Most modern carbon fibre landing gear is designed for bolt-on fitting, but epoxy bonding still comes up, particularly on scratch-builds or older-style airframes, and it’s worth understanding when each is appropriate.
Bolt-on is the standard for good reason. It’s inspectable (you can remove the gear and check both the leg and the mounting area independently), replaceable without damaging the airframe, and it distributes load through a small number of well-defined points that can be individually torqued and checked (see Day 17). For the vast majority of models, if the gear and airframe are designed for bolt-on mounting, there’s little reason to deviate from it.
Epoxy bonding has a place, but it’s a less forgiving choice. It’s occasionally used where an airframe genuinely doesn’t have a practical bolt-on mounting point, or as a supplementary reinforcement alongside bolts rather than as the sole fixing method. The major drawback is that a bonded joint can’t be inspected the way a bolted one can — any developing weakness in the bond line is essentially invisible until it fails.
If you do need to bond gear in, surface preparation is everything. Carbon fibre needs to be properly abraded and cleaned (not just wiped) for a structural epoxy bond to have any chance of matching the strength of a well-executed bolted joint, and a two-part structural epoxy rated for the loads involved is essential — general-purpose hobby epoxy is not the right product for a load-bearing landing gear bond.
When genuinely unsure which method your specific gear and airframe combination calls for, bolt-on is almost always the safer default if the airframe can be adapted to accept it — the inspectability and replaceability advantages are significant enough that it’s worth some extra effort to achieve a proper bolted mounting rather than defaulting to bonding for convenience.
Our Carbon Fibre undercarriage for 50e and 50 size nitro is a good illustration of the kind of fit and finish to look for.