a snowmobile frame is described , with a tunnel having an inverted u - shape . an engine cradle is attached to a forward portion of the tunnel . a suspension assembly is disposed forwardly of the engine cradle . at least one support member supports the suspension assembly on the engine cradle . the at least one support member forms a crumple zone between the suspension assembly and the engine cradle . the at least one support member resists plastic deformation in response to the first predetermined force exerted on the suspension assembly . the at least one support member undergoes plastic deformation in response to a second predetermined force being exerted on the suspension assembly . the second predetermined force is greater in magnitude than the first predetermined force . the tunnel resists plastic deformation in response to the second predetermined force .