Paris-Roubaix is unique. No other race brings out the special equipment like the Hell of the North. The cobbles are famous for their savagery and for this reason, the teams pull out all the stops.

The one most notable change is the increase in tyre size, up from the 25mm's favoured at Tour of Flanders to 27mm and, in some cases, even 30mm tyres. FMB's Paris-Roubaix 27mm tyres was the outstanding favourite on display this weekend.

The other big change to the bike happens on the chainset. Most riders opting for a 44 or 45 tooth chainring in place of the regular 39 chainring. There isn't any climbing on the course to speak of, but some of the cobbled sectors have enough gradient that pushing a big ring takes its toll - but sucessfully negotiating the pave requires you to hit it at pace and keep in the biggest ring you can - if you have to chance down you don't want to change down far because if you're rivals put any distance in to you on the later section you won't be getting it back.

Cannondale Synapse HM

Most of the Cannondale team have been riding the new Synapse replacement that we spotted at Flanders last week. We don't actually know it's a Synapse replacement, there's been no official word from the company yet. We're led to conclude this because the bike has clearly been designed in the endurance mould, with very skinny shaped stays, a new fork and that split seat tube, which all lead us to conclude they're there to provide shock absorption.

Further evidence this is the new Synapse comes via the UCI sticker, which here has been cannily covered up by the frame size sticker. All bikes have to be approved by the UCI before they can be raced. A look at the UCI's list shows the inclusion of a Synapse HM (high modulus), dated 14.01.2013.

The very interesting seat tube junction. The seat clamp is integrated into the frame, similiar to the Slice RS time trial frame, presumably for aerodynamic reasons. We're guessing there's an expanding wedge inside, and notice also the small bulge between the seat tube and top tube, This houses the seat clamp unit. That's a 27.2m seat post.

Cannondale have opted for internal routing for the gear cables, passing them through the downtube. The Evo only has the rear brake cable routed internally, which the Synapse mimics. An oversized head tube houses a tapered 1-1/8” to 1-1/4” steerer tube from the brand new fork.

The all-new fork is very different to the one used on the SuperSix Evo. It's more curved and has some similarity with the Trek Domane fork.

The rear gear cable pops out the end of the chainstay. Carbon dropouts with an aluminium mech hanger. SRAM provide custom coloured components for Cannondale, very neat.

From this angle you can see just how shapely both the seat and chainstays are. Cannondale have good experience with shaping carbon to control flex. They once produced a full suspension bike that relied on controlled flex in the chainstays in preference to a heavier pivot. The challenge is to offer a degree of vertical flex to smooth out rough roads while still having stiffness for power transfer, sprinting and climbing.

A closer look at those chainstays.

The most interesting design feature is the split seat tube at the junction where it meets the bottom bracket. How much this novel design contributes to ride comfort is unknown at present.

Bianchi Infinito CV debuts at Paris-Roubaix

We covered the new Bianchi Infinito CV at the launch last week, Mat and Tony even got to ride it ahead of the race.

This is Juan Antonia Flecha's bike (can't decide if that blue bar tape really works with celeste - obviously it works for Juan though).

The deal here is the Counter Vail carbon layer that forms an integral part of the frame and which is constructed in such a way as to damp high frequency shocks - the idea is that it adds stability - check out our pics of Mat riding no hands on the Carrefour cobbles - and reduces fatigue.

Flecha rode this bike to 8th place, afterwards he said it was the best classics bike he'd ridden in his career.

Matti Breschel's Specialized Roubaix SL4

Here's Team Saxo-Tinkoff's Matti Breschel's Specialized Roubaix SL4. All Specialized sponsored riders had switched from the Tarmac used last weekend at Flanders to the Roubaix, a bike named after this race and designed with shaped seat stays and Zertz inserts to smooth the ride.

The unique Zertz inserts. Specialized were one of the first company's to incorporate such a design in the pursuit of ride comfort, and it's paid off, it's one of the most successful bikes at the classics in the past five years.

Saxo are sponsored by Prologo and most of the team had the new Scratch CPC saddles. You usually see saddles covered with sticky tape or adhesive patches in time trials, to prevent sliding when perched on the nose. Less of a problem on the pave, but the extra grip offered by the unique saddle could make a small difference.

Team Sky's Pinarello Dogma K

Team Sky's great hope was Geraint Thomas, and for this race there's very few changes from last weekend, other than the tyre swap, for his Pinarello Dogma K.

