Basic checklist:Tri suit or swimsuit + clothesGoggles (plus a spare if you have one)Wetsuit (if using)Bike with roadside repair kit (spare tube, air cartridge and tools)Helmet + sunglassesBike shoes (if using)Running shoesRace belt (optional but handy)Sports Watch (if using)Bike Computer (if using)Nutrition + electrolytesTowel, body glide, sunscreenID (often at larger races, goverment issue picture ID is required at registration)And bring a calm brain, transitions feel hectic only the first time or two.