I had the Pfizer vaccine earlier this year. First shot I just had a mild headache the next day, second day I felt fine and rode 1/2 of what I usually would and felt fine after it. Second shot I felt kind of 'flush' all over the next day; it was something like when you start to get the regular flu, but it didn't progress any farther that that and no headache, body aches, or nausea. The second day I felt great and did a shortened ride with no problems. I haven't had any issues since then.
Co-workers and friends who have had the Moderna vaccine seem to have a more aggressive reactions than the Pfizer, some even getting a mild fever and nausea, but its usually just 1-2 days of taking it easy and they were back to normal. Those who had the J&J single dose have only had mild issues like I did with the pfizer vaccine.