SkepticalOne

I wouldn't consider the SLR to be worth the upgrade. My own preference would be disc over caliper first and invest in the items you already mentioned. One thing you haven't mentioned is saddle. In my case, I ended up ditching the Bontrager saddle that came with my SLR which meant another $150 for a Specialized Power Pro.

WhyFi

There are two main benefits to the SLR - weight (frame is made from slightly higher-spec carbon and bars, saddle, etc are a little better/lighter) and the adjustable Rear IsoSpeed. I'd rather put that price difference towards better wheels, but YMMV.

Campag4life

OK...will give you my take and others of course may disagree. Lots of disagreement about rim versus disc brakes for example.

So, lets start with brakes. Since you state that you ride mostly in flat land, I do as well, don't buy a disc brake bike unless you ride a lot in rain.
Disc brakes are great for long descents or descending in the rain but I find absolutely no need for disc brakes on the flats or rollers. Zero.

You are big boy and you don't race and you mostly ride on the flat. Weight of bike matters a bit less truthfully, especially at your body weight.
A couple of lbs isn't going to matter riding the flats...or 5 lbs and also meaningless if you don't race. Take away? What WhyFi wrote. Don't get the SLR and money saved you can invest in wheels but honestly at your weight, you want wheel strength and not lightweight wheels. Truthfully, I am 180 lbs and unless I stumbled on a smoking deal on a SLR, it would be SL6 all day long. The slightly heavier frame 'may' in fact be stronger fractionally. The SL6 frame is still at a competitive weight of ~1000g or so. There has been conjecture that the SLR flirts with the edge of lightness at 'perhaps' some peril to fragility. 'Maybe' an issue for a big guy like you.

You have established you want an endurance geometry bike. Keep in mind, geometry varies a bit for the three bikes mentioned.

So what to get? I think you have found your bike. Domane SL6 Rim with Ultegra...about $3K. Great bike. Less hassle with rim brakes.

Tire size for your body weight of 225lbs? Wide. More comfy ride? See if the bike will fit 32mm wide rubber. Quite sure it will..but look into this for the rim brake version if interested in riding wider than 28mm wide tires.

Last comment is with respect to geometry. This is a bit nuanced but wanted to share. The Domane of all the endurance bikes on the market has one of the highest Stack/Reach ratios on the market. What does that mean? It means the bike is tall with shorter top tube i.e. higher handlebar relative to reach.

So how to navigate this geometry? Carefully of course as choice of bike size is super important because fit is everything.
At 6' you would likely be on a 58. But I am 6'1 and I would be at least on a 60 with 130mm stem. Reason is, the Domane has a short reach for a 58cm bike. I need or rather prefer a longer top tube. H2 Emonda geometry in fact works a bit better for me. But if I size UP on the Domane, I can get it to fit in reach, but it will have a monster head tube I can tame my lack of spacer stack and stem negative rise if necessary.

But you may prefer a shorter top tube and ride a bit more upright. You maybe perfect on a 58. Also depends on your body proportions. Many heavier muscled riders have a shorter inseam and that means longer torso for their height. For these riders, they may need a longer top tube and of course don't need a taller bike because of their short legs.

Only want to point this out. Choose your bike size carefully. Hope that helps.

noodle soup

4 months ago I would have said the same thing, but after 3500 mile on a disc brake bike, I no longer fully agree.

I didn't want disc brakes, because of the reasons you noted, but when my bike was stolen in April I found a great deal on a Domane 6.9 disc(9070 Dura-Ace). The difference in braking performance/effort is huge. I rode my backup bike last week(6800 Ultegra), and couldn't believe the amount of effort required. It never bothered me before, but I doubt I'll buy another rim brake bike, unless its for TTs only.

FTR, I chose the Domane because the frame dimensions are nearly identical to the custom frameset it replaced, but the seat tube design makes the ride far smoother than any CF bike I've ever ridden.

Campag4life

Honestly, where I ride, I almost never touch the brakes. Last thing I think about. My opinion is, environment matters when choosing brakes.
Guys I ride with are pretty much all on rim brakes and we don't like to ride with guys who hit their brakes hard.
If riding big hills or mountains, brakes to me matter much more...or riding a lot in the rain.

noodle soup

I agree 100%.

Having strong brakes, doesn't mean you have to hit'em hard. All it means is that you don't need to use as much effort for normal braking.

