Both materials have a long history in RC undercarriages, and both still have their place — the right choice depends on what you fly and how you fly it.
Aluminium gear has been the traditional default for decades. It’s forgiving, relatively cheap to produce, and it fails predictably — a hard landing tends to bend it rather than snap it, which some flyers actually prefer because a bent leg is a visible warning sign, and often can be bent back into rough shape in a pinch.
Carbon fibre gear is lighter for a given stiffness, which matters most on 3D and aerobatic scale models where every gram affects the power-to-weight ratio and where a stiffer leg means less energy absorbed as unwanted flex during hard 3D landings and torque rolls. The trade-off is that carbon doesn’t bend and re-use the way aluminium does — under enough stress it will crack or delaminate rather than deform, so inspection after a heavy landing is more important.
Neither is objectively “better” — a sport pilot flying smooth grass strips off a 50cc Yak may never stress aluminium gear enough to notice the difference, while a competition 3D flyer landing hard and often will feel the benefit of carbon’s stiffness immediately.
If you’re upgrading rather than replacing like-for-like, it’s worth checking your model’s designed all-up weight against the gear’s rated range — going carbon on an overweight model won’t fix a fundamental mismatch between weight and leg stiffness.
You can browse our Carbon Undercarriage for 30 size nitro / electric sized RC models to see this in practice.