Brucey wrote:if stuff is small and light it is better to carry it and not need it than the other way about.
Fetishistically choosing to leave ~50g of stuff at home is just daft.
Which is all fine and good if you know how to use the tool, fit the part but pointless otherwise. As a teen I had a tool roll under the saddle that contained more spanners, keys etc than I could ever have found useful (it must have weighed a full kg at least!). One day, unbeknownst to me, I managed to lose the whole lot, only discovering the loss when I got home. After that I only carried the essentials for a puncture and that was more than enough for my road bike riding for over 30 years.
I only added to that when I started riding mtb's and then when I started touring. I have had chains break so I carry the gear that should get me home for that, likewise multiple punctures. A decent multitool will get me sorted with the majority of potential issues. If
I broke a spoke on a day ride, well its a day ride, that's where the twenty comes in or maybe International Rescue!
Not sure anyone here has suggests a full set of spanners at any point.
I have a Topeak Mini 18+ tool. It has 2*2mm, 1*2.5mm, 1*3mm, 2*4mm, 1*5mm, 1*6mm, 1*8mm, 1*10mm, a chain tool, a flat & philips screwdriver, 14g/15g spoke wrenches, some horrible tyre levers, a t25 torx key, and a pad spreader.
I'm not really sure I could necessarily use all of these tools on my bike at all, and some others I doubt you'd use on the road unless you were on a world tour or something, because you'd have better ones at home.
I think 8mm is for chainring bolts, pedals, 10mm maybe for freehub body. I'm not sure if I have 6mm bolts on my bike (probably with cable brakes, not so much with hydraulic). 4mm & 5mm are the main ones. 2.5mm, 2mm, 3mm, maybe MTB grips? Perhaps bleeding ports on hydraulic brakes. But not necessarily something just 'on a ride' with a road bike.
The philips screwdriver ok for derailleur screws, flat not so much. Tyre levers completely horrible, torx key probably not. Pad spreader not really necessary in any case but in any case a bit useless without a pair of pliers.
So probably I'd only really use the 4mm, 5mm, chain tool, philips screwdriver, maybe spoke wrenches. But the 'multi' is not really realistic, because multi tool is just for emergency really.
I think Topeak make even more ridiculous tools with 31 functions.
This is rather more streamlined (4,5,6,8mm, screwdriver, chain tool, no horrible tyre levers from hell) and is always there in case of emergency https://www.sjscycles.co.uk/tools/pedro ... ulti-tool/
The same manufacturer's tyre levers might complete your toolkit along with a tube and pump.