How much slower would a cyclocross bike be on tarmac?

It really doesn't matter what tyre/bike combination you are going to use. If time of journey is critical leave a few minutes earlier. What is probably more important is the effort you're willing to put into your journey. A slower bike will give you a better workout. Then it brings into the equation do you need to arrive cool and unsweaty for work

As per the above, riding style etc. also plays a part.

My commuter is my road winter bike; a Specialized Gravel Bike 50/34 11/28 with 32mm slicks. My summer is a Specialized Allez 53/39 11/28 and 25 mm slicks.

On my summer bike I probably roll 3mph faster and will use less energy on a flat, probably slightly quicker off the line too. However, the winter bike isn't slow and some of my Strava PR's are on this bike (sometimes trying to get back before the light diminishes). I also spend much less time looking down, swerving potholes etc.

If you're looking for comfort and vibration dampening the quick wins are wider tyres at a lower psi and wrapping a second lot of bar tape on...

I commute on my Ridley X-Bow Cyclocross bike - It weighs pretty much bang on 10 Kilos. It has 28mm conti Four Seasons and 50-34 Chainrings, 11-28 Cassette. I have SKS Velo 42 mudgaurds that can both be removed in under a minute if its going to be a sunny week.

I can can do a pretty flat 10 mile commute anywhere between 17-19mph average on it.

When I take my Boardman road bike, which has fancy wheels, SRAM Rival, and Weighs about 7.8 Kilos, 25mm tyres, my speed is pretty much the same for this commute.

While the Ridley "loses out" in weight, it "gains" on its ability to be able  tocompletely "plough on through" on the commute, e.g. I'm able to cut corners, jump off kerbs, jump up kerbs, ride through rough grass and dirt patches of roads., without worrying about buckling any fancy wheels. Therefore, there is less stopping, and so my average speed doesnt drop.

The road bike is less effort and faster in a straight line, but... you have to watch out for all the road furniture, no way I can jump it off a kerb, I have to properly turn corners at junctions, etc, and truly stick to tarmac'd surfaces.

I can still keep up perfectly fine on a "club run" on my cyclocross bike, I might not be right at the front, but I wont get dropped at all, either.

For a commute, and winter club riding, the Cyclocross bike is an absolute blast. I would recommend one!

I ride a 2014 Giant TCX SLR 2. A cyclocross bike does not necessarily have to be more upright than a road bike; the TCX actually has a rather short head tube, and CyclingTips remarked in their review that its geometry isn't ideal for long-haul riding.

That said, among the bikes you mentioned, the Anyroad is the much more upright, slack option. If it looks like a cross-country mountain bike that sprouted drop handlebars, that's because it sort of is one in geometry.

Where I live, there really isn't much of a cyclocross scene - the word is foreign to most of my countrymen. I've found myself using the TCX primarily as a road bike, albeit one with beefy tubing and clearance for 35 mm rubber. Indeed, it came stock with 35 mm knobby mud tires.

As a road bike, the main limitations of the TCX are its gearing and its knobbies. 46x12 as a top gear will get you a maximum 48 km/h on the flats. The tire width isn't much of a problem; it actually helps with the rotten concrete and asphalt of Manila. The knobs introduce mid-corner squirm and ponderous steering, though. If you could get a lightly treaded 35 or 32 mm tire with minimal tread knobs, that would vastly improve mid-corner grip while retaining the capability to use the bike as a steam roller over bad surfaces.

Currently I'm using 28 mm slicks and I switched to a 50/34T crank and mid-cage rear derailleur. I don't see the need for any more road-specific modification unless I can get 30 or 32 mm road tires, preferably tubeless. At this point, it's only the overall bike weight that's slowing my TCX down: the stock wheels in particular are cross-country MTB refugees and rather heavy.

Markopic's right. A fat, slick tyre at 50psi is not slow on UK tarmac. When you hit rougher ground (tracks, cobbled streets, grassy fields) it's way quicker than a skinny tyre especially at 30-40psi. Also, wrapping old inner tubes under the bar tape might help with the pins and needles.

