W6SDO.COM                                                 SAN DIEGO, CALIFORNIA USA    
After completing the installation of a number of antennas on
my small city lot, which now provide coverage of all of the
ham bands from 160 meters to 440 MHz, I was looking for my
next project. Since I ride my bicycle three or four times a
week on a year round basis and ride almost 2,000 miles a
year, it occurred to me that a bicycle mobile would be an
interesting and fun project. The only guidelines for the
project were that it should have a power output of 100 watts,
should be as light as possible and sport the most efficient
antenna that is practical on a bicycle.
For my first try at a bicycle mobile, I strapped my
trusty Kenwood TS-590S transceiver onto the
carrier on the back of my bike, loaded five pounds
of lithium polymer batteries into the tool bag,
bolted the mast of a half wave 17 meter horizontal
dipole (supported by a 12 foot long telescoping
“painters pole”) to the frame of the bike with a
couple U-bolts and headed for the Pacific Ocean
beaches that are only a few miles west of my
QTH. I was extremely encouraged by the results
from this first outing after working Honolulu as my
very first contact followed by a lighthouse off the
coast of Alabama, a VE4 and a half dozen other
stations across the states. This has possibilities,
I thought.

So I started seriously planning out what a first
class bicycle mobile might look like.





The final bicycle mobile, designed around an
ICOM 7000 transceiver, has now been completed
and I have made well over 100 contacts using
this mobile. This bicycle mobile has met all of my
expectations. The finished bicycle mobile is
pictured below.





















The setup is light (8 lb 2 oz lighter than with the
Kenwood TS-590S that I used for my first bicycle
mobile), is compact and is powerful. It has a radio
control panel that is designed to be separated
from the main part of the transceiver so that it
can be remotely  location on the bicycle handle
bars in front of the rider. This provides easy
viewing, tuning and adjustment while riding. This
control setup including a note pad and
push-to-talk button are pictured below.






















The two bicycle handlebar mounts that I used to
secure the controller’s mounting panel are very
sturdy and were purchased on Amazon at a cost
of about $9.00 each.

I have also mounted an additional mount onto the
handlebars that carries a small writing pad and a
pencil (that hangs on a string from the handle
bars). I use this pad to jot down the call letters,
names and times of contacts so that I can enter
them later into the log at home. A closeup of the
attachment brackets used for this setup is
pictured below.



















The acquisition of the ICOM 7000 has also
provided me with a very high quality mobile rig for
my Roadtrek camper van since the unit can be
very easily removed from the bike and installed
into the van in just a few minutes. The only
additional cost for this dual roll is the cost of am
additional remote kit which includes the controller
interconnecting cable plus the controller and
main unit mounting brackets. This kit costs less
than $100.

A further benefit of the ICOM 7000 when it is
powered from lithium polymer batteries is that the
rig stops operating when the battery voltage
drops below about 10 volts. This is an important
benefit for bicycle mobile operation since the
lithium polymer battery that I am using can be
permanently damaged if they are discharged
much below 9.0 volts. While lead acid or other
batteries could be used in place of the lithium
polymer batteries, they will generally weigh about
twice as much as the lithium polymer units for the
same storage capacity. This change would add
another 5 pounds (maybe more) to the bicycle
mobile weight for the same capacity rating and
would raise heck with my goal of minimizing the
weight that is added by the mobile setup.

The battery pack for the bicycle mobile was built
using four parallel connected lithium polymer
batteries. These batteries were originally
optimized for powering radio controlled electric
model airplanes. Each of the four batteries is
rated at 3.3 AH and 12.6 volts for a total battery
pack rating of 13.2 AH. These state-of-the-art
batteries employ the latest nano-technology,
have a very low internal impedance (read high
efficiency due to low voltage drop under load
conditions) and are good for hundreds of
discharge cycles. The four individual 3.3 AH 12.6
volt batteries are housed in a plastic box
measuring 8.5 inches long x 5 inches wide x 2.5
inches high. The total weight of this 13.2 AH
battery pack is 2 lb 14 oz including wiring,
connectors and the plastic box. Even though the
rig draws up to 22 amps at peak output, the low
duty cycle of the single side band transmission
mode allows this battery pack to power the rig for
up to 30 minutes of talk time while still providing 4
hours or more of listening time. This seems to be
more than antiquate for most bicycle rides. Since
the radio draws only 1.3 amps when receiving the
13.2 AH battery would provide 10 hours of
listening time if not transmitting. The battery box
is mounted directly behind the bicycle seat.

