steerer for fastening, not clamp it on the
outside. Instead of the bented tubes of the bar-
ends I cut two tubes of a straight aluminium
steerer and equipped them with suitable holes. The stem is fitted that way that it shows
downwards, its end is then positioned tight upon the main frame. After that the complete
steerer has to be adjusted that it gets fully liberty of action until the grips are touching the
seat. The practicable steering angle is even big enough for narrow turns.
the complete recumbent
and so looks it like after all parts are mounted!
After painting with silver-grey hammered paint I could start with the assembly. Mounting of
the rear frame is like on the original DSB with U-bolts and self-locking nuts and I use the
original crankshaft bolts too. The aluminium parts of the crankshaft unit were not polished
but anodised. And the tube for the front derailleur is a piece of an alu seat tube with
28,6mm diameter.

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