For a fast all weather commuter tyre the 28mm Conti GP4000S is one choice. They are huge! They appear more like a 32mm and would not look out of place on a CX bike. For a cushy luxurious alternative I would go with Grand Bois Cypres, Compass Bon Jon or Rivendell Jack Browns. Tan sidewalls . Mmmmmmm.........

I used to ride my PX Uncle John with a long, "slammed" stem and skinny tyres and it wasn't much different to a road bike I got later. Using knobbly 35mm Conti Cyclocross speed (small block) tyres has definitely slowed me down but they do look the part. I can also now cart my 3yr old son around on the back and take my daughter around moderate MTB trails. I can even partake in a CX race! I merely adjust tyre pressure as befits the occasion. Ultimately it's like riding in a Series III Land Rover. Slower, high driving position, and a bit quirky. Recommended.

Marathon Supreme ARE fast. But if you want getting towards road tyre rolling resistance then the Vittoria Hyper Voyager are a great choice.

I have three Dales. A Supersix, on 35mm wheels with 25c tyres. A SuperX in road mode it wears 28c 4 Seasons and has shallow rims. And a CAADX in road it wears 28c Vittoria Rubino and has shallow rims. 

The Supersix is fastest. The other two can be within a mile or so over an hour. 

The Supersix would be awful off road simply because of its tyres and brakes. 

The others are pretty versatile. 

It's all about the tyres. 35 mm tyres are slow, but the same bike with 100 psi 23 mm tyres will roll like a road bike. As far as the aerodynamics are concerned you can just bend your arms a bit more. 

Like somebody else said, "it depends", but in my experience, after tyres, geometry/setup makes a big difference. Much more so than weight. I have 2 race bikes with near identical geometry frames, both on slicks, one bike alloy with fairly relaxed setup, the other carbon, 3Kg lighter and aggressive setup, with the bars about 3 inches lower than the alloy bike. Living in Scotland, my rides are hilly and windy, and I too average around 18mph, with on average, 1mph (5%) difference between the carbon and alloy bikes. I'm a bit of a data geek, and scrutinise and compare every segment (need to get out more!). Much as we all like to brag about how our lightweight bikes "fly up the hills", the biggest time gain with the carbon bike is on the flat, and into wind. Cycling into the wind it is noticeably easier on the carbon bike due to its setup, just as on any bike it is noticeably easier on the drops than the hoods. So I could have achieved most of that 5% gain by dropping the bars on my alloy bike (saving £2.5k in the process)

Back to that "it depends" thing. If your commute is on the flat at a fairly steady 18mph, then you might not notice much difference. If it is hilly and the 18mph average is actually a 10-30mph range, then you will definitely notice a difference at speed. 

Whether you actually want to commute into a city with aggressive head down attitude? Well that's another question.

It'll be slower, for sure, but who cares? Cross bikes are f**kin awesome!

I used my Boardman CX on the road last year for many miles and found it great, once I changed the tyres. The weight made climbing slightly harder compared to my road bike, but not as much as you might imagine.

Best answer is: it depends. I think that difference in speed between road race and cx bike is certainly there, but it is difficult to judge how much it matters in real world. I have two bikes, one carbon with pretty much race geometry and Continental 28mm tires, other aluminium cx with Schwalbe marathon supreme 35mm tires. I commute around 20miles every day, and with both bikes I can manage that distance within 1-2 mins difference. On climbs with good road surface difference is maybe significant, but I can climb perfectly fine on cx bike. Also it is difficult to compare times directly due to weather conditions, head wind can be much more significant than difference between bikes. I have also noticed that cx bike with larger tires is much faster on poor road conditions than race bike. I would say do not worry about the difference, test ride bike before buying and buy only if the geometry fits you fine.

Check the geometry.  Some CX bikes are 'shorter' and more upright than some road bikes: my Boardman isn't and on 25c Vittoria Rubino Pro Tech it rolls very nicely.  Knobblies would obviously make a big difference.

