Bicycle Mechanics - how to remove french headset/fork

i've never done this before so bear with me. in all the tutorials i've seen, the threaded top race has wrench flats so you can use a wrench to remove it. i have two vintage french bikes and neither of them have the wrench flats. how do you get it off? do you clamp it? seems like you would need a large pair of strong vise grips. or am i missing something obvious here?

Once you get the top/locknut off (which has wrench flats), there isn't really anything holding the top race back. It should unscrew with marginal force.

ahhh, that was easy. thanks!

ahhh, that was easy. thanks!

Now, getting it back on - that might be the challenge.
Probably you have one of those big washers underneath the locknut with an internal tab that's supposed to fit in a vertical groove milled out through the threads to prevent the transfer of torque to the top race. That tab is more than a little prone to shear right into the threads instead, given half a chance. If you have a robust attitude towards your bike I'd recommend something like the vise grips you mentioned.
If you are of a more delicate constitution there are nice tools meant for replacing oil filters that do a good job of holding onto cylindrical items w/o scratching which you might want to consider.

French steerers don't have a groove, they have a flat at the rear of the steerer. There are no wrench flats because there is no need to use a tool. Hold it with your hand. Don't ruin the part with pliers.

French headsets often use a lock ring that has either a pin or teeth to keep it from turning. You just have to lift straight up to remove them.

French steerers don't have a groove, they have a flat at the rear of the steerer. There are no wrench flats because there is no need to use a tool. Hold it with your hand. Don't ruin the part with pliers.

Good info, and a sensible design. I guess they had to make something to atone for their bottom brackets...

The right-threaded fixed cup was a bad idea, but the Italians made the same mistake.

They liked round metric numbers, but they were alone,
as the rest of the world used Fractions of an inch
translated to metric so 22.2 rather than 22.0, 28.6 rather than 28.0

The VAR #78 is designed for this purpose, but judicious use of a wide-jaw pliers also works.
http://www.os2.dhs.org/~john/var78.jpg