I carry around most of what I'd need to assemble and disassemble 75% of my bike and also repair and reinflate a flat tire in my bag with me at all times... and it's surprisingly small. The few hex wrench sizes I'd need (seat, seatpost, stem, headset adjustment, etc), a 15mm wrench (pedals, wheels), tire levers, CO2 inflation kit, patch kit and ehh.. that's about it. I just don't have specialty tools like a chain whip or lockring wrench on me all the time.. those are at home.