If it's just the vibration on the hands you're trying to avoid... try simply putting bigger tyres on your current bike?

I've got a Wilier Cross-Carbon Di2 which I use as my Winter bike. It's got 28 mm Conti 4 Seasons and a 50/34 chainring and 12-32 cassette. Weight 8.7 kgs with pedals. I go up the same climbs as on my other road bikes (I live in the Pyrenees) but as it's about 1.5 kgs heavier I notice a difference - but I still get there!

Probably a few percent slower, more if your route is hilly, less if the road surfaces are poor. But this assumes a reasonably smooth road/gravel tyre: knobblies will slow you down a lot more.

I few years ago I tried swapping bikes around on the local club 10 mile TT: the audax bike was about 2.5% slower than the road bike and the MTB about 10% slower. A cross bike would be between the two: probably closer to the audax bike if you set it up with road tyres.

I have set most of my k.o.m's on my board man CX with either 32 or 28's on (slick) a lot whilst carrying a rucksack. True I tend to ride these roads on my commute and not on a Sunday but have always felt that the bigger tyres absorbed the vibrations etc from the crappy road surfaces allowing me to go faster for longer rather than bouncing around feeling fast but not going fast on skinny tyres. But I have set the bike up aggressively for speed so the aero ish effect helps too. 

Choice of tyre. Duranos heavy but bombproof 3 years thousands of miles not one puncture. 

GCN's Pimp My Commute episode

https://www.youtube.com/watch?v=8r4japmQbPY

They were looking at aerodynamics and put their tester on their standard road bike and full on baggy commuter clothes to an aero bike with lycra kit.

Standard road + commuter clothing: 58:32

Aero bike + lycra: 52:12

Psychology probably played a part there too.

Knobs will increase rolling resistance but tyre design and compound still matter especially as over time the tread will be wearing down.

E.g. 35mm Schwalbe G-One especially when run tubeless, would probably roll at least as fast as many popular commuting road tyres especially hosepipes like Gatorskins. The worse the road surface the bigger the advantage.

Personally my choice for fast comuting would be a pair of Schwalbe 30mm S-Ones run tubeless. On wider rims they would stretch to about 32mm and you wouldn't need to run them at more than 60-70PSI. Fast comfortable and with ultimate puncture protection.

As for body position, there's no reason why a cx / all road bike couldn't be set up  like a regular road bike.

Gearing might play a part. If its a 2x it may be that your quickest gear could be 46.11 - if its a 1x you could be as low as a 42x11 (or 10 for SRAM). If you are fairly powerful (18mph average commute sounds good) then you might find - on road tires at least - that you could overrun the gearing. On CX knobblies you probably wont though.

Maybe round 10% slower. 

What I did was look at my first road rides on my old Specialized Stumpjumper Evo HT 29er after a 4 year break (big knobbly Specialized Purgatory Control tyres). Average speed was 14mph.

Then looked at my first rides on my carbon fibre road bike this year with Continental 25mm tyres (after a 5 year break from cycling). Average speed was 17.5mph.

That's a 20% difference. 

Probably around 2kg weight difference between the two bikes (the mountain bike is actually pretty light which is why I listed the model, probably comparable to cyclocross bikes) so the main difference here are the tyres. 

Cyclocross tyres are somewhere in between road and mountain bike so I just halved the 20%.

Rough calc puts you at 16.2mph.

A lot of these cyclocross bikes actually have more roadie looking fast tyres, so you could be looking at 17mph. The weight difference won't be that noticeable. Less than .5mph.

Hi.  I have an Enigma Ecroix, which is basically a gravel/cross bike with massive tyre clearances.  What I've learned is that if you have knobbly tires at about 35c they tend to be noticably slower, and you can actually hear the drag noise when on the road - but I have normal 28c road tyres on mine most of the time and don't really notice any difference, even with a huge headtube which keeps me as far away from a racing position as possible!  I have even been paying attention to the weight of late, and have managed to get the bike down to about 8.7kg. 

CaadX seems like a lovely bike.