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Here's why Surface Pro is less portable than an Ultrabook

Surface Pro might seem like the ultimate portable PC, but is it? And might you be better off with any other touch-capable Ultrabook?

A lot of people I've spoken to about their intention to buy a Surface Pro have cited that they want something "more portable" than an Ultrabook.

What I've been saying to them is that I believe the Surface Pro will be much less portable than an Ultrabook. They asked me to prove it. I'm going to prove it to you too.


When I was about, oh, 22, I nagged my boss into buying me a laptop to use at home. The win for him was that I could do work at work and also work at home. The win to me was that I would have a computer at home when the one I had was no good. The program of nagging I instigated would have made any five-year-old child proud, but after what seemed like months but was probably days my boss sprung for a Panasonic laptop. The specs I can't remember, but I do remember that adjusting for inflation this thing cost about 20% of my annual salary. It was also a classic notebook form-factor clamshell laptop.

In the intervening years I've owned (guessing now) 8 laptops -- none of which have cost 20% of my salary, but all of them have been notebook form-factory clamshell laptops. The one I'm writing this on -- my MacBook is such a thing.

The design of the clamshell is well-known -- as a designer of such things you put all the hardware in a base, lay a keyboard on the top, and attach a lightweight lid that contains a screen. The bulk of the weight of the device is in the lower portion. Even Ultrabooks, Intel's perceived saviour of the PC industry, follow this design. Look at the Ultrabooks coming out of CES this month -- they'll all clamshells at heart. (Well, one isn't, so we'll assume that's the exception that proves the rule.) Apart from a flirtation with tablet editions of Windows in the early 2000s, to all intents and purposes every laptop ever sold has been a clamshell.

Now look at the Surface Pro. It's the only, um, what? Tablet? Laptop? Thingummy? Well, it's the only PC tablet-slash-laptop-slash-thing that isn't a clamshell device. The key decision for potential Surface Pro customers to make is whether you they want to buy something that to all intents and purposes is an Ultrabook, but yet runs against three decades of wisdom as to how you build a portable PC.

There are two problems with the design of Surface RT and Surface Pro when you want to use it when mobile and in "laptop mode": the footprint, and center of gravity.

Incidentially, I'm ignoring weight. That might be convenient, but in Laptop Land, even relatively large variations of weight -- even up to a couple of pounds -- don't have that much effect on how portable a unit is. Yes, it's nice to have it light, but if it's in the bag, on your desk, or on your lap, you have quite a broad range of "good enough" values for the weight. You will also note that I'm ignoring the fact that Surface Pro can be used as a tablet. Windows 8 is not a good tablet operating system and my position is that anyone buying one will use it as a laptop first and foremost, and a tablet on very rare occasions.


To measure the footprint I've used my Surface RT as I don't have access to a Surface Pro. (And I've assumed that for our purposes any variations in size are not relevant.) It might surprise you that the depth of footprint for a deployed Surface is -- more or less the millimetre -- the same as a 15" non-retina MacBook Pro. The depth is 9.75" (250mm).

Frustratingly, I also don't have access to an Ultrabook, but I do have an 11.6" Acer C7 Chromebook here, so I'll use that for comparison. The footprint depth of that is around 20 percent less -- 8" (200mm).

Here's an illustration:

Surface and Chromebook Footprints compared
These photos show the relative depth of footprint of a Surface RT and 11.6" screen Chromebook compared. Note how the Surface has the same working footprint depth as a 15" non-retina MacBook Pro, despite it's tiny size.

The reason why I wanted to point this out is that I don't think this is coming across in the market perception of this product at all. The Surface is is -- when deployed -- has a footprint substantially larger than an Ultrabook with equivalent screen size.

Center of gravity

The more serious problem with Surface is its center of gravity.

On Surface, the center of gravity is located (let's assume) in the tablet unit, at about 3.25" (80mm) above the surface it's resting on. On my non-retina MacBook Pro, the center of gravity is 0.25" (6mm) above the surface it's resting on. On an Ultrabook , this value will be even smaller as Ultrabooks are typically much thinner than my old Mac.

Also, consider that with a clamshell laptop the center of gravity is (simplifying) in the middle of the actual unit, so all the weight acts downwards evenly. In Surface, the center of gravity is not only quite a long way up in the air, it's some way back from the far edge of the Type Cover keyboard. All of the mass of Surface is acting where there is very little friction -- which I'll get to.

I have created these photos that shows where the centers of gravity appear to be the Surface RT an Chromebook. I should say I did this by balancing the device and feeling where it was, rather than using actual math -- I'm afraid that my math is too weak for that task!

Surface and Chromebook Centres of Gravity
*Very* approximate centers of gravity of the Surface RT and Chromebook compared. Assume the Surface RT is a Surface Pro, and that the Chromebook is any normal clamshell laptop, Ultrabook or otherwise.

Next, with a clamshell you have the potential of the entire footprint of the device being in contact with the surface that it's resting on. Most laptops have little feet for use on desks, meaning the actual contact area on a solid surface like a desk will be measured in millimetres, but on an uneven, soft surface like a lap there is much more contact, lots of downward force (i.e weight), and lots of friction.

