I bought a Shimano Deore front deraileur off Ebay and when it arrived I was surprised at how much the little thing weighs. I don't handle parts enough to really make any weight comparisons. Are there any mechanics in the house that can tell me--- is there much difference in weight between the different brands and qualities of front deraileurs?

Thanks,
Bob

"is there much difference in weight between the different brands and qualities of front derailleurs?"

yes

But it's clearly not enough in the grand scheme of things to matter. Look up the difference in the weight between a Deore and XTR derailleurs and then reduce the water in your hydration bladder by the same amount. You won't even notice the difference in bladder inflation status. And if you typically finish your rides with water in the bladder then just fill it a bit less and you'll hae your XTR like weight advantage.

Yes and no. Maybe its worth describing some things that influence weight.
They all have one thing in common - the need to physically push a steel chain to one side or another. That requirement pretty much eliminates anything except steel as a cage material simply due to wear characteristics of the metal. However, the direct mount front derailleurs will weigh less than the models than clamp to a frame, and models with steel clamps will weigh more than models with alloy clamps.
Any derailleur designed to handle narrow chains will have a narrower cage and therefore be marginally lighter.
Suggest yo try a few different models if your friends have them on their bikes. There is a slight difference in the effort needed to shift between some models and that may be more interesting than any weight differences.

For the record, XTR front derailleurs have used aluminum cages in all the low-clamp models since the 950 series, with the sole exception of the 985 variant that's built for 2-ring XTR Race cranksets. I believe that holds true for e-type as well. Dura-Ace has also used aluminum FD cages since the 7700 series. Aluminum cages hold up OK, I think they're just expensive to make.

On the original topic... for the abovementioned reason, a low-clamp XTR FD would be the only Shimano mountain model that'll really give you a meaningful weight loss, and that's a lot of money, so the best bet is to stick with your Deore. Some weight-weenies will use a Dura-Ace front derailleur with a Speen pull-ratio adapter, which is considerably lighter yet.

Don't they give the ally thick nickel plating or something? I seem to remember something like that...

I reckon the optimal cage would be carbon with like .5mm stainless wear faces. But that's hilariously far into the land of diminishing returns...

Yeah, Dura-Ace and XTR aluminum FD cages are nickel-plated. As for carbon FD cages, Campagnolo's been there, done that. They actually hold up tolerably well too.

Thought I'd seen em... looks like it's just the outer plate, which has a much easier job of it... inner looks like ti.

Wonder how they're secured, or do they move separately? That'd be cool.

The inner one is plated aluminum on that one. They're rigidly connected to eachother. SRAM does use a titanium cage on the Red front derailleur. The only FD I can recall that had an articulated cage was the old XTR 950 series, which we still have a few lurking in the basement at the LBS, mostly e-type.