I suppose the answers here depend which pack you’re using. I’m using a Mule with a 3L bladder, take just over 2L with some hydration tablets in and almost always drink the whole 2 litres.
bike/pads etc always checked over etc before a ride
small tool compartment at the bottom
– chain breaker (been used 3 times in the wild in the past 2 years)
– quicklinks (new addition)
– selection of allen keys in a zip lock bag (also been used)
– tyre levers
– a few zip ties
– a few bits of clean workshop blue towel
– small flat head screwdriver suitable for mech adjustments
– small pliers
– spare gear cable
– some “leaches” puncture patches
– old school puncture repair kit
– number of energy bars required + 1
– car keys
main compartment
– OS map of where i’m riding (even i’m riding home turf, as its good for discussing things or helping lost people)
– mini tyre pump
– shock pump
– spare tube
– cheap/small pack a mac in case of an extreme downpour
– sunglasses with clear / changeable lenses
– a tube compression bandage thing (good for turned ankles/sprains)
– pair of neck/face wrap snood things to go full ninja
– other set of riding gloves (long and short finger, depends what i’m wearing)
– a mud/rain cover as the camelbak doesnt have an integrated one
– digital camera
– wallet
media compartment
– charged iphone in waterproof case, strava’d up
so basically, not carrying a trox 10, a bleed kit or a workshop stand?
prior to the camelbak i used a small pack with tools, and two bottles, but now i’m on a full susser which can’t take two bottles with ease (santa cruz superlight) i made the switch. i love the hydration pack now. bottle mounts have even been replaced with lightweight plastic replacements.so there’s nothing on the bike, no silly underseat bag or bottles its all on my back.
i’ve had friends lose bottles and those underseat bags.
in my experience, chains, by far break the most, followed by punctures. only other thing is badly put togother new bikes – have had to fix a friends bike on which the stem was loose and would turn on bumpy ground!