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The DeltaWolf Under Seat Steering Mod
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Here is a simple modification for all you
DeltaWolf and
Marauder
builders who would like to try under seat steering. This mod is
based on some sketches I made, which I said I would upload for
others to try. Rather than give untested advice, I have
successfully made the modifications and will present them here
for all my fellow garage hackers and bike builders. Although
you will have to make a few cuts to your frame, the good news is
that you will not need to source any extra parts except for the
handlebars, and the surgery can be done in an afternoon. Under
seat steering allows the arms to rest in a more relaxed position
beside your body, and allows the pilot to climb in and out of
the bike without having the steering stem in the way. Under seat
steering does however feel quite different than the conventional
handle bars out front system, so think about this modification
and read it through before you start up your grinder. |
Photo 1 - Removing the original steering system.
*** All photos can be clicked for a larger view ***
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The original steering system must be completely removed from the
frame as shown in Photo 1. Before you cut any tubing, make an "X
marks the spot" mark on the main frame boom directly under the
original steering head tube as if you were looking through it
down to the frame. By transferring this mark to the frame, there
will be a good chance that the original steering control rod
will be the correct length after the surgery, saving you a bit
of work. Cut into the steering system tubing just above the
welds so you do not damage the original frame boom when you are
removing the original steering system. The leftover weld metal
can be carefully ground clean using a sanding disk to avoid
taking down any of the original frame tubing material. |
Photo 2 - Recycling the head tube.
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The head tube will be recycled, which makes since since you
already have all of the proper fitting steering parts such as
bearings, cups, and the fork stem. By making a few rough cuts
with a cut off disc as shown in Photo 2, you can safely liberate
the head tube from the frame tubing without the risk of damage.
Avoid cutting into the head tube material when you are
separating the parts, or you will have to repair the area later.
The head tube will be getting a few inches cut from it as well,
so don't worry about cleaning up the excess metal after
separation at this point. |
Photo 3 - Shortening the head tube.
| The head tube should be
cut down to a length of 2.75 inches, so there is minimal tubing
sticking up past the top and bottom of the main frame boom after
installation. This is done so the under seat steering system does
not interfere with the pilots legs, and keeps the ground clearance
to a reasonable level. If you tried to install a 6 inch tall head
tube through the frame, it would either come dangerously close to
the ground, or get in your way as you sat on the seat, so this
shortening surgery is necessary. As shown in Photo 3, mark off an
area around the head tube so you can cut it down to 2.75 inches in
length. If you have trouble marking a line all the way around the
head tube, use a piece of electrical tape as a guide by wrapping it
around the head tube to create a straight guide for cutting. After
you cut the head tube down to size, grind away any excess material
and then clean up the area so the tube is once again smooth. |
Photo 4 - Shortening the fork stem.
| Place the bearings and
cups back in the newly shortened head tube so you can install your
fork stem in order to determine how much it needs to be shortened.
You could also measure the piece that was removed from the head
tube, since all these parts once fit together perfectly. In Photo 4,
I have determined that I need to take out a 1.5 inch section of the
original steering fork stem in order to have it fit back into the
head tube. |
Photo 5 - Cutting the fork stem.
| The fork stem is shortened
by removing a part from the center of the tube, where there are no
threads. The best way to cut the tube, ensuring perfect alignment
later is by using a pipe cutter as shown in Photo 5. A pipe cutter
is an inexpensive hardware store tool that will come in very handy
for cutting all tubing sizes up to 1 inch in diameter. When you are
cone cutting the tube with a pipe cutter, the two halves will line
up perfectly, although with a little careful work, you can achieve
decent results with the grinder or a hacksaw as well. |
Photo 6 - Tack welded fork stem.
| The fork stem will be
rejoined once you remove the needed material, and if you have made a
perfect cut using a pipe cutter, the two halves should butt together
perfectly. A simple trick to ensure perfect alignment when tacking
the two parts together is by shoving in a gooseneck stem, which will
hold the two halves together perfectly. The two halves are then tack
welded in a few places around the perimeter as shown in Photo 6. If
using the gooseneck to help alignment, be sure not to weld through
the tubing or you will also weld the tubing to the gooseneck. |
Photo 7 - Fork stem surgery complete.
| Once you have the two fork
stem halves tack welded together so they are aligned perfectly,
remove the gooseneck or any other guide tubing then complete the
welding around the entire joint. make a solid weld, and don't worry
too much about how it looks at this point, since the welded area
will needed to be cleaned and ground a little bit in order to ensure
the bearing cubs can fit back over the tubing. Photo 7 shows the
completed weld after cleaning it up enough to get the bearing cups
to slide over the area. Only clean up the weld as much as necessary,
since you do not want to weaken this important joint. The completed
area should have a hill, not a valley. |
Photo 8 - Testing the steering hardware.
| Install all of the fork
hardware as shown in Photo 8, so you can make sure everything fits
together and spins around with minimal friction. Don't forget the
"balls into the cups" rule when inserting the fork bearings, or
there will seem to be excessive friction when you hand tighten the
hardware. The stem should move easily in the head tube. |
Photo 9 - Marking the head tube holes.
| The steering head tube
will be inserted through the frame so it is on the same angle as the
front head tube, just like it was in the original design. As we
discussed in the original DeltaWolf design, the control arms and
head tubes should all be at the same angle so there is no rubbing
between the control arms and the ball joints. To mark the frame
where the head tube will go, trace a circle over the original mark
you made using a marker on the inside of the leftover head tube
stub. You can then transfer a line at the same angle as the front
head tube down the frame to make the hole on the other side. Photo 9
shows the frame marked for the head tube insertion. In other words,
the under seat steering head tube should be inserted through the
frame so it is sitting at the same angle as the front head tube when
you are done. |
Photo 10 - The can opener method.
