squatchy

I think I can chime in here. I actually own both bikes. Both are S-Works. Both have dimensions that are the same even though one is a 58cm and the other is a 61cm. For what ever it's worth I'm a clyde 6'3" 250lbs. I ride around 5k a year and spend time on both bikes every week of the year. Both have the same saddle, neither have the CG seat post.

Both bikes are great bikes. Nothing left to desire in either bike. Both roll up nicely, are equally as fast as far as I can tell. When I first started riding the Tarmac (was purchased after the Roubaix) I found for the first few minuets I would over steer a bit in sharpish curves. Now that I think about it I don't ever do that any more.

While the Roubaix is by no means sluggish I would say it is just the slightest bit more "casual" in steering response. I may have thought initially, that the Tarmac had a bit faster hole shot. I also may have thought it was just the tiniest bit faster. Once I bought a second wheelset to match the very fine wheelset I have on my Roubaix, I then realized the fraction of a difference disappeared with like wheel sets. Hed Belgiums with DT Swiss 240's. The Tarmac is just a taste faster in steering response and weight shifting. Some use the word "twitchy". That word is fine as long as you don't read anything negative into it. That is why I choose "casual" in what I wrote earlier.

After now owning both for some time I can say this without reserve. The only real difference I can tell is that in longer rides, 100 miles or more, I feel the road fatigue sooner on my Tarmac. If I were to quantify it I would say that maybe 70 miles on the Tarmac seems like 110 on my Roubaix. Anything under that and I doubt I would notice any difference in regards to "road rash"

I would seriously doubt anyone could prove to me that a Tarmac is faster than a Roubaix unless they were in a wind tunnel. I have my cokpits set up the eaxct same so I don't get ant "aero" benifits from the Tarmac.

Lastly mine are both SL3. My friend has ridden both my bikes for a very long time trying to decide what of the 2 bikes he wanted to buy. He ended up getting a new S-Works Roubaix. Against my recommendation he purchased a SL4. I have ridden it many times and feel (along with others in different threads here) that the SL4 is too stiff.

Specialized say the CG seat post is part of the SL4 set up. I have yet to ever see a GC in real person and the last I knew they are not for sale yet. Perhaps with that seat post it would take away some of the harshness from the SL4. I wouldn't trade my bike for his even if there was money involved. I think they went too far towards stiff on the SL4

Hope that helps

RollCNY

Squatchy, it is funny you have a 58 and 61, as that is exactly what I would have needed as well. The 58 Tarmac just felt crowded.

And OP, I actually need to thank you. I have been waffling for a week about building up a steel bike or buying an all built up carbon bike. Talking about my test rides reminded me of how nice my Nashbar alum / carbon stay bike rode, so I have dug up the frame, and I think I'll order up some wheels and a mixed Centaur / Veloce group and get her back on the road.

Roobay_today

I'm Thinking of just buying a frame and building. I think it will cost more up front, yet it will be less in the long. The only thing stopping me is I might run out of money for the bike, And I would like to have it for the ms150 in April.

Dunbar

I hope you're wrong, but I fear you may right about this. Specialized warranty is replacing my SL2 Roubaix frame with a 2014 SL4 Roubaix Expert. I spent 3 weeks on SL4 Expert Roubaix loaner bike and it definitely felt substantially stiffer over rough pavement. It had the stock wheels and Roubaix Pro tires on it which don't ride as well as GP4000s tires. I'm hoping with my wheels/tires the ride will improve. I wasn't about to turn down a free upgrade to a $3k frame though. Worst case I guess I install one of those CG-R posts...

RollCNY

It may or may not be more expensive. If you have specific tastes, and start swapping parts into a fully built bike, you can get upside down in a hurry.

I hate the wheels that come on most low to mid level stock bikes, and know that I will replace them. Between that and saddle (I like the Romin saddle), I can usually build cheaper than buying.

Also, a lot hinges on the frame you buy. If you are planning to pick up a new frame with warranty, building from scratch is less competitive.

Dunbar

Especially with the current Specialized frame pricing. The Roubaix SL4 Pro frame lists for $2950. You can get a complete bike with that same frame and Ultegra 6800 for $3800. Building can make sense if you already have parts laying around. I think the SL3 frames were priced a lot more reasonably.

dgarzoli

ive ridden a sl3 tarmac and roubaix back to back mid long ride and to me the ride qaulity was nite and day. the tarmac felt like i was riding a 2x12 turned on its side and the roubaix felt like a full suspension mtb. I have another friend who rides an sworks tarmac sl3. we are remarkably close in fitness and strenght and trqde wins back and forth every ride, so i know the roubaix is every bit as fast as a tarmqc. my .02

Long Tom

Put me in the camp that says a 3-mile urban ride isn't a valid test of the two platforms- although I'd be all over the same test rides, don't get me wrong, if that was available.

I'd expect a Tarmac to feel snappier, but at least for ME, speed is fairly irrelevant. I do long rides, usually solo, and it's comfort uber alles. But that's ME. The extra snap from the Tarmac might light a fire under you and if so, that's a great thing.

I'm just looking forward to that laterally stiff yet vertically compliant ride yadda yadda yadda. Insert tongue in cheek emoticon.