With Surface the maximum possible contact area with your lap is almost entirely defined by the area of the Type Cover. The problem here is that the Type Cover has relatively little mass (0.5lb, or 226g) to hold in place a much heavier mass (2lb, or 907g). There is very little downward force acting where the actual contact with the supporting surface is, hence not very much friction. In fact, any friction that there is would be virtually nothing compared with any clamshell laptop.

On a desktop this isn't so much of a problem because there are typically no external forces shifting the desk around under the laptop. Earthquakes aside, no forces are going to militate against that the device's decision to stay where you've put it.

On a lap though -- good luck. You can find people like me who will tell you that Surface RT just about works on your lap, but they're likely to tell you that it's not a pleasant or particularly workable experience.

The first problem you have is that the whole device footprint -- and remember, it's the depth of a 15" MacBook Pro, which is big -- has to fit entirely between the top of your thighs and your knees. Now, admittedly I'm not that tall, but I can only just do that. And when I do, the keyboard is so close to my torso that it's hard to type. With a normal clamshell, the total length of your thigh doesn't matter so much. The back of a clamshell laptop can protrude past your knees and not be unstable because there's enough friction created by the part that is in contact with your lap.

(Importantly, I know people who's legs just aren't long enough to be able to accommodate the Surface deployed in this way. If you are on the short side and you're convinced Surface Pro is the device for you, an audition would be in order.)

OK, so imagine you're on a train and you have the Surface Pro balanced on your lap and it stops suddenly. The chances of the Surface Pro sliding off your leg and skittering across the floor of the carriage is much higher than a normal clamshell laptop because a) the friction created by the Type Cover is much lower and b) most of the mass is located ahead of the Type Cover and that will have the effect of pulling the device forward. (Physicists please note: I've oversimplified that point.)

All of this is about stability. A clamshell design is very stable. Surface's design is, in contrast, very rickety. Stability you can ignore -- ricketiness you have to proactively manage.

But wait, there's more…


Let's say it's your job to layout the cabin for the new Eurostar. (I use this as an example as I recently went on the Eurostar to Brussels and noticed the problem I'm about to describe.) You know that business people use the service, and you know that business people use laptops. If you're a very modern thinker, you may assume that business people also use iPads.

Say you want to layout four seats, two pairs facing each other with a pair in the middle. Your mental image of what a laptop looks like is not weirdness that is Surface -- it'll be a traditional clamshell design. And so you get four people and four laptops and you arrange the people in the seats and the laptops on the table and you tweak and adjust until you get some balance of comfort and utility mated with the commercial considerations laid down by the train operator.

The point is that that table size will have a compromise biased towards clamshell laptops and entirely unaware of Microsoft's design imperatives re the Surface. The table almost certainly won't have enough space to comfortably put two laptops back to back directly on the table surface. On my trip to Brussels the gentleman sitting opposite me wanted to use his ThinkPad. It was -- I think -- a 13" model. In order to share the space like normal human beings we both had to have the front edge of our laptops protruding off of the front of the table by a couple of inches. With a Surface you can't do that. If you push down on the front edge of an unsupported Type Cover -- either accidentally, or by typing -- the whole thing levers back and collapses because the center of gravity is way up in the air and way back from the far edge of the Type Cover. You can just about make this work if you hover your arms above the whole unit and tap gently on the keys, but it's not a pleasant experience.

Of course, some of you may not go on trains that often. Planes, to be honest, you might have more luck with. Airline trays are around 10" (254mm) in depth, which as we've seen is about the same as the footprint depth of Surface. If the person in front rakes their seat back, you'll likely have to pull the front forward, and then you're back into the levering problem as per the train example. Plus, the point still stands -- people who layout plane cabins are grudgingly accepting you might bring a clamshell laptop along for the ride. They're not figuring on you bringing along and setting up some weird, unstable contraption.

So at this point we have:

- Surface on a desk. Fine (but the screen is too small).

- Surface on a lap. If you're under 5'7", you will likely not be able to fit it on your lap. And if you are 5'7" or over, it really is a case of proactively balancing with a much higher risk of it falling to the ground than a laptop.

- Surface on a plane or train table. Your mileage may vary, but it's likely to be much less usable than an Ultrabook with a similarly-sized screen.


I'm all for innovation, but bear in mind that Microsoft's intention with Surface's design was to target the iPad, not to progress the decades old story of how laptops are designed. Both Surface RT and Surface Pro are intentionally designed so that if you put an iPad with a keyboard side-by-side with them you're supposed to think, "Hey! I can haz a keyboard with an iPad?"

Laptop designers, for better or worse, have ignored Microsoft's lead with Surface and built a new tranche of laptops that are the same as they did before, but they happen to have touch. That in some sense is a logical evolution. It certainly doesn't break a many-decades-long understanding of how we build laptops.

As a society we have certain expectations from a laptop that seems to be best served by a traditional clamshell design. If you actually need a keyboard on your device, hiding the device electronics beneath that keyboard and having a lightweight lid containing a screen seems to be the design that's most sympathetic to how people want to do mobile computing.

The question is then -- do you still think Surface Pro is more portable than a normal clamshell Ultrabook?

What do you think? Post a comment, or talk to me on Twitter: @mbrit.


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