this setup is working pretty well for me now.
total weight with the FX lens is just a hair over a kg, 1060 with the strap, lens, camera, battery, card. the dx lens drops that by 60g, which is not consequential and cuts resolution in half. better to go with the z50 in that case, for 775g total. again, i'm not sure 285g is worth such a big loss of resolution. the camera stays put back there until i reach around and pull the little clip forward. doesn't really bother me 99% of the time, every once in a while getting out of the saddle it shifts a bit to the side, but that's rare and it's not like i'm racing anyone.
i'll probably bring this with me on any rides i expect to have good light (haven't had one yet, but looking forward to one of those rare clear summer evenings in the headlands...) or longer rides with opportunities to get off the bike for a few minutes here and there.
(and yes, those are the clothes i ride in, MTB shorts and a jogging shirt. not a fan of the skin-tight stuff, again, not racing anyone!)
