I often call in as a chaser whilst bicycle mobile. I have recently improved my bicycle setup by adding an antenna to the rack. This is a big improvement to having a HT with quarter-wave whip stuffed in my Jersey pocket
Thought you might be interested to see the setup i use.
Anyone else with a bicycle mobile setup…I would be interested in how you mount the radio
More adapters needed 
A couple of years ago, instead of its usual home on top of the car roof, I mounted my Watson W-627 6m/2m/70cm tri-band whip antenna on the metal pannier rack at the rear of my hybrid bike with a small L-shaped bracket. I taped the coax feeder to run under the frame’s top tube to the HT in a handlebar bag so I could monitor the calling frequency whilst cycling. I would always stop in the event of wanting to transmit.
I never tried operating whilst cycling but I remember - having cycled up the dirt track skirting my local (Sandside) quarry - getting good reports when I joined an ARS club’s weekly 2m FM net. I concluded that the bike and I provided an adequate ground plane.
On the down side, one can get freezing cold standing around in cycling togs at a windy location watching the sunset waiting what seems like an eternity for one’s turn in one of those nets.
I use a simple, cheap X shaped rubber thing for attaching my phone to by bike when needed.
It was in the bargain bin at Halfords and it is similar to your system except it had a curved moulder part in the middle to grip the bars better.
If I mount it on the stem, the pinch bolts on the top keep it stable and stop it rotating around.
Lots of people recommend the quad lock mounts for phones, Chris Froome gets paid to rave about it in the adverts 
The FT5D is a bit heavier than a phone so I’m not sure the stick on mount will be strong enough but you might be able to modify it to use the screw holes for the belt clip.
You win the prize for actually finding a constructive use for potholes Matt. I reckon they must be expecting the Tour de France to visit here!
You need seven more turns on your handlebar choke.
I use quadlock on the motorbike. It works really well, but a bit like powerpoles or apple devices they are great but end up costing a fortune if you buy into the system.
Mark
Suggest adding some radials at the base of the antenna, or at least one going backwards. Otherwise you are counting on the outer of the braid on the coax to act as the ‘other half’ of the antenna. A resonant quarter wave radial or better, two, would improve the efficiency and avoid proximity effects for the coax cable and the operator. Either that or put a 9 turn choke on the coax at the 1/4 wave point, like the flowerpot vertical.
Neat setup though.
Thanks for the tip, i will give that a try
There are no radials when I use the mobile whip on a magmount on the car roof. I assume the metal roof provides a ground plane in that case. Isn’t the metal bike, pannier rack and even the human rider providing a ground plane albeit not as large or effective as the car roof?
I have some spare arrow shafts, left over from arrow antenna project, or perhaps could use a spoke.
Will connect the nano vna to it and see if it makes any difference
Stick a reflector on it for a stealth (or not) radial:
Andy,
Your car roof approximates to an infinite ground. Rough approximation but I would expect someone like you would own a vehicle with an expansive roof. 
A bicycle frame is, well who knows without measuring it just what it approximates to. The rider probably adsorbs more RF the he radiates.
Still if you get contacts, keep on keeping on.
73
Ron
VK3AFW
Did some back up comms for a bike ride over 6 days one time over 700km.
I had an independent to ground half wave 2m antenna on my touring rack bolted to a steel frame bike. A small Yaesu hand held on my hip bag and 12v battery on rack as well. 5w output worked as good as the mobile stations helping out with the exercise. Speaker mic clipped to my helmet strap made it easy to chat on the go including all the puffing. The main thing to remember was take the handy rig off my bum bag and leave it with the bike before I walked away from the bike. Good fun bike mobile.
vk5cz …
Whereas I own trousers with expansive waist bands.
This reminds me of my bicycle mobile attempts at 40m.
Oh dear, I had a few extra pounds back then.
73 Chris
Are you aware that operating a radio which requires holding a mic while riding a bike comes under the (I think) cell phone while driving laws, i.e. they consider it dangerous.
As others have said, you need a better ground plane, BUT use something soft and flexible so that it doesn’t injure anyone (including you) in an accident. Likewise, the tip of the antenna whip needs something blunt on it.
Yes, that’s of course very dangerous, especially when using SW. After few trials I have stopped my riding qrv activity. 
73 Chris
In the UK a police spokesman said:
“There is no specific offence for talking on a mobile phone while cycling. However, you could be prosecuted for careless or inconsiderate cycling contrary to section 29 of the Road Traffic Act 1988.”
If you are pulled over, you can probably expect at least a talking to – “words of advice”
I agree a handheld HT / mic would be considered like a mobile phone.
I doubt simply monitoring / listening to the radio without touching it would be a problem. But pull to the side of the road and stop before “operating” the radio. Of course, if you are not on a public road, you can probably do what you want.
Have you seen this chap ? https://www.g4akc.co.uk/ I have worked him a few times when he has been out and about - mainly along Blackpool prom.
