Fi, just had a quick look at try a tri Cardiff and this is a 400m pool swim, 16k bike and 4.5k run, which is pretty much the same distances as a super sprint which I do as I'm not keen on open water swimming.
Not too sure but I'm guessing that these events are for notices only so you won't get the super stars with their fancy all singing all dancing TT bikes making you feel sub standard. I would think that the set up would be the same as a normal tri where you can wear a tri suit if you wish but most will wear just a normal swim trunks/costume and then add shorts, test, socks etc in the first transition before the bike. Hope this helps, any more questions feel free to ask, I'd say give it a go, I'm sure you'll enjoy it. Oh, and one more thing, don't panic if you don't have a fancy bike, I've seen plenty doing tri's on mountain bikes and even shopper bikes.
