I’m a cyclist that recently got roped into doing my first Ironman. Thankfully the event is in 2020, so I have lots of time to get my head around this.
My question is around kit, what are the essentials I will not be able to go without for the event?
Wetsuit or Trisuit??
Will my road bike do the job???
What shoes are best???
Any guidance will be most welcome!
Shoes for what? Bike or running? Either way, those are personal preferences. Bike use what you know works now.
Plan on doing small ones to learn the ropes early. Get a couple of sprints in this summer at least.
After reading my first post I realised I was a bit sketchy!
Running shoes, I’m quite comfy with my cycling ones.
If you go to a local running shop, they should do a quick fit/analysis and find a shoe that’s likely to work for you (at least for starters). They’ll put you on a treadmill, look at your stride in slow motion, and say “you probably need a shoe with more/less support. here are three to try on”
@aldenhart hit it. Like cycling shoes, you have to try them on. I ended up going to Hoka shoes for road runs as my others did not feel right. I don’t recall what brand my trail shoes are (I do Xterras) but they work pretty well.
Try a couple of different stores for different brands. I really like the Hoka 30 day trial – they tell you to run in them and if you don’t like them, they will take them back.
What is the expected temperature at your race? If the water temperature is above 76.1 degrees Fahrenheit (24.5 degrees Celsius) wetsuits are prohibited anyway which takes that decision away. If you can wear a wetsuit, are able to afford one (a cheap one will do) and can train with one I would recommend it unless you are an excellent swimmer and already know you’re better without one. I find it’s a bit more taxing on the shoulders to swim in one but the additional buoyancy is a god send if you have sinky legs like me 
Where I am we have a few wetsuit mandatory races and others where the water temperature is low enough to often make them mandatory. I don’t think that’s usually the case with IM branded events everywhere though…
As to whether or not you should wear a trisuit; you’re doing a very long event which means that your transition times are less important than in a short race. You can put on full bib shorts for the bike and running shorts for the run (so long as you are not publicly naked while changing = disqualification) if you want to prioritise comfort. Do you get a changing tent, or are you allowed a towel/dryrobe in transition?
To echo the others about the running shoes; nothing is better than spending time in shoe shops and figuring out what works for you through discussion and testing.
you can rent wetsuits as well. Try before you buy.
Having just gone through a similar situation (albeit not Ironman distance), here’s what I learned:
I was just fine swimming in a sleeved trisuit. However, the water was relatively warm (I’m in Hawaii) so your situation may be a bit different.
I ran my Santa Cruz Stigmata gravel bike with clip on aero bars that I got cheap on Ebay; it was perfect. No need to invest in a tri-bike if you’re not 100% sure you’re going to stick with it.
Running shoes are very much an individual preference. As others said, hit up your local running store and have them help you select what may work. FWIW, I rotate between Hoka’s and Altra’s.
Lastly, I absolutely recommend starting with a sprint distance triathlon. It was the perfect length for me when I did my first one. Not too much but definitely still felt like a solid accomplishment.
Good luck!
Just know most people pee in their wetsuit. I’d hope you wouldn’t in a rental but people are people…
Yea, like others said, clip on aerobars are something you really should do and a fast forward seatpost is also a good idea. Another good investment would be an aero helmet if you don’t already have one.
I’d say 10-25% of the field will have road bikes, so don’t worry about “looking out of place” either, and have fun!
You do realize the water you drink today could have remnants of pee from Alexander the Great or George Washington in it, right? Never mind looking at the condition of the water lines that bring water to your residence (you do NOT want to do that!). What about the pool?
Wetsuits wash.
Never mind … I have been in worse.
Getting started in triathlon by doing an Ironman isn’t a great approach, but do a local sprint tri first and see if you like it. Otherwise it could be months/years of suffering for an event you don’t even like…
Wetsuit? Yes
Trisuit? Yes, and/or tri shorts and top.
Road bike ok? Yes
Best shoes? Ones that fit
It’s a long journey but basically, you just need to swim a bit, bike a bit and run a bit. How hard could it be? 
Sorry missed this bit.
Almost all events require:
UK Ironman/Middle and Long Distance tri events almost always require wetsuits but your local sprint tri could be done in a pool.
Could??? It’s a mathematical certainty there’s millions of their former pee water molecules in my glass of water right now.
The pool, it doesn’t bug me that people pee away in there. Wetsuits are just different for me. I know they wash but so do underwear. And I personally I just wouldn’t put on used underwear no matter what kind of deal I was getting. But that’s just me.
Others have given their thoughts on equipment. I’d buy or rent a wetsuit if the race is going to have cool enough water. Depending on your goals, you might answer the road bike question. I’d recommend at least clip on aerobars and practicing with those. You’re going to be way more aero and more comfortable than holding your position otherwise.
Ironman is an eating contest. I think the single most important thing to plan, train, and practice is your fueling plan.