RCUK cyclo-cross bike build 2013: part one – frameset

Specialized CruX Pro Carbon chassis with disc mounts

Winter is grinding its way into view, and thoughts at RCUK Towers have turned to a custom build for the season.

Following last year’s highly successful Kinesis Racelight TK3 project (a machine that has become our de facto test rig for wheel and component tests) will be a tough task, so this year we’ve decided to attempt not one, but two winter bike builds.

First out of the traps is our cyclo-cross project, and we’ll come clean immediately: we’re staring down the barrel of a far more exotic build than we’d planned. Never ones to look a gift horse in the mouth, however, when Specialized UK offered us a CruX Pro Carbon frame with disc mounts as the chassis for our endeavour, we nodded vigorously.

The chassis at the centre of the RCUK ‘cross bike build: the Specialized CruX Carbon Pro

So what do we have? Well, Specialized appear to have employed a number of design features from their successful road range, and as such we have an oversized carbon frameset that includes features such as a tapered head tube, supplied with integrated cartridge bearings. The headtube tapers from a 1-3/8” lower bearing, in common with those of the Tarmac and Venge. The bottom bracket is another oversized affair, and again loaded with integrated cartridge bearings. The design team at Specialized has included spacers to fit a Shimano Hollowtech II-style chainset, removing the need to source third party adapters.

The top tube is flattened on its underside to make it all the more portable up the ‘staircases’ and over the hurdles that litter the ‘cross courses on which a machine of this calibre is deployed (see Ian Field’s impressive performance in Tabor last Saturday). Also worthy of note is a subtle, mudguard-style shaping to the underside of the down tube that should provide some level of protection from front wheel spray – another considered detail. The frame runs a braze-on style front mech mount and is also fitted with two sets of bottle bosses, the latter likely to be some use if you plan to go longer than just an hour in hell.

The CruX Pro Carbon frame comes in disc or cantilever configuration, but with the former occupying many column inches on RCUK and elsewhere, the opportunity to include them in our build was too good to pass up. These are post mount, front and rear. All cables/hoses/wires are routed internally for a nice clean look, but more importantly perhaps to help prevent snagging. Both frame and fork sport aluminium dropouts: an excellent choice in our opinion, due to the longevity they should offer over carbon: cyclo-cross bikes can be subject to a lot of wheel changes.

The Specialized CruX Carbon Pro’s oversized bottom bracket comes fitted with an integrated and sealed bearing

Up front, we find a full carbon fork with a steerer to match the aforesaid tapered headtube, which, along with seat and chainstays, appears to offer good mud clearance. It’s supplied with an uncut steerer, placing fit in the hands of the owner,  and with carbon headset spacers.

The CruX Pro Carbon frameset also ships with an offset carbon seat post: Specialized’s own Pave Pro SL, a single bolt unit in a 27.2mm diameter, the last an increasingly popular trend with manufacturers looking to induce compliance. Towards the bolt, there’s a damping insert, too: a nice detail.

The frame, fork, headset, bottom bracket, seat post and collar tipped the RCUK scales of truth at 2090 grams. The Crux Pro Carbon is a frameset that has clearly had a lot of thought put into it. We think that the blue and lime paint scheme looks fantastic, and we’re looking forward to seeing just how the bike comes together in the coming weeks.

Check back soon to see the progress of the build.

If you want to find out more about cyclo-cross bikes, take a look at our cyclo-cross bike guide.

Discuss in the forum

Price: £1500
Size: 49cm, 52cm, 54cm, 56cm, 58cm, 61cm
Colour: Satin Carbon/Charcoal/Multi Keyline or Blue/Black/Lime
Website: Specialized UK

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