Modulation is key, and discs win hands down.

carlton

Werner,

I test rode all the bikes you listed plus the Diverge. I liked the tall stack and low bottom bracket of the Roubaix and the Diverge they put me in a more upright riding position which I prefer due to lower neck issues. The synapase is a bit more laid down than the previous two and wasn't as comfy for me. I wanted to run wider tires for additional comfort so the Diverge won out over the Roubaix. I then tried the Domane it immediately felt more comfortable than the Roubaix or Synapase . Comfort wise it felt about the same as the Diverge. Speed wise it felt much livelier. I mostly ride on pavement all though most of it is pretty crappy and I ended up going with the Domane. If I was riding a lot more on gravel I might have gone with the Diverge. I ended up putting 700X35 compass tires on my bike which increased comfort even more, with no loss in speed. I tried to fit 700X38 compass tires but they would not fit (to tall). All the bikes previously discussed were aluminum frame models except the Roubaix which was one of their cheaper carbon bikes. My Domane is the ALR5 DISC model. Carbon Fibre models in the domane were not available for me to test and a little over my budget. I can only imagine how much smoother they might ride due to their front and rear isospeed versus my rear only isospeed. I have over a thousand miles on my bike since I bought it about three months ago and am really happy with it. You can't go wrong with any of the bikes you listed.Somewhere on the interweb I read " Buy the one that fits the best, looks the coolest, and fits your budget".Thought it was good advice so I'll pas it along. Dealer service is not to be overlooked in your decision either.

dwolsten

I have a 2018 Roubaix Comp. The FutureShock works great, and it's really just a simple spring so I don't know what all the fuss about maintenance is about; it reminds me of all the old-timers screaming about how disc brakes need so much maintenance when they actually don't. I test-rode the price-comparable Domane (both bikes were carbon fibre) and it honestly felt sluggish and not very stiff compared to the Roubaix. With mine, the I don't even notice the FutureShock unless I pay attention to it; it soaks up the bumps and road buzz, but since it's only compliant in a single axis, the handling is still razor-sharp and it still feels like a very stiff racing bike.

You'll probably be very happy with any of those bikes really, but my vote goes to the Roubaix.

Campag4life

In bold above...point of clarity when comparing all the bikes for geometry...racy to most upright:
- Synapse is most racy i.e. has longest top tube relative to stack height
- Roubaix and Diverge have close to the same stack to reach ratio...which btw is quite upright as you note.

- But, Domane wins the upright prize if there is such a thing. This is a bit obscured if you go purely by the number on the frame denoting size. A 60 Domane has a shorter top tube than a 58 Roubaix. So, one has to be careful which btw is always the case when choosing frame size. Bikes today aren't squarely proportioned as in years past which is a good thing but places a bit more onus on the consumer to determine what best geometry is for them. If you want to be an informed consumer, one much look at the stack and reach of a given frame. A 60 Domane has both a shorter top tube and a taller stack than a 58 Roubaix. Geometry matters when choosing a bike of course and many believe fit on the bike is the most important thing.

But important to know that even though three or four bikes discussed, Diverge I believe is classified technically as a gravel bike but it really is a Roubaix with greater tire clearance...about the same geometry.

For those bike shopping, I hope above helps. I believe of all the endurance bikes in the industry, the Domane has the highest stack relative to reach in the industry. A footnote is...consider how overwhelmingly popular the Domane is here. Takeaway is, average riders love a tall stack with high handlebar and a shorter reach. Of course there will be those that prefer the stack/reach of the Synapse or Roubaix to the Domane as well.

Dean V

I am sure you could get the same "fit" on all those frames. With the range of stem lengths, angles, spacers available there is a lot of adjustability before it gets to the stage of giving weird handling etc.

Campag4life

Suffice to say there is variety of fit among the three bikes discussed and yes, with spacers and/or riser stem or not, can get it pretty close between the bikes so true.
For those shopping, point is the frame size no. on the frame may not be the same for each bike for a given rider for closest fit between the bikes.
Sta also affect net reach to the bars so top tube lengh should be considered in conjunction with sta.

bikebreak

I rented the new Roubaix (lower end Sport model) for a week and really liked it, I would say it's ideal for rougher roads. I went up some mountain roads that were not well maintained, and some dirt roads. see pictures:
https://www.strava.com/activities/1776647688

The future shock is fairly heavy, so if I was riding 99% on good roads I wouldn't bother and would get something lighter.

werner

zippifish

Congrats on the new ride.

WhyFi

Sweet - enjoy the ride and post up some pics when you get a chance.

avmech