I ride around the city (for hours at a time, usually), and take day trips on the bike to nearby locations quite often. I simply carry the 4x5 field camera, four lenses, filmholders, filters, meter, etc. in a backpack. The tripod is bungeed to the carrier rack on the back. It is a bit longer than the rack, but mounting and dismounting is no problem. The pack is a cheap backpack/rolling suitcase hybrid of carry-on luggage dimensions. It has wheels and movable front legs plus a pull-out handle that allows me to dismount, take off the pack and roll it around when I decide to walk for a while. I also stands nicely inside the tripod legs when working, allowing easy access to everything and staying well in sight when I'm under the focusing cloth.
The setup works well, and my body cushions the shock from road bumps. That said, after a few hours without a shot (when I get to dismount and take the pack off), I really begin to feel the pressure from the saddle. The extra weight can give me a sore butt the next day. Plus, me and the bike are a little less stable with more weight up high. I have to be careful in corners, when going very slow or very fast, and in situations that require any maneuvering at all. Usually, however, I'm just cruising slowly and not taking any chances.
If I were doing long(er) trips, or spent a lot more time on the bike with the camera, I would invest in shock-mounted panniers and some closed-cell foam packing material. As it is, homemade cardboard boxes for camera and lenses stacked in the backpack seem to do well.
The trick for me, as with backpacking and hiking, was to get the weight of the kit down to a minimum. For this kit, I have a Woodman 4x5 field that weighs in at under three pounds, four smaller lenses (SA 90mm f8, 135mm plasmat, Ektar 203mm f7.7. and Fujinon A 240mm) a set of 52mm and 67mm filters, a Pentax digital spot meter, a few accessories and 6 filmholders. This comes to just under 22 pounds. Not too bad to pack on your back. I'm watching out for symptoms of neuropathy, though...
Hope this helps
Doremus Scudder
www.DoremusScudder.com