The fuses, that are installed in the factory power
cable and provide protection for the transceiver,
are also tucked inside of the battery box. Note
that if batteries are chosen that cannot support
the 22 amps of peak current required for full 100
watt SSB output, super capacitors can be added
in parallel with batteries that will reduce the
voltage sag during currents peaks.

While riding bicycle mobile, I wear a headset with
an attached boom mounted microphone to
control the radio in VOX mode whenever the
surroundings are sufficiently quiet. However,
when riding in either auto or pedestrian traffic
or when huffing and puffing during a stretch of
strenuous riding, the VOX will often be triggered.
To take care of this, a push-to-talk switch button
has been mounted on the handlebars near my
right handlebar grip. The cable from this switch
is plugged into the connector on the controller
that is mounted on the handle bars.

My bicycle helmet has been modified slightly by
grinding away a small amount of material in area
of the earpiece. This accommodates either a
single or double earpiece headset (although
only a single earpiece should be used when it is
important, for the sake of safety, to be aware of
the surroundings). This modification allows the
headset to fit over the outside of the helmet
when I am riding. This looks a little comical but
works great. The Heil Elite, Heil Traveler and
W2ENY headsets have all been used with equal
success.

The ICOM 7000 has a mike input connector
option on both the remote control panel and at
the back of the transmitter unit. The headset can
be plugged in at either of these locations. After
trying both locations, I prefer having the headset
connected to the main unit behind the bicycle
seat. This allows the cable “adapters” to be
concealed inside of the battery box and also
keeps the headset cable from dangling down in
front of me while I am riding.

For a little more audio punch when using the
Heil headset, which has virtually the same effect
as increasing the transmitter power or the
antenna gain, I set the bottom end audio off at
300 Hz, increase the gain by 3db at 1khz and
6db at 2khz and limit the upper range of
frequencies transmitted to 2.5 khz. If you are
using a microphone with a more limited DX
oriented frequency range this may not be
necessary.

The bicycle mobile transmitter/battery/antenna
support rack system on the back of the bicycle
is a QR Beam Rack MTX unit that weighs 20 oz.
It is attached to the bike seat post with a quick
disconnect fitting. This allows the unit to be easily
removed whenever bicycle mobile operation is
not desired. I have added two additional
aluminum struts extending from the base of the
antenna mount (ground plate) to the bicycle
frame. These struts are made from 1 inch x 1/8
inch aluminum bar stock and provide a much
improved ground return path from the antenna
base to the bicycle frame as well as a measure
of additional support and stabilization for the
transmitter/battery/antenna package. Wing nuts
are used to attach these struts so that connection
and disconnection can be quickly made. Because
of these quick connect features, this mobile unit
can be removed in just a few minutes whenever
mobile operation is not planned, It also allows the
mobile unit to be transferred to another bicycle
with a minimum of fuss. A photo of the bicycle
mobile package, when it is removed from the
bicycle, is shown below.                
The total weight that is added to the bicycle for
this mobile unit is about 18 pounds. This is the
all up weight that is added for bicycle mobile
operation  and includes the Heil headset, the
16.75 foot telescoping antenna and the 12
ounces of brackets and cable that are
permanently attached to the bicycle.  When the
mobile setup is removed, the net weight of
components that stay with the bicycle, i.e. the
controller support bracket, handlebar mounting
brackets, interconnecting cable and assorted tie
wraps, add only about 12 oz to the bicycle
weight. This added weight is not noticeable.

With a vertical antenna mounted on the rear of
the bicycle and with the braid of the coax that
feeds the antenna from the radio connected
directly to the bicycle frame, the RF voltage on
the frame is sufficiently low that it cannot be felt
by touching the bicycle frame (even when
operating at a full 100 watts of power on any of
the bands).  

Now for some information about various
antennas that can be used with this bicycle
mobile. This is the really fun part of the design
process.  Numerous antennas have been tested
on this bicycle mobile and all bands have been
worked mobile from 160 meters to 440 MHz.

First, as a very simple and versatile 6 through
20 meter antenna, an MFJ model 1979
collapsible 16.75 foot long telescoping antenna
can be screwed directly into the antenna mount
spring using it’s 3/8–24 threaded stub. By
adjusting the length of this antenna it will cover
6 meters through 20 meters when set to the
lengths tabulated below.

