is a carbon bike really better than aluminum?

is it better? prob not, however after riding both materials I must say carbon is more comfortable to ride (doesn't vibarte as much although some might think of it as a downside )  and in many cases stiffer hence you can transfer power better.

Now when you are in a budget you have to go with the best option that suits your needs. IMO Ultegra vs DA components is not that big of a deal. I mean DA are nice and lighter but the difference between those isn't THAT noticeable. In terms of aerodynamics it seems the P2C is definetly better than the P2SL, it prob won't be huge/noticeable difference since the engine is the biggest factor but free speed is always nice. Both are durable materials although it seems when carbon frames fail they do worst than aluminum plus depending on the fail type, aluminun *might* be fixable while carbon it is unlikely so that could be a plus.

Since I began Tri-ing I've gone with what my budget allowed me. Started with cheap entry level road giant, moved to cheap road giant with better componets, then moved to carbon road giant (race with this and clipons for a while) then moved to aluminum tri bike (got a cheap frame deal) and just until last week I moved to a cool carbon tribike. I always wanted to have a better tri-bike but had to go with $$ and I figured working on the engine was more important at the time (still is of course). That's all I have...

yes, I'm thinking I will LIKE riding the carbon bike more, but this one definitely will be insured.  I'd be afraid to take the carbon one on a plane though too, considering my bike's frame has been torqued. 

 I gotta tell you, my aluminum bike withstood going under a roof....the bike survived, the roof rack did not.   its definitely durable!

so how about comfort? I got NO power....I'd like to enjoy riding more.  less saddle sores would be nice, would I be less "tired" riding 100 miles on a carbon vs. aly? 

The difference between the UT and DA derailers is about 5 business cards in weight. Go pick 5 business cards up. That worth 300ish to you? 

The older dual is awesome enough that you'd be upgrading in fractions. (Old duals have better wheels/aerobars than the new P2SL). If you write "I'm poor", going from a pretty awesome tri bike to a slightly more awesome tri bike for 1000 makes no financial sense at all. If you have money burning holes in your pocket that's something else entirely.

I love my bike, but alas, I think it has irrepairable shifting issues.  This is not a "I want a bike", this is "I need a bike".  I CAN afford either, if I forgo some races next year...I'm thinking long term.  its not the components so much as the actual comparison between a carbon bike and an aluminum one with better components...which is more comfortable.  Therein lies the more difficult question.   

it does if the frame is bent.  I've already put on two new derailleurs and now new shifters, plus had the frame "rebent".   

I compared several bikes before buying.  I'm certainly no expert, but I ended up going with aluminum frame, carbon fork and seat post.  I don't feel a lot of vibration.  But if I had more money, I would have bought the all carbon bike.

Oh, and by the way, you are not poor.  I was in North Korea a few weeks ago.  THEY'RE poor.

You are getting tons of great input here.  I'd like to chip in my two cents.

In the past two seasons, I have owned three tri bikes.

The first one was a poor fitting Felt S25.  All Aluminum.  It was too big.  I averaged about 17.5-18 mph on this bike.  I rode it, and loved going fast, but it was a harsh ride that became uncomfortable after just a half hour.  An hour long ride was just about unthinkable.  It had top of the line components.  DA all over.

I bought a Trek Aluminum frame that fit me.  I swapped over the drivetrain from the felt, and this one had a carbon seatpost.  All of a sudden, riding became more fun, and MUCH faster.  I was able to average 20mph for the first time in a race, and I could ride it for over an hour without too much pain.  I always felt whipped when I was done though.  Some of the harsh vibration was still there.

Then, just recently a very fast young lady who posted above me in this thread, pointed me to a deal that I could not refuse on a P2C Ultegra.   I snapped it up and have been riding it for just a couple weeks now.  I had hoped that I would get rid of the harsh vibrations and get a great fitting bike that I could ride all day long.  My initial opinion is that I got exactly what I wanted.  Now, my training rides are much longer in time and distance, and faster.  I think the speed is coming from comfort, not the weight savings, by the way.

So, yes, I think carbon is better than AL, simply for the comfort that I have gained.  Both of the last two bikes were FIST fitted, and we took the measurements for the P2C, directly off the trek.  I don't care much about weight savings.  I'm not sure how much a difference it makes to me.  But, I do know that the buttery smooth ride that I get now, allows me to go faster with more comfort than I have ever experienced in the past.

One last thing.  I feel very firmly that a very well tuned Ultegra drivetrain is WAY better than even a moderately tuned DA drivetrain.  If you can dial in your Ultegra system, use it.  They are excellent components.

The P2SL is a whopping 100 grams heavier than the P2C; if weight is the deciding factor, I'd opt to just visit the restroom before going out on a ride - I can lose 100 grams on the crapper and it doesn't cost me a dime.

Comparing comfort, stiffness, power transfer, weight, etc between aluminium and carbon is still pretty subjective between individual riders and some generalizations can be downright misleading, such as aluminium being stiffer and carbon giving a more 'comfortable' ride. Varies betweeen manufacturer, model, frame size, rider fit, weight, the way the planets line up and if you hang right or left.

In answer to the original question, first I'd make sure I rode both and could be fit on both, but I'd still lean towards the P2SL and race wheels.

I agree to a degree with Sty. My first "better" road bike after getting back in and riding my 24 year old steel frame was(and still is) a Carbon TCR w/ Ultegra. I will never go to aluminum for my road bike as I love the dead road feel of the carbon frame. I'm in fact upgrading from my TCR Ltd to a TMobile TCR Formula1 frame which weighs 1.75 lbs and is much MUCH stiffer than my current frame.

My TT bike is a Guru Trilite, aluminum frame w/ carbon forks, stays and seatpost. My longest ride to date on the Guru is a bit over two hours but I felt comfortable. However I do feel every bump and pebble on the road...

That having been said I have friends who ride Alum bikes for hours on end while I'm on my carbon frame and they are fine...

Its a very subjective deal...

Eric J

x1,000,000   

THANK YOU.  first really helpful comment and of course from a girl.