I did my first full Tri a year ago last September and know I will need to replace my Bike. It is an old Mountain Bike 26 inch wheel. Would like some help in getting a bike for not only racing, but also it will be used for commuting.
Hi and welcome to CC. FYI I'm 6' 5" with a 35 ish inside leg.
In recent years I've had bikes ranging from 60cm to 65cm frame size, basically IME I find the older the bike the bigger it needs to be.
I currently ride a Cannondale CAAD10 with a 60cm frame, and it's spot on for me. I've since changed the stem, bars and seatpost, but TBH I've not changed from the original sizes.
A lot is down to where your height is as well, what I mean is I'm quite evenly proportioned for my height, whereas someone else may have really long legs or be really long in their body.
Also, different manufacturers offerings will feel different even with the supposed same size frame, so again try as many as you can, although Cannondale frames do tend to be a touch longer in their top tube, hence my 60 is OK for me whereas a 60cm Giant or Spesh would probably feel too small.
What I would say is being tall try to stick to traditional geometry rather than compact geometry, although it is of course upto you. Traditional means the top tube is more or less straight, whereas the modern trend for compact geometry gives you the sloping top tube, this makes the bike look smaller overall, and when your tall that's not a good look IMO, but I just don't like compacts myself anyway TBH.
TRADITIONAL 
COMPACT 
The
RIBBLE that Hacienda mentioned above is a great all round bike IME, and starting from £550 won't break the bank. I've had a couple myself and TBH they out number everything else massively on the roads around here once the weather turns, so if your happy with alu give them a look, or if you want a
plastic carbon frame then look elsewhere.
FWIW the
CAAD10 is 'only' an aluminium frame, but it will puch your budget to around £1200 - £1500 for the 105 version, although there are some bargains to be had. I got my CAAD10 as I wanted a high end bike but was fed up with carbon fibre, and it's the best decision I ever made. Just remember, carbon fibre is not an upgrade alu, it's just another frame building material which may or may not be the right choice for you.
Good luck, wish I was in the market for a new bike myself, never to replace the CAAD, just to compliment it
