I'm bridging up to my 1st Oly next weekend, but I'm your inverse sport-wise
(avid cyclist, weak runner
). As strong as you are running & swimming, and knowing about hydration/fueling/pacing from marathons, I bet you'll be fine. Just get in some saddle time on the bike
(even just 5-10m rides 3-4x/wk
) over the next 4 weeks to harden up the sit bones & feel more comfortable riding
(pedaling, shifting, braking, bike handling at speed
). Concentrate on staying relaxed & spinning
(not mashing
) the pedals at around 85-90 rpm. Do a few simple short bricks
(15-20min bike-run sessions
) to get the legs used to that bike-to-run transition. Get the legs loose on the last 1/2mi or so of the ride- Spin easy gears a little quicker, and stretch the calves a little during pedal stroke. Might start your run a little easier to settle in to your stride. During the event- don't forget to hydrate/fuel early on the bike to recharge a bit from the swim.
As a new cyclist you might learn to change a flat tire & do basic function checks on your bike. Some bike shops have intro maint classes, or a friend could help you out. Most Oly events have some bike support on the course, although it might take 'em a few minutes to get to you. Never hurts to be as self-sufficient as you can.
Be confident that you're prob in better overall shape than most doing their 1st Oly
(myself included
).
Go for it & have fun!!!