Looking at building a seattle winter commuter bike based on a cross check frame.

nexus 8 sp hub in the read w/ roller brake. for the front, I'm eying the SA xfd front hub. I want to avoid rim brakes.

Here's my question: VO is now offering a dyno hub that is switchable, so you can lose the resistance when you don't need the dynamo. Does anyone know of a hub that combos a switchable dynamo with a hub brake? SA makes a brake/dyno combo hub but it is not switchable.

Thanks much!

The resistance on a dynohub is so low that you'll never notice it, even if you leave your light on all the time. Go with a Shimano 3D80 and a disc brake. It means having to swap out the stock Cross-Check fork, but plenty of replacements are available.

The resistance of the Shimano DH-3N71 Disc hub is barely noticeable on a commuter bike. The switch is in the light,I use a B&M senso and feel no difference if it is on or off.
Discs work well in wet, mucky winter conditions.

Another happy Shimano disc hub user here. I don't know anything about the SA hub, but if your only concern is about the rolling resistance, it's negligible with the light on and goes away if you can switch the light off.