Night pics with big background & foreground subject

[Chromo]

I want to take a photo of an object, in front of the Harbour Bridge at night.

I've taken a few night shots of the bridge and the opera house before (so I am aware I'll need a tripod, slow shutter speeds and a large depth of field). But I've never taken night pics of an object with big things in the background and googling hasn't helped so far.

Is anything different when there's a foreground subject added to the mix of a traditional night bridge shot?
Will the available light from the long exposure be enough to illuminate the object, or do I need to use a flash so the object in the foreground is illuminated?

I'm asking because I don't know if I'll have time to do test shots, before I need to do this for a group and I'd hate for none of the pics to work.

I assume if I do need a flash, I'll have to buy one, as the camera flash probably won't be effective enough - is that right?
(I have a tripod, a Nikon D70s and a Nikkor 18-70mm lens)

[merlin]

Whats the object how large small?? colour? How light is the area your thinking of going to?

[Analog6]

Whether camera flash would do will depend on the object (size, colour/luminosity). One way is to do the long exposure and then use a manually operated flash at the end to illuminate the object. But you would have to practice, I imagine. Someone on here may be able to offer advice.

If you are in Sydney you could proabaly hire an off camera flash, and I'm sure you can download instrcutions for them on how to fire independently from the camera (if they do not come with the hired equipment).

[Chromo]

Sorry - the object is a motorbike (or multiple motorbikes).

I think you're right Analog. I'm just going to have to find a way to practice it first.

[latino]

Maybe you can take the photos around 20 minutes after sunset so you still have some light which you can use to your advantage. You can use exposure lock to lock in the exposure of the background and use a flash to illuminate the bikes in the foreground.

Just an idea.

[ricktas]

You can also illuminate the foreground subject with Torches etc.