I have tried various items for carrying my K100D when bicycling. None were satisfactory.
A handlebar bag had me concerned about vibration on bumpy terrain as did a bag on the rear carrier.
The Op/Tech Camera/Binocular harness was difficult to adjust, awkward to put on, uncomfortable and allowed the camera to hang free and bounce against my chest.
Sometimes the simplest device is the best.
This photo shows my camera hanging around my neck on its usual Op/Tech neck strap adjusted to my preferred working length.
It is secured to my body by an inexpensive
elasticized belt.
The belt is fully adjustable and quite comfortable.
The belt holds the camera securely against my body even when using drop handlebars.
When the camera is in use the belt is not even felt around my chest.
I prefer to put the belt around the camera lens to keep out of the way and prevent it from banging against anything when I am not on my bike. Occasionally I may place the belt across the bottom front of the camera. It will also hold the camera vertically.
On long walks the belt can be used to relieve the weight of the camera on the neck.
When I put on the belt I slide the buckle around to my side so it cannot mar the camera.
The camera in the picture is a Canon T90 with a Sigma 70 to 210 mm lens. It is substantially heavier than my K100D.
The belt came gratis with a pair of slacks. The frown is the result of trying to get a reasonably framed picture shooting with my K100D down at my hips. It took 8 tries.
Mickey