Well, depending on your exact requirements you could simply mount a bar-bag on your handlebars. I do this and can lay my hands on the camera within a few seconds. Most bags will take a 35mm + zoom & some will take MF equipment. By the way I have never had any problems with vibration causing damage to any of my cameras when carried in a suitable pannier or bar-bag on any of my bikes, over a period of 25 years or so.