Beginner bike choice between Defy and TCR.

The Defy will be a bit more versatile; with wider range gearing, ability to have a higher position for less neck strain, and probably accept a little bigger rubber.  No downsides really.  But it would be good to ride both to see what you think- although things like saddle positioning (fore/aft) and stem lenght can make BIG difference in how the bike feels to you.    The bikes should be set up approximately the same for you to make an informed decisionneed to be set uphow the bike is set up   

Re: wanting carbon rather than aluminum- if you can find a nice aluminum frame there is not too much difference in ride quality.   I have a high end carbon Trek, and Trek's aluminum ALR.  Hard for me to tell the difference.  Any ride quality difference can be offset by lowering tire pressure by 5 pounds.    If you can get a high quality aluminum frame (such as offered by Cannondale, Trek and Specialized) for significantly less than a comparably equiped carbon frame; that would be the way I'd go.   The good aluminum frames are about a half- 3/4 pound heavier than a  nice carbon frame (I define nice as frames found on bikes in 3-5 thousand dollar range.  not top of line, close to the top of line carbon frame of that company).

The reason I would choose the nice aluminum frame over the carbon frame, is to save my budget for  better wheels- or a spare set. 

Wheels are something to consider upgrading, if you want to spend more money, since many bikes will neglect the wheel spec to keep costs down .   A rather inexpensive upgrade is a good aluminum clincher (such as Fulcrum Quattro Pros which can be found for $300-400).  or for $1,300 or less you can get pretty nice aero (40-45mm deep) carbon wheels such as Bontrager Auras or Mavic Cosmic Pro Carbons.  

Good luck

As you may have seen from the pictures of my bike the first bike in recent years was a Defy 5, it was all I could afford at the time and is a great bike for a first bike, great endurance geometry. Have done loads of Sportives on it both metric and imperial centuries. I would recommend it to any one. I found that I was able to keep up with most folks on it as it's not the bike that holds you back but yourself, ie fitness. I often was able to keep up and leave behind people on much more exotic bikes, I was even able to do this on my lump of a down hill mountain bike much to the chargrin of the guy on the carbon everything bike. :). Yes now I have a carbon bike of my own a Ridley C60 and very happy with it too, but I'm glad I waited until my engine got a whole lot better and I feel I can do the bike justice, still need to work on my climbing though.

Maybe, although if you are slower than your friends or struggle on a Sportive you will blame the bike! A bike with space for 28mm tyres is the answer if you go down that route. I have a Genesis CdA 10 which is my winter hack but would be OK as a Summer bike with mudguards off and smooth 28mm tyres. May well use it for Devon coast to coast this Summer. Good luck, you should develop affinity for your new bike, there is a huge choice of good bikes above the absolute bargain basement. 

I had a specialized dealer near me so I went there for my first road bike. My dilemma was the same, but I was looking at aluminium entry level bikes. It was the Allez, which has more TCR-like geometry and is similar to the Tarmac, or the Secteur, which is more like the Defy or the Roubaix.

I test rode the Secteur first as the guy in the shop knew it was my first roadbike after riding a hybrid for a couple of years (but I did ride roadbikes as a kid). I loved it, the road was smoothed out, it was super comfortable. It really is a good, supple ride.

Then I tested the Allez. As soon as I dug in I knew I had to have the Allez. It was so much more responsive and it felt alive. I still have it now 4 years later alongside my TCR.

When I came to buying a carbon bike it was a toss up between the bikes that were similar to the Allez as I knew that was the type of bike I wanted. Tarmac, Super Six or TCR. All were very similar and the Giant only won because of better service from the dealer. Very happy with both bikes and still ride the Allez loads as a winter bike, commute bike. The main reason I don't ride it more is because the TCR has a power meter so I need the TCR for anything training-wise.

Remember the pro's ride defys too, Degenkolb won Paris Roubaix on one, so you ought to be able to keep up with people on one. Looks like it had a fairly negative rise stem on it though.

Remember the pro's ride defys too, Degenkolb won Paris Roubaix on one, so you ought to be able to keep up with people on one. Looks like it had a fairly negative rise stem on it though.

I absolutely agree with part_robot. I wouldn't look to spend a lot on your first road bike, it is a major change from a mountain bike, so will all take some getting used to. 

If I look at my first road bikes and where I am now, I have made some major changes and refined my position over years. 

I like to earn a better bike, so tend to buy what is about right for my ability, upgrade as bits wear out and then progress to a new/better bike once I feel my ability deserves it.

I had a few ex-MTBer customers who had fantastic MTB's that had been refined over years of riding, who went to a road bike for much the same reasons as you, spent an amount of money that equated to a similar value as their best MTB, then found they just didn't enjoy it as much as MTBing and the bike either atrophied in the shed or got sold on.

I would look to a decent aluminium framed bike, see if you get bitten by the road bug and upgrade in a year or so once it becomes all you can think about (or is that just me?).

Just be careful not to conflate "this doesn't feel like it fits" with "I've not ridden a road bike much and I'm not accustomed to it". There will be a range of geometries that will suit you if set up correctly. It's hard to know this initially without a year or so of "growing into" a fit and learning what you want. You'll need to trust a fitter. For this reason I always recommend a riders first road bike be one that's relatively inexpensive.

All to do with hip flexibility I think, and you can only find that by a test ride.

There's also the Propel, which is beautiful and I only wish I could walk along holding my own kneecaps, then I might fit it

I have a tcr and it's a great bike but I probably wouldn't have thought that if it was the first bike I had bought! Would have been too aggresive. It encourages you to press on, stamp on the pedals uphill and attack everything! Yes it's about fit but it's unlikely you'd fit comfortably on a tcr without gradually developing your position into a more aggressive one over a period of time.

Defy has great reviews and would guess that's the one you'll feel more comfortable on. It can be made longer and lower as you get into it.

Ultimately they are both road bikes designed to be ridden fast and it neither will hold you back.

Giant shops are generally good IME and should let you test ride

Agreed. The fit should determine what you pick between the two.

As a road racing bike, the TCR is lower and longer. It will let you recruit more of your glutes and back muscles as you pedal, but whether or not you can sustain this position is the big question.

The Defy is shorter in reach and much more upright. Its popularity is deserved because it doesn't put undue stress on riders' backs, and is therefore friendlier for longer spells on the saddle.

Alternatively, if you want something that's in between the two geometries and can still give you a bit of off-road fun, perhaps the TCX cyclocross bike is for you. I have one from 2014, and I use it almost purely for road riding and commuting. Swap out the knobbies for 28 mm slicks and you get a not too shabby road bike.

Even if you go with the more upright Defy, you can always tweak the fit later on by lowering the stem. Granted, the TCR will have more scope for this, but that bike may also require you to get longer...which we generally can't do for road bike fit.

It all comes down to fit - if you read the reviews and posts on here and other sites and what feels right for you may not feel right for others.
I came from a similar background and ended up getting a cyclo cross bike first and the best piece of advice was try as many as you can. They all look great on paper but when I test rode some they were frankly a bit of a disappointment and that included some very nice bikes.
Hit your local Evans, LBS, Giant stores and test ride as many as you can. Evans have a great try before you buy policy and if you're around an average size have a good range to try without having to order stuff in. I'm pretty big and needed a 61cm frame but they still got me about 6 or 7 bikes in over a period to try.
Local Giant store is the same.
Plus you have some serious money so should get something frankly brilliant...
Also do your mates have any road bikes - I have a couple of really serious roadie neighbours who gave some great advice.
Sorry for long reply...