Advice on a bike

Am looking to set my new goal this year of competing in a half ironman (middle distance race...is that right?), anyway at the moment im cycling on a racing bike that was given to me and am now thinking its about time to step up a bit.......now having just done the london tri, in atrocious conditions i was amazed at the different kinds of bikes there were, it was like bike porn!!!!!  Firstly is there a need for a proper tri bike if im just doing the middle distance and also and most importantly ive a rough budget of about £600-700.  Any advice no matter what would be greatly received on what kind  and make of bike i should be considering,

You don't need a tri bike.
For the avoidance of doubt... You do not need a tri bike .

Most important is to get a road bike that fits you and is comfortable, which probably means paying over the odds to buy it from a real shop (rather than ebay/online) that has selling bikes as its core business (rather than Halfords). Some people will say "professional bike fit from your local bike shop", but my experience is that unless you go very top-end, they tell you no more than the numpties in Halfords and Ribble Cycles, so I'm not convinced that £70-£150 of your meagre budget's going to be well spent on one of those. At that price you should be able to get carbon forks, but you're not going to get a full carbon bike.

ty, i might actually try some local bike shops, am weary about ebay etc as im not quite sure of fitting heights etc.

Exactly. No point buying a "bargain" if you can't ride it. You need to be comfortable for your first half. Otherwise you'll end up shuffling a half-marathon like you've still got your saddle up your chuff.

I've bought two bikes from Evans and the guys there spend a good hour or so fitting it for me - perhaps not the best fit in the world, but it was free so good value for money!

i had the same experience at Evans. The guy i was dealing with spent ages with me on a turbo trainer setting up the seat position, organising the spacers to give me the right height on the bars, and ultimately recommending and fitting a shorter stem for me. I think it's about building a rapport with the person serving you and then they go the extra mile.

I will eventually pay to get a computer assisted bike fit done (eg. Retul) but will probably wait until I have pimped my bike next year first.

Shortround, my first bike for tri was a specialized allez- £600 new- carbon forks, aluminium frame etc. A really good bike for the price and served me well for over a year. You could go second hand and be in with a chance of carbon- a friend of mine got a Boardman for £600 and is well happy with it- not sure where he got it though.

I bought the Giant SCR3 I use most of the time from Tri UK when they were getting rid of all the previous season's hire bikes. One year old, decent condition and cost about £400.

I got my Boardman through the Cycle to Work scheme at work. Amazingly light but I only use it for sprint races where the terrain is reasonably flat.

Have seen the scott speedster s50 triples 2012 for £599,  Has anybody got any thought on this bike.  Looks good to me, but my bike knowledge is very limited

It was my first bike - very good overall. I loved it, and rode it for a bout a year until I got a bargain CR1

Go to  local bike shop and ask their advice, they (mostly) know what they're talking about. I kno wmy lbs will spend ages talking to people about what they want and their options with no  pressure to buy, and they do a proper bike fit for each customer.

i did my first half IM on a hybrid.......   Its doable, but you will be comfier / faster on a road bike

I did not buy a tri bike until IM season 3.......

I Love it, but its one hell of a commitment / money  pit, but more importantly, I have a road bike to train on when the weather is bad.