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What's the smallest multi tool with a chain tool that's of decent enough quality for it to be functional when you need it to be?
Leyzyne V10
I got [url= http://www.specialized.com/gb/gb/ftb/bags-tools/tools/emt-mtb ]this[/url] Specialized one which is pretty small but ok to use (I have that V10 ^^^ up there too, it's a bit bigger than the EMT.)
You could always get a chain tool that [url= http://www.specialized.com/gb/gb/ftb/bags-tools/tools/top-cap-chain-tool ]fits in the steerer tube[/url] then get a properly small multitool.
Another vote for Lezyne V10 as I have used it a few times to break/repair chains during rides
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I never feel that multi tool levers would be much good.
I always carry a set of Pedros and if i feel the need for a bigger multi tool,it's [url= 
]one of these[/url]
http://www.planetx.co.uk/i/q/TOJWJEPT/jobsworth-spygadget-folding-tool
Good price as well, I have found all of the jobsworth tools to be good.
I carry both a multi-tool (Crank Brothers Multi 10) and chaintool (Park CT-5), both work very well, unlike some others I've tried/used.
IMO for these kinda tools, been small/light is probably less important than actually working properly when out in the middle of nowhere.
I really like the Topeak Mini 20 Pro, it's not the absolute smallest out there but it is pretty damn compact, the chain tool works well, it's bombproof and it has everything you need on it.
+1 Topeak Mini 20 Pro
All you need to know about the Lezyne multi-tools is that they sell the chain-breaker section as a spare part. Go figure. The things are made of cheese 😐