The team mechanic told us the reason for not using the new 11-speed Di2 is because they only received it in January, and didn't feel they had enough time to get it setup and the riders comfortable with using it. So they're sticking to tried-and-tested equipment.

Most of the team are still running non stickered Shimano C50 tubular wheels.

Though the branded C35 was common too. Tyre choice is the same across the team, FMB Paris-Roubaix 27mm tubs.

An unusual saddle choice. Most run the same saddle regardless of the cobbles, but Thomas has chosen the more deeply padded Fizik Tri 2 saddle. It's a triathlon saddle. Those two marks are to set up the saddle to bar reach.

Riding in the hoods and changing gear is very challenging on the pave, and a favoured riding position is to clasp the tops of the bars. The really neat trick with Di2 is the remote shifter box that can be zip tied to the centre of the bar, positioned to the right of the stem. This will be a huge benefit on the longer cobbled sectors.

Edvald Boasson Hagen even added the optional sprinter shift levels to the inside of the bars, giving him

Yes that's a long stem, 13cm to be precise. It's a PRO PLT stem, an aluminium construction that isn’t even the top-end model, with a custom Team Sky paint finish. A set of aluminium PRO handlebars completes the build kit.

A neat little rubber bumper to stop the cable rubbing and rattling against the frame.

Doiuble wrap bar tape for Thomas.

Thomas is proud of his Welsh routes. Any of his Twitter followers will know he has a fondness for welsh cakes. A smart little detail on his bike is this four-leaf clover, a symbol that was used by the early Celts of Wales to ward off evil spirits. Didn’t work for poor old Thomas though.

The frame and fork is the same Dogma K they've been using in all the classics. The most significantly visible difference to the 65.1 Think 2 is around the back, the seat and chainstays are vastly different. There's no wishbone, with the seat stays, very slender and curved throughout their length, join at the seat tube.

The carbon layup is also different too, and the fork is specific to the frame.

Most riders had ditched the 39t inner chainring, not much use on a course with just 250 metres of climbing, and fitted a 44 or 45t chainring. Edvald Boasson Hagen opted for a 44.

Edvald Boasson Hagen chooses a Fizik Versus Antares saddle with a recessed channel running the length of the saddle.

Europcar's Colnago Prestige cyclo-cross bikes

Years ago you would see an unusual sight at this race, cyclo-cross bikes aplenty. It's less common today, but Europcar fielded a full lineup of Colnago Prestige 'cross bikes. Why? So they could fit the fat 27mm tyres through the frame with enough clearance to avoid dirt, grit and stones potentially causing flats.

The new Scott Addict

There's two Scott sponsored teams at this race, and many of the riders had the option of the new Addict. Since the development of the aero Foil, there have been questions about when they would bring the Addict back, after removing it from the range. Well here it is. Obvious shared design features with the Foil but less aero shaped tube profiles and skinnier seat and chainstays in comparison to the aero bike.

It doesn't appear that Scott are pitching it as an 'endurance' model in the same way the new Cannondale and Bianchi clearly are. There's no official details from Scott yet on what the deal is here as they haven't officially launched it yet - our guess is it'll be a lightweight all-rounder which is probably stating the bleeding obvious.

Compared to the Foil, there’s more subtle profiling of the main tubes. The downtube and seat tube both enlarge in diameter to meet the press fit bottom bracket shell.

Cables are routed internally, as most modern frames are these days. The head tube appears to have a constant diameter between the two bearing cups, and we would expect to find a tapered steerer tube inside.

Loads of clearance for the 27mm tyres. Whether production bikes will have the same level of clearance remains to be seen.

The chainstays are very tall at the bottom bracket and tapered to the carbon dropouts, while the seat stays are profiled with a tapered size throughout their journey from dropout to seat tube.

This UCI sticker is a dead giveaway.

The main tubes are much less profiled than the Foil, the downtube has a squared off shape and the top tube is rounder and very slender in the middle. Weight has clearly been placed at the top of the list of priorities, right alongside stiffness.

It doesn’t seem to carry any features that would suggest it’s going for ride comfort, but as we’ve seen with the new Bianchi, they could have incorporated a particular carbon fibre technology and layup to achieve compliance, in preference to inserts, like the Specialized Roubaix, or a mechanical solution like the Domane.

GreenEdge's Baden Cooke was riding the new Scott Addict as well. He, like many Di2 favouring riders, had the optional shifter box zip tied to the centre of the handlebars, to the right of the stem. Gives them another option to change gear, they spend a lot of time riding on the top section of the handlebars on the pave and reaching the shifters can be tricky when the cobbles are throwing you all over the place.

