BikingBrian Rotating Header Image

Mounting a Ham Radio Antenna on a Bicycle

My initial interest for mounting an antenna on the bike was to do on-bike radio support (I am a licensed ham radio operator) for charity bicycle rides.

First Generation Setup – October 2012

I started with a Comet SBB5 antenna. It does not require a ground plane, giving me more flexibility with mounting options. I used a Minoura saddle mount bottle cage holder, but flipped it upside down. That gave a flat surface for mounted an aluminum plate. Then I drilled a 5/8″ hole and mounted a Diamond C101 cable assembly

IMG_0881

Here’s a better view of the whole antenna.

IMG_0880

And a view of the bike.

IMG_0887

The thin coax made for easy routing along the bike frame. It was easy to roll the excess into a loop in the front. The HT (handheld transceiver) sits in a Topeak Handy E-Pack. I used to have a headset, but that was cumbersome with the bike helmet. So the handheld microphone/speaker works just fine. And there’s enough room to be able to see the Garmin Edge 500 (which has since been upgraded to a Garmin Edge 800 with mapping capability).

IMG_1032

Second Generation Setup – December 2013

While the prior seatback antenna mount was pretty solid, this update was driven by not wanting to bump into the antenna when sliding back on the saddle. I also came to the realization that I don’t need to have the antenna on my fast road bike, since my bicycle mobile duties usually have me riding sweep. So I decided on a rear rack antenna mount for the second generation. I also have some other thoughts about using that for APRS tracking during multi-day self-contained bicycle touring in the future.

My constraints for rack mounting are to not interfere with panniers or a rack top bag. That pretty much leaves only the option of cantilevering the antenna off the rear. Still I had an idea. The parts are below, first generation setup on the left, second generation setup on the right.

IMG_2433

I used a piece of 1″ square aluminum tubing. I could have really gone bigger, but that’s the biggest stocked by the big box stores. Anything larger would require ordering online and paying $12 to ship a $3 piece of aluminum.

Since I used smaller tubing, I had to cut an opening in the bottom in order to get the antenna mount on to the bracket. That opening didn’t significantly compromise the strength of the setup.

The unused hole on the inside of the aluminum? I’ll get back to that a little later.

IMG_2464_edit

This gives a much more comfortable distance behind the saddle.

IMG_2466_edit

Oh, that unused hole in the bracket? Well, I had originally planned to run bolts from the rear light bracket, all the way through the aluminum bracket, and into the rack, using holes had I previously drilled in the rack for the rear light bracket. (This is a photo of my tandem bike, but it has the same rack as the touring bike.) While those holes in the rack had not previously compromised the sturdiness of the rack (even when loaded touring) when they were used only for the rear light bracket, I thought that the added stress from the antenna on the rear could pose a problem. So I have a replacement rack on order, which I found on closeout for $25!

IMG_2467

 Update: Generation 2.5 – February 2014

Just a minor update to this post to show the “cockpit”. Garmin GPS, radio in the Topeak bag, and the iPhone is for optional navigation.

DSCF2133

I got a new rack to replace the one with the holes, here’s an updated photo of the complete bike.

DSCF2131

xxx

3 Comments

  1. Ken says:

    Nice use of the adjustable clamps. Definitely better than drilling through the rack in that location.

    I’m interested too in the large-ish hole in the “bottom” of the square tubing. Is that just for weight savings? And if so, how were you able to determine what amount you could remove without compromising the strength of the square tube?

  2. Ken says:

    Oh, and how is the light bracket supposed to mount “normally”? I’m sure they don’t recommend drilling through a rack.

  3. BikingBrian says:

    I could have explained it better up top, but if you go to the link for the Diamond cable assembly, the fitting where the antenna attaches is about 1.5″ long, which is too long to insert in the side of the 1″ aluminum box tubing. So the hole in the bottom was to able to get the cable assembly in the box tubing. Even with the big hole, the box tubing still appears to be strong enough.

    The plastic light bracket “normally” is mounted to an “L” shaped bracket which comes with the rack. Then the “L” bracket is mounted to the rack.
    http://ecom1.planetbike.com/planetbike/media/3108LBracketwebdetail.jpg

    Though there’s two problems with that here: (1) my rack design is a little different (no top platform) and so there’s no way to mount such a bracket to the rack, and (2) those brackets are wimpy and always break – I’ve had three of them break on other racks.

Leave a Reply