Welcome to Healing Well! I'm so sorry to hear you're having esophageal spasms...no fun at all. There are several members here who've had experience with them, but I'm not one of them. To me it sounds like a positioning issue...bike racing requires you to lean forward, pushing on your stomach, and lowering the opportunity for gravity to keep the contents of your stomach where they belong. When acid migrates into the esophagus it can cause all kinds of problems. The delicate tissue (unlike the stomach) is not made to handle the acid.
I hope you find a solution very soon,