BAND LENGTH JOINTS INCHES SWR

6          55.0"         2         10        1.1

10        95.5"         4         16        1.1

12        110"          5           8        1.1      

15        131"          6           8        1.3

17         150"         7           8        1.4

20         ALL                                 1.6
  
Note that the lengths will change slightly
according to the particular bike frame that you
are riding. In particular, more length may be
required on the 17 and 20 meter bands.

The SWR measurements were made using a
MFJ model 269 analyzer.  Note that even though a
20 meter ¼ wave vertical calculates to be about
199 inches long (16.5 feet), which is well within the
length of this antenna when fully extended, it will
probably be a little short of resonance when used
on a bicycle mobile. This is because a standard
bicycle can only function as an effective
counterpoise up to the 17 meter band – and
even at that band it is a little marginal.
Therefore, you may need to clip a
small length of wire onto the tip of the antenna
in order to achieve resonance. I use a 12 inch
length of 14 gauge tinned copper wire with an
alligator clip attached at the top of the antenna.

This is a very reasonable option since the wire
can be easily stored on the rear mounted bicycle
carrier when it is not in use. All of this can be
accomplished with an antenna costing about
$59.95.

If you are willing to give up the 17 and 20 meter
bands you can use the shorter MFJ 1977
antenna which provides a maximum length of
12 feet and will still cover the 6, 10, 12 and 15
meter bands. This antenna weighs only 8 oz
and costs about $30. With the spring that is
attached to the antenna mounting base, the
antenna will fold over horizontally without
sustaining damage whenever you go under a
low hanging obstacle. However, it is still a good
idea to slow down whenever you cannot avoid
a low overhang as I am not sure how many hits
these telescoping antennas can take before
they take a permanent bend or break.

An interesting option that I have used with
success (and an option that I routinely use) is
to add a Hustler Model MO-3 54 inch long
extension between the antenna base mounting
spring and the 17 foot long collapsible antenna.
This provides coverage of the 10, 12, 15, 17
and 20 meter bands without having to add a clip
on wire at the top of the antenna when operating
at 20 meters. All of this for an additional cost of
$39.95 - and with high efficiency as well! I use a
light weight spring between the base extension
and the telescoping whip. This allows the upper
section to bend over whenever I hit the
occasional overhanging branch. As a bonus, by
removing this extension, you can get coverage
of the 2 and 6 meter bands by reducing the
length of the telescoping section.

Ham stick style antennas for 10 and 15 meters
have been used with success although they are
not quiet as efficient as a full quarter wavelength
vertical. The usual signal reports that I get are 2
to 3 db lower using these antennas. These
antennas also have a somewhat narrower
bandwidth compared to the telescoping
antennas and will therefore require more
frequent tuning to cover the wider bands. Also,
they typically operate on a single band only.
However, you may find that the shorter length
and easier obstacle avoidance is well worth
making this compromise. A ten meter ham stick
antenna weighs only about 8 oz and costs about
$20. Not a bad option if this is your main bands
of interest.

A buddy pole can also be used. This could make
band changing quite convenient by using the
tapped loading coil arrangement that comes with
this antenna system.  However, I have not tried
these antennas on my bicycle mobile and you
will have to be careful not to catch the loading
coil on overhanging branches. Also, there might
not be a sufficient amount of adjustability for the
loading coil in order to achieve a sufficiently low
SWR over an entire band.

A screwdriver antenna can also be used on the
bicycle mobile. This type of antenna can provide
coverage of the bands from 6 meters to 80
meters (and might also provide 160 meter
coverage with the addition of a supplemental
loading coil). The bicycle mobile with a
screwdriver antenna installed is planned and will
be evaluated at a later date (after one has been
selected and purchased for use on the Roadtrek
caper van). I anticipate that the efficiency will
vary according to the band that is being used
but will be  similar to most automobile mobile
installations or maybe a little less efficient on 40
and 75/80 meters due to the bike’s small frame
size as an antenna counterpoise. Screwdriver
antennas are also quite a few pounds heavier
than a telescoping vertical and can be more
complicated to tune. However, they might be
an interesting option for some bicycle mobile
riders.

For 144 MHz and 430 MHz a small dual band
vertical antenna can be fed from the second
ICOM 7000 antenna output terminal. The 35
watts or so from the ICOM 7000 on these bands
can easily reach most repeaters with this very
simple antenna and it is often sufficient for
simplex operation as well.. This antenna can be
attached at any convenient spot on the rear
deck

A  favorite antenna of mine, from all of the
available choices, is a half wave horizontal
dipole mounted at the top of a two piece
telescoping “painter’s pole”.

