How to set keyboard repeat delay and speed in Ubuntu Gnome 16.10?

These settings are under Settings → Universal Access → Typing → Repeat Keys. You have to click the Repeat Keys row item, which brings up a pop-up dialog with two settings: Delay and Speed.

This works in Ubuntu 17.04 and above.

In older versions of Ubuntu, the Speed setting worked in reverse: the lower the speed, the faster the repeat rate. This is no longer the case.

On ubuntu 14.04 and up this will survive after reboot:

gsettings set org.gnome.desktop.peripherals.keyboard repeat-interval 30
gsettings set org.gnome.desktop.peripherals.keyboard delay 250

If nothing else works, try running xset r rate 220 40 from a console.

For me, the HID layer got broken in some way and config GUI didn't work, gsettings didn't work, only xset worked.

This solution however is not persistent - will disappear on restart (unless added to ~/.bashrc).