Spare link - I keep this taped to my brake cables up front.

Keep your spare link taped to the front brake cables, so you'll notice if this falls off.

Tape the tube to frame, all bikes will have a safe place to do this. Both riders should have a tube.

A tyre lever and CO2 - easy to access and will not rattle loose.

A 650b light tube at 210 grams compared to the Schwalbe 29er EVO tube at 76 grams.

Tip: take your tubes to a butchery, get them to vacuum seal them.

A SahmuraiSword plug (fits into your handlebars) is a great option.

Standard SahmuraiSword plug.

You can also carry a spare tool set on the bike, there are systems available that attach to bottle cages and other parts of the bike.

SahmuraiSword plug with the zip ties taped to the reamer and spare plugs.