However, it is important to note at this point that
due to various overhanging vegetation as well as
the top heavy, wind prone nature of the dipole,
especially when riding with the dipole elevated to
it’s 12 foot height, it is much easier to travel
along most bicycle paths with one of the vertical
configurations. Therefore, unless I want the
maximum performance that is afforded by the
dipole, a vertical is what I use most of the time.
While the initial measures made at my home
QTH forecasted that the noise level floor for the
vertical would reduce the signal-to-noise ratio
significantly (sometimes by as much as two full
S-units), the fact that there is often no noise
registering on the S-meter at many bike mobile
locations, often eliminates this expected
disadvantage. This is really good news for the
prospects of using a vertical antenna on a
bicycle mobile.

In summary, this bicycle mobile has met all of my
expectations. It was fun to build and test – and
has been a joy to ride around San Diego.  After
making over 100 contacts using this rig, it is
always a pleasant surprise when someone asks
if this is really a bicycle mobile.

Some of the special features of this bicycle
mobile include the following:

1. Talk time of 30 minutes and listening time of
4 hours will cover most bike rides.

2. This bicycle mobile can be configured to
operate on all bands from 160 meters to
440 MHz

3. The final layout is adaptable to numerous
and varied antenna types.

4. The weight that is added to the bicycle during
mobile operation is about 18 pounds.

5. This mobile configuration only adds 12 oz to
the bike for the components that remain on the
bike when the mobile is removed.

6. The 100 watt output power level adds signal
punch that comes close to equaling most fixed
stations.

7. Bicycle mobile allows the operator to seek out
locations where there is a very low noise level.

8. Bicycle mobiles can reach sites with great
views and fantastic signal launching possibilities.

9. The transceiver is easily removable from
bicycle for use in an auto, home or portable
application.

10. This bicycle mobile makes a great toy that
will provide many years of enjoyment by
combining bicycle riding with our ham radio
hobby.
BICYCLE MOBILE ANTENNA TESTING AND SELECTION – THE BACK STORY
Before the first bicycle ride was made along the
Pacific Ocean beaches, a number of antenna
tests wire conducted at the home QTH as
described below.

The antenna test stand for my bicycle mobile
antenna “development” project used my old dirt
bike which was tied along side of the cedar fence
in my back yard. This bike was used as the
counterpoise for vertical antenna tests and as a
“support” for horizontal dipole testing. Either a
vertical antenna or a horizontal dipole antenna
could be mounted on the bike for testing.













































For this first round of tests, the antennas that
were to be tested were configured for the 17
meter band. This is because there is almost
always someone available to talk to during most
of the day. However, note that by changing the
length of the vertical and by adding different “
pig tail” lengths of wire connected to the ends
of the horizontal dipole, either of the antennas
can be easily resonated on the 6, 10, 12, 15,
17 and 20 meter bands.  

For these tests, the ground braid for the vertical
antenna feed cable is connected to the bike’s
frame with a short length of braid. The frame is
resonant at little over 18 MHz which makes it a
marginal but workable counterpoise for a vertical
antenna operating on 17 meters. The horizontal
dipole is suspended up about 13 feet above the
ground level using a telescoping “painters pole”.
The feed cable is not connected to the bicycle
frame. For these tests, both the vertical and the
horizontal antennas have been isolated using a
current balun at the antenna end of the coaxial
cable. This keeps any significant current
unbalance from appearing on the braid when
the cable enters the shack. Baluns will not be
used for the final bicycle mobile antennas.
Both antennas of the test antennas were
connected to the transmitter in the shack using
150 foot lengths of type 1318FX low loss coaxial
cable. The Alpha amplifier in the shack can be
used either as an antenna switch for the
Kenwood TS-590S when running QRP to 100
watt levels or can be used as an amplifier
providing power for antenna performance testing
up to the legal limit. When direct A-B comparisons
are desired, the vertical antenna is mounted on
the bicycle and the horizontal dipole antenna is
mounted nearby on a “field day” tripod. A quick
press of one of the antenna select buttons on
the Alpha immediately picks the desired
antennas.

The vertical and horizontal bicycle antennas
were compared during a large number of side by
side tests. The performance of these antennas
could also be compared with the "house" hex
beam and vertical dipole antennas. These
comparisons could be made almost
instantaneously using the A-B-C-D switches on
the Alpha. Both near by and long distance tests
were conducted and yielded very consistent
results.

