If you're swallowing bugs while cycling that means you're probably mouth breathing. It's pretty challenging to convert to strict nasal breathing, but it's worth it and a side benefit is bugs aren't a big deal if you're wearing something on your eyes.
In case people thought mouthbreather is just an insult, it can cause serious medical problems and even change the structure of your face. There are videos about it on the internet, with dramatic before and after photos (in both directions).
I cycle at the higher end of my aerobic threshold to get around and my bike is single speed so I have to go anaerobic on hills. Do you cycle at a more leisurely pace or do you maintain constant nose breathing even during strenuous exercise? If the latter, I would probably caution you of the health effects of that too.
I'm definitely curious if you have references to negative health effects of nasal breathing. I've seen quite a bit on the positives, even with strenuous exercise. I maintain nasal breathing when riding fast, during kettlebell workouts, and sandbag workouts.
Or it may just mean he is cycling fast. It is only when cycling st a relatively comfortable pace that you can get enough oxygen through only your nose.
