The ribbon control has full keyboard access. Enter keyboard mode by pressing the ALT key and then select
the required option. You can see in this image the options you are initially presented with.

If you pressed H to navigate into the Home tab you would then be presented with the following set of key options
based on the contents of the tab.

Pressing B would then reduce the display options to only those that start with the letter B.

Try out our many ribbon samples to see this and other ribbon features in action.