Asthma

Just to add, the symptoms are not that drastic most of the time. In my case pretty much regardless of how fit I am I'm slower than my friends up hills, which is a symptom:

It might be expected that people with E.I.B. would present with shortness of breath, and/or an elevated respiratory rate and wheezing, consistent with an asthma attack. However, many will present with decreased stamina, or difficulty in recovering from exertion compared to team members, or paroxysmal coughing from an irritable airway.

Hooray, I'm not just a lazy sack of shit - I now have a medical condition to blame.

The wheezing and shortness of breath do happen for me but only very rarely. When I do get wheezy it's bad enough that I have to sit down for 10 minutes, but that usually only happens if I start a ride by going up a big hill when it's really cold.

Also the prevalence is quite high amongst athletes (it's 8% in general population IIRC):

“Athletes are far more prone to asthma-related problems, mainly because of the environments they’re exposed to and the conditions required by the sport, such as the high breathing rates over prolonged periods.

“Cycling is done outdoors, often in dry, polluted air — there are lots of reasons for the high prevalence.”

Given that amateur riders are exposed to as many asthma-triggering factors as the pros perhaps even more in some cases, e.g. urban commuters breathing polluted air — we are just as likely to develop symptoms.

Does this mean that all of us should get tested? “Yes,” says Dickinson, “when we work with squads of elite athletes, we test everybody — it clears up any doubt.”

If you have some of these symptoms maybe worth getting it tested.