Yakima SteelHead bike racks for use on Yakima round bar roof racks, $20 each.
These are the type that you remove the front wheel and clamp your bike's front fork into and use a wheel strap to hold the rear wheel in the wheel tray.
They are lockable with the addition of Yakima SKS lock cores, not included.
I also have wheel forks available to mount your front tire to the rack, $10 each.
I prefer you call me (no texts) as I do not check email very often. If you do email me, include a phone number if you expect a response.