Although most modern bikepacking kit is designed to attach onto the frame directly, touring bikes usually come with traditional rack mounts both at the front on the fork and at the rear on the stays. This is to maximise luggage-carrying capacity without putting undue stress on the frame.
Since these bikes are designed to carry camping gear - extra clothes, a tent and sleeping bag etc. - that means extra weight to lug up hills, so lower gears are provided to help, with cassettes usually featuring a 32-tooth sprocket, or even larger. Standard compact 50/34 chainsets are typical, but 1X groupsets (with a single chainring) are increasingly common, paired with a very wide-ranging cassette (eg 11-40).
Wider tyres improve comfort and grip on poor road surfaces and trails, so you can expect anything from 35mm up to a super-wide 50mm. Tread patterns sit somewhere between fully slick road tyres and knobbly MTB tyres, which provides a good compromise for riding on mixed surfaces. Like with a lot of disciplines of cycling, tubeless tyres are becoming more and more popular, allowing you to run lower pressures for improved comfort, and containing sealant that instantly plugs small punctures.
Steel is the favoured material because it offers strength and comfort, and is relatively cheap to produce. Titanium is a lighter option for those with deeper pockets, while carbon-framed adventure bikes are available for those who don’t mind forgoing rack mounts. Geometry-wise, expect a long wheelbase (over 1m, even on medium-size frames), deep bottom bracket drop and shallow head angle, for stable handling even when fully loaded. There will also be generous clearance for fat tyres and mudguards.
With bikepacking, reliability is key, so strength and comfort comes above lower weight. Wheels are normally configured with up to 32 spokes, which increase durability when riding over rough terrain. It also means the wheel is more likely to remain rideable even if a spoke breaks in the middle of nowhere, miles from the nearest bike shop.