| Chances are, you do not
have a drill bit even close to the size needed to cut the hole in
the frame boom for the head tube, so the "can opener" method shown
in Photo 10 can be used. Center punch a bunch of holes around the
area marked and then drill a bunch of smaller holes in order to pop
the "lid" out of the hole like a can opener would open a tin can. I
have used this method many times to make huge holes, since my hand
drill only holds a 3/4 maximum size inch drill bit. Yes, you will
need to clean up the area with a round file, but this is unavoidable
anyhow, since the hole will have to be slightly oblong to take the
head tube at an angle anyhow. This drilling and hand filing takes
less than an hour to complete both sides. |
Photo 11 - Head tube hole completed.
| After an hour if filing
with a hand held round file, I had the head tube fitting perfectly
through the holes in the main frame boom as shown in Photo 11. If I
stood back a and looked at both head tubes, they were very close to
the same angle, which was the original goal. A few degrees either
way is not going to be a real problem, but it would be difficult to
align the ball joint hardware if this new head tube were inserted
straight through the frame at 90 degrees. When using the round file,
it is easy to file away both side of the frame at the same time, so
you can keep the gap to a minimum for a better weld. |
Photo 12 - Head tube welded to the frame.
| Once you have the head
tube fitting snuggly through the main frame boom, weld it in place
using a small weld bead as shown in Photo 12. When I say small weld
bead, I mean you should try to keep the heat down as much as you
can, only using enough weld metal in order to fill the gaps. You
should also work around the joint by switching sides after an inch
of weld bead so you keep heat distortion to a minimum. The welding
shown in Photo 12 did not cause any noticeable distortion to the
main frame boom when completed. Also, do not install the bearing
cups while you weld, or you may damage them accidentally. |
Photo 13 - Testing the control arm length.
| If all went well, there is
a good change the original control rod will be the correct length,
or so close that is does not need any adjustment, which is why the
line was transferred to the frame from the original head tube before
it was removed. If your control rod hardware is threaded and
adjustable, then you do not have to worry about this, but because
mine was not, it was nice not to have to cut and reweld the rod.
Photo 13 shows the steering hardware reinstalled exactly the way it
was in the original design, allowing plenty of steering angle in
both directions. |
Photo 14 - Gooseneck shortening surgery.
| The surgery is almost
complete! Now that your handlebars will be held from the underside
of the steering boom, a gooseneck must be installed so that is faces
the ground. Obviously, an 8 inch long gooseneck is not going to work
because it will seriously compromise your ground clearance, creating
a dangerous "hook" under your trike that could become an issue every
time you rolled over a speed bump or curb. By cutting down a
standard gooseneck as shown in Photo 14, the resulting ground
clearance is no different that before, with the guide pulley being
the lowest object under the bike. To shorten the gooseneck, I just
cut out a section (shown above the bolt) at the same angle as the
original end so that the wedge shaped bolt would still work
properly. I then cut and rewelded the original bolt so it was the
correct length. I would recommend you simply purchase a new bolt
unless you are extremely confident with your welding. |
Photo 15 - Testing possible handle bars.
| The handlebars that you
choose should allow you a full range of steering motion, not
interfere with your body when pedaling, offer room to mount the
levers and shifters, and just be all around comfortable. As shown in
Photo 15, I found these big old "ape hangers" from a chopper style
bike that fit perfectly. You may have to hunt around for the perfect
handlebars or simply fashion your own by bending up some 3/4 thin
walled conduit. The best way to approach finding a set of handlebars
is to first decide where you want to hang on rather than using bars
that force you to some uncomfortable position. Also shown in Photo
15 are the little bits and pieces that were removed due to the
surgery. |
Photo 15 - Adding the cables.
| Once the handlebars are
functioning properly, it's time to touch up the battle scared frame
and add all those shifter and brake cables back where they belong.
Since the handle grip area is now a little lower on the bike, the
cables will not have to travel as far so you will not have to
install longer cables. The extra two or three inches of cable slack
can easily be taken up by a little creative cable routing and some
zip ties here and there. As usual, make sure no cable is allowed to
rub on any moving part of the bike and that the steering can make a
full range of motion without putting any of the cables under extreme
tension. A cable should not be forced around a sharp corner, so make
all your bends at least as large as the curve of the large chain
ring to be safe. As for the chain, the drive side goes above the
handle bars and the return side is below the handlebars - this
leaves adequate clearance so there is no chain rubbing on the
handlebar tubing. |
Photo 15 - Ready for the street!
So there you have it, the
under seat steering modification is now complete, and my DeltaWolf
is ready to hit the streets at speeds that would make most trikes
cry. I must admit, the first test ride felt a bit faster with the
new steering system, but that may just be due to the fact that I
have been eagerly awaiting the return of my DeltaWolf. The turning
circle is still extremely tight, and the new relaxed handlebar
position felt very comfortable. I am giving this modification a two
thumbs up, and must say that it was well worth the effort. I like
both steering systems an equal amount, but this new under seat
steering system will allow easy access to the pilot's seat if I were
to add a full streamlined fairing later on. Maybe that will be the
next DeltaWolf modification, we will see.
Thanks again for all your support - hope to see your completed rides
in the gallery!
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