Good cycling pants can help to solve the hip pain in cycling.
Hips are an integral for cyclists and essentially need to be looked after as a joint that takes load all day, every day for most of us.
The first thing to outline in this article is the total myth of using hip flexors to pull up on the pedal upstroke. A wide range of articles have claimed that working on this upstroke power can create a more continuous effort throughout the pedal stroke and therefore lead to greater efficiency and overall power. It is now empirically proven in the literature that this is incorrect and will actually decrease efficiency and overall power significantly. (Please don’t do it!) The following studies utilised power meters and force analysis to prove that the lack of force seen on the upstroke is due to non-muscular forces, and consciously trying to pull up actually makes you more inefficient. (Martin and Brown 2009; Wadsworth and Weinrauch, 2019). The only exception to this rule would be a track start seen for initial deliverance of power in the velodrome.
One of the other major issues related to hip position on the bike, is saddle injuries. The saddle is an uncomfortable and rather crazy place to spend long hours in when you think about it. And then you need good cycling shorts.
A large amount of the seated position is point loading through the ischial tuberosities (bum bones). Pressure on the muscles in this area can cause soft tissue compression to the gluteal muscles, hamstring insertions and hip rotators, as well as to the posterior femoral cutaneous nerve and the male, and female genitalia (and also, the aforementioned vasculature).
Problems will normally occur when dramatically increasing the amount of time you spend in the saddle or changing your aero position aggressively and not progressively. Furthermore riding in the wet or gritty roads can cause increased skin irritation or possibly skin breakdown and infection (good and appropriate clothing helps dramatically here).
The bike fit you undertake can also cause these issues if altering too dramatically or in fact it is just incorrect. After this the saddle can be the cause, obviously if damaged or not straight (this is more common than you would think).
A correct saddle for you, can make cycling so much more comfortable, enjoyable and will make you faster.