Cyclo-cross bikes

Cyclo-cross bikes

The first cyclo-cross bikes used were anything that the riders could cobble together for use off road, but as the sport developed the bikes soon became more specialised. This article describes the development of 'cross bike.

Cyclo-cross is a hybrid of cycling and cross-country running. It's a post-war phenomenon which reached in the UK in the early 1950s, largely practised by racing cyclists as a winter activity to keep some of their racing fitness rather than ride traditional long club runs. It is now a UCI recognised cycling discipline with its own World Championships for Elite riders, Under-23, Juniors, Women and Masters. As cyclo-cross races began to get more serious and recognised as a legitimate part of cycle sport, so the bikes began to develop into a more specialised design.

'Cross bikes soon appeared with:

  • Higher bottom bracket heights - to allow riders to pedal over uneven ground without catching their pedals.
  • Brazed-on cantilever brakes - to reduce likelihood of collecting mud (in preference to sidepull or centrepull brakes which wrapped around the tyre).
  • Specialist tubular tyres with aggressive, knobbly treads.
  • 'Handlebar control' gear levers, which plugged into the ends of the handlebars, enabling riders to change gear and keep control of their bikes at all times. For years these were the true sign of a 'cross bike.
  • Single-chainrings (with a guard to prevent the chain from jumping off) - usually between 44 and 48 teeth.
  • Wide ratio freewheels (ranging from 13 or 14 to 26 or 28 teeth) were the norm, but in the 1970s Continental riders introduced double chainsets and the front gear mechanism obviated the need for the chainguard.
In the 1970s the lightweight Italian-made 'Alan' bonded aluminium frame became popular - it appealed to the cyclo-cross riders who needed to shoulder their bikes frequently to tackle run-ups and obstacles during races. A dedicated cyclo-cross version was produced and all the top riders started using them - guaranteeing their popularity amongst amateur riders too, right up to today. 

In the 1970s the lightweight Italian-made 'Alan' bonded aluminium frame became popular

During the 1990s racing evolved from the 'mud-plugging' of the early races, to more rideable courses which were drier, with less carrying and running, making the racing faster and more exciting. This, along with the advent of the mountain bike changed the design of the frames again.

The Alan frames restricted tyre sizes due to the limited width of the fork crown and chainstays. However, following the advent of new materials and joining methods coming in from mountain biking, frame designers increased these clearances to allow bigger tyres (35mm section or more) on 700c wheels without the frame clogging with mud. (Bigger tyres can be run at a lower pressure to provide more traction on soft, off road surfaces).

Today, a typical modern cyclo-cross bike has:
  • Frame made from welded, 'oversize' aluminium.
  • A high bottom bracket to give adequate clearance over rough ground.
  • Cantilever brakes (still the brakes of preference.
  • Disc brakes are beginning to emerge on the 'cross circuit. Again, this is a cross-over from mountain biking.
  • All the brake and gear cables running along the top of the top tube (keeping them out of the mud and away from the rider's shoulder for those moments when running and carrying the bike is still required).
  • There are no fittings for bottles or race numbers.
  • Frames are 'clean' for swift and easy shouldering.
At top level most riders still choose sprint rims with tubular tyres of 28-35mm section. The box-section of sprint rims makes them inherently stronger than high-pressure rims (sometimes also called 'clincher' rims) which have an open U-section, and so sprints can better withstand the sort of knocks they get in this type of race, plus they are lighter than conventional 'clincher' rims. However there are some excellent conventional tyres, mainly Michelin, designed for specifically 'cross and these are much easier to repair.

Double-sided mountain bike 'SPD' pedals are the norm

Double-sided mountain bike 'SPD' pedals are the norm, partly because they usually work well in muddy conditions and provide a secure interface between shoe and pedal but also because they avoid any faffing about with toe-clips and straps or searching for the clip mechanism on single-sided pedals.

STI (Shimano) or Ergopower (Campagnolo) integrated gear and brake levers are typically used for 'cross. The formerly ubiquitous 'handlebar control' has become almost extinct.

Double chainsets are preferred, 39-50 teeth being a common combination - with perhaps a cassette of 12-26 teeth although some of the faster courses warrant gears closer to the roadman's 52 or 53 tooth chainring and maybe only a 12-21 cassette. In cyclo-cross, if a hill is too steep to ride comfortably the rider just picks up the bike and runs with it!

Top riders race with at least two bikes, so if one gets muddy they can change bikes each lap

Top riders usually race with at least two bikes, so if one gets muddy (which makes it both heavy and reduces its efficiency) they can change bikes each lap, with a helper cleaning the muddy bike in readiness for the next lap changeover.

Cyclo-cross is getting very big in America so expect more changes soon as they apply their philosophy of 'Don't say why? - say why not!' to this branch of the sport. Look what happened when they discovered the Tour de France!

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