Using the horizontal dipole the typical results
might be S7 signals at QRP levels, S9 signals
100 watts and S9+10 signals at 1000 watts.
With the bicycle vertical, the results at the
receiving end were typically 1 1/2 S-units lower
than for the bicycle horizontal half wave dipole.
The noise floor for the vertical ranged from
about the same as the dipole (on a very low
noise level day) to 3 db higher under most
typical listening conditions.

This led me to choose the horizontal dipole as
my initial bicycle mobile antenna.

The final horizontal dipole configuration that I
arrived at uses a two section telescoping
fiberglass “painters pole” to raise the dipole up
to about 13 feet above ground level. The
horizontal elements are made up of two light
weight 7 ½ foot long fly casting poles with the
antenna wires fed through the loops along the
length of the pole. The additional wire length that
is necessary to resonate the dipole at 17 meters
drops down from the ends of the fly casting pole.

The horizontal dipole antenna weighs about 4 ½
pounds including the balun unit at the top of the
dipole. A lightweight cable and the elimination of
the balun assembly should bring the weight down
to less than 3 pounds.

On my first trip to the Pacific Ocean beach, late
on a Tuesday morning and with ½ hour of talk
time stored in the batteries, the contacts that I
was able to make this first outing were extremely
encouraging. Honolulu was my very first contact
followed by a lighthouse off the coast of Alabama,
a VE4 and a half dozen other stations across the
states. I even worked local contact in San Diego
which I normally find very difficult on 17 meters.
The interesting part of this first adventure into
bicycle mobile was that with the pileups that I
was getting I could have worked many more
stations if I didn’t talk so long on each of the
contacts. However, having a nice QSO, especially
on bicycle mobile, is what I find the most
satisfyingly. This has real possibilities, I thought.

Since the Kenwood TS-590S weighs over 16
pounds and is quite bulky for a bicycle mobile, a
much more compact and lighter version of the
bicycle mobile was soon hatched as described
at the beginning of this story.
THE FIRST TRY AT BICYCLE MOBILE
All-band 100 watt bicycle mobile with 10 meter hamstick antenna installed.
THE FINAL BICYCLE MOBILE DESIGN
This page was last revised November 10, 2015
THE FUTURE OF BICYCLE MOBILE AT W6SDO
After peddling my relatively heavy bicycle mobile
around the San Diego bike paths for a couple
years, sometimes towing a trailer containing a
60 pound 27f deep discharge battery, it is time
to consider some improvements.

The highest priority improvement that I am
thinking about is to add electric motor assistance
to the bike mobile. This would help out by
making the return leg of long rides much easier.
In addition, it would expand my riding
area to include longer rides as well as those
rides that would include a few hills.
First, I could add a simple peddle assist kit to
the present mobile bike. Second, I could buy
one of the new purpose built electric bikes and
transfer my radio equipment to it.

To help with the decision I recently took a test
ride on a state-of-the-art electric bike. I am very
impressed with how much fun they are to ride.

The bike that I tried out has a 48 volt battery and
a 500 watt (plus) motor. The range is 20 miles
without peddling and up to 40 miles with peddling.
I rode up a 30 degree grade and the bike it would
maintain 6 mph without any peddling! It has a top
speed of 20 mph on level ground which it does
with ease.

The next step was to rent one of these bikes for
a day and do some tests to determine if the
electric bike under consideration (1) is effected
by a nearby ham radio signal or (2) generates
QRM on the ham bands.

The results of this testing revealed that the  
bike's control system was
not effected by the by
the immediate proximity of my 500 watt mobile
station.  However, the bike did generate some
QRM on the 10, 12 and 15 meter bands.

After adding snap-on ferrite cores on all of the
wiring branches, the noise was almost, but not
completely, eliminated.  However, I believe that
this problem can be minimized with a few more
cores and maybe it can be completely eliminated
by adding a shield braid around some of the
wiring.

Picture the bike in the photo with its quarter wave
vertical antenna connecting it to the world of ham
radio from the boardwalks along the Pacific Ocean.

  STAY TUNED            
       
.ELECTRIC BIKE MOBILE UPDATE   11/10/2015

    The 100 watt mobile transceiver and battery package is almost completed for the new electric bike  It
will be hung from the handle bars so that it can be quickly attached or removed. Several antenna
configurations have been tested and the fabrication of the final antenna mount is nearing completion.
Should be riding the bike paths around San Diego with this new bicycle mobile by Thanksgiving 2015.
See you on the bands soon from the new bicycle mobile. 73, Bob
Transceiver package including
IC-7000 and lithium battery pack.