Will a 6700 front mech work with 11 spdeed shimano sti’s 5800?

Yes.

Even if it did work I wouldn’t use it. The 11spd front mechs are so much nicer than the 10 speed ones.

I thought the pull and length of the lever arm was completely different.

Different cable pull ratio.Might bodge it tho.

Not tried it myself but the arm on the mech is a totally different length on the 5800 which would lead me to believe the cable pull at the lever is not the same.

may or may not actually work … have a read of the below ..

http://velonews.competitor.com/2015/03/bikes-and-tech/technical-faq/technical-faq-shimano-11-speed-front-derailleur-cable-setup_363733

It does work fine. Not as well as the far superior 11spd mechs but it works fine.

its doesn’t work properly, we tried last week, and the customer ended up getting the 5800 front mech which was not very expensive.