I just carry 3-4 different size hex keys which also doubles as tire levers. I don't carry any other tool on the road with me, I'm never much further than 70 miles from home and could always limp the bike home if necessary. To define "limp," I once rode ~40 miles on a busted chain using an old zip tie, to this day I'm still surprised that worked. I couldn't shift and I had to walk up hills but I made it to my destination.