Jurgen Roelandt's Ridley Fenix

The entire Lotto-Belisol squad are riding Ridley's Fenix, including Roelandt. The newest bike in their range, it was introduced earlier this year, and joins the Noah Fast and Helium SL, the two bikes that are the regular choice for all other races.

It's about about careful shaping and carbon layup of the seat stays and chain stays to deliver vibration absorption over the cobbles.

He has a 13cm Deda Zero stem with no spacers between it and the headset top cap. There's a 5mm spacer fitted above the stem. To remind him of the cobbled sectors,

Jurgen, like a handful of other riders, has their distance printed on a sheet of paper taped to the top tube. In fact, each Lotto-Belisol Ridley had the sectors neatly taped to the top tube, evidence there was a management decision to place the reminders on all the bikes. Other teams appear to leave it entirely up to their riders.

A San Marco Regale saddle is his favoured saddle. Deda Superzero carbon seatpost

A 53/46 Campagnolo Record chainset provides a close ratio for tackling the cobbles. The riders will spend most of the time in the big ring but some of the sectors, especially when you factor in the strong wind, will push many riders into the little ring. And having the very close ratio makes it less of a leap than from 53 to 39.

The mechanics use helicoil to tidy up the electric wiring, fixing it to the brake cable.

Preventing dropped chains – chains bounce around an incredible amount on the cobbles, and hindered Boonen's race victory hopes famously in the Arenberg a few years ago – is a key concern for the team mechanics. We're seeing less of the homemade solutions and more off-the-shelf products, and this one, attaching to the bottle cage mounts, is a very smart setup. Extra weight though, but can only be a handful of grams more than a front mech mounted type.

Focus Mares CX

More cyclo-cross bikes in evidence. Most of the Ag2r team were using the Focus Mares CX bike rather than the Izalco, for the extra clearance in the frame for the 27 and indeed the 30mm tyres we spotted on the bikes.

Arnaud Labbe's Look 586

Cofidis had a selection of Look models. This is Arnaud Labbe's 586, with a regular stem setup and integrated seat mast. Mavic deep-section Cosmic wheels with unbranded tubular tyres. It wasn't clear from the file tread pattern who might be manufacturing them.

Canyon Ultimate CF SLX

Katusha had the new Canyon Ultimate CF SLX at the ready. This is a major update to the model for 2013, and you can read about all the changes in this article.

Those fork legs are a little more slender than before, by the way – they’re not so deep from front to back. The idea there is to increase comfort.

Rounded square top and downtubes give the Canyon a purposeful look. The previous version has round main tubes. Cables are now routed internally as well. The changes have led to a significant weight drop, they claim it's well under 800g.

BMC GranFondo

BMC all rolled out on the GranFondo. This is the company's well regarded endurance model. You can see how skinny the seat stays are to provide some ride comfort, but notice how substantial the chainstays are in comparison.

The bike is aimed at the sort of rider who likes a high front end at the top of their list of priorities, it has a very tall head tube. So most riders had to resort to some extreme stem options to get the bars low enough.

Fabian Cancellara's Trek Domane

As the star rider and team leader, Fabian Cancellara has three team bikes, and each team car had a spare bike on the outside for quick access.

They're all pretty much identical, even down to the custom paint finish, which includes a Spartacus helmet on the head tube. Cancellara is a big Domane fan - he won first time out on it last year at the Strade Bianche and it's his bike of choice even on less challenging road surfaces over the Madone.

Yesterday's victory will have cemented it even more firmly in his affections. And after riding it over the cobbles on the Roubaix Challenge the day before I can see why he likes it so much - it is a truly impressive piece of kit, (more on my ride, and a brief chat with Spartacus too coming soon).

Team Blanco Giant Defy Advanced

Just like Flanders, Team Blanco again opted for Giant's Defy Advance SL, in preference to the TCR or Propel. It was a choice that paid off with Sep Vanmarcke coming so close to taking the victory. The Defy Advance is Giant's take on the endurance performance road bike - like the Domane and the BMC Gran Fondo marketed as a bike for the classics - if you're a pro - or the sportive (check that taller headtube) if you're not. It certainly went some way to justifying that billing yesterday.

The rear brake cable and Shimano Di2 wire is neatly routed inside the top tube and enters on the underside.

There's lots more Paris Roubaix tech, riding and general chit chat to come, just as soon as I get off the Eurostar…