Front brake effort fluctuation

[runnerhiker]

Is the front tire cupped?

I am not quite sure what you mean by fluctuation. If you apply the front brake and you feel a pulsing fluctuation at the lever, then tire cupping is probably the reason. If by fluctuation you mean the amount of effort (force) applied to the brake lever (sometimes needs lots of effort, sometimes needs little effort), the cupping is not something to look at.