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Friday, 30 December 2016

Tech Talk: Cannondale CAAD 12 Disc

Cannondale CAAD 12 Disc

Cannondale has a history in aluminium bikes that spans more than three decades, and while many brands have either shelved aluminium or relegated it the bottom end of their ranges, the company continues to advance the material alongside its carbon portfolio. The CAAD (Cannondale Advanced Aluminium Design) range, which was launched in 1983, has now arrived at number 12, although slightly confusingly the CAAD12 supersedes the CAAD10.

Cannondale turned to some pretty sophisticated new computer software and a proprietary design technique called Tube Flow Modelling. ‘In the past all we had to work with was tube thickness and tube shape,’ says Cannondale design engineer Jonathan Shutler. ‘Now the engineer defines the parameters and then the computer runs through hundreds of virtual tests, working on different options until it finds the optimal solution. It accelerates the testing and engineering timeline and unlocks more of the material’s potential through designs that engineers alone would maybe have taken years to get to.

Internal route

‘We can hone every detail of the frame – how gradual the tube tapers are, the precise changes in wall thicknesses,’ says Shutler. ‘On the CAAD12 there are no dents or crimps to provide clearance for the front mech or tyres etc. Everything is modelled. There are no stress risers (points where stress is concentrated), there’s no excess material, and we can concentrate the strength and stiffness precisely where it’s needed.’ It sounds remarkably similar to how carbon lay-up schedules are developed using FEA and CFD analysis,and reveals how far aluminium construction has advanced. But this is only the beginning. Next comes a complex mix of tube swaging, hydroforming, welding and post-weld heat treatments to bring the CAAD12 Disc frame to life.

Bridgeless seatstay

The tubes look mostly round, but subtle shaping sets them apart. The down tube has a low central ridge on its underside, flaring to maximise its head tube junction, and swaps ovalised planes at the bottom bracket. The top tube tapers and flattens before the seat tube, and Cannondale’s SpeedSave chainstays and Thinline seatstays aim to combine drivetrain efficiency with rider comfort at the back. The gear cables and rear brake hose are routed internally through the down tube, and the front hose is retained in a channel inside the fork leg by a removable cover, all helping to maintain the clean lines.


Tappered seattube

The carbon fork is moulded as a single piece with direct bearing placement for the headset to shed more grams. The bottom bracket shell is widened to 73mm providing a sturdy perch for the flared Delta seat tube, The seat tube tapers all the way up its length until it arrives at the skinny 25.4mm seatpost. The outcome of all this, say Cannondale, is improvements in stiffness (claimed 13 per cent more at the BB and 10 per cent more at the head tube), reduced weight (236g lighter for frame, fork, headset and seatpost) and dramatically improved vertical compliance (50 per cent) compared to the CAAD10.


Highlight:

  • Advanced aluminium construction
  • Disc brake with QR
  • Skinny seatpost with SAVE seat and chainstay for better vertical compliance

Glossary:

Toptube: The tube connect headtube with seattube.

Downtube: The tube connect headtube with Bottom Bracket shell

Seattube: The tube connect the toptube and downtube, its also home for seatpost.

Seatstay: The tube connect seattube with rear end 

Seatpost: A bicycle seatpost is a tube that extends upwards from the bicycle frame to the saddle. The amount that it extends out of the frame can usually be adjusted, and there is usually a mark that indicates the minimum insertion.

Chainstay: Tube connect BB housing with rear end

Bottom Bracket: The bottom bracket on a bicycle connects the crankset (chainset) to the bicycle and allows the crankset to rotate freely. It contains a spindle that the crankset attaches to, and the bearings that allow the spindle and cranks to rotate. The chainrings and pedals attach to the cranks. The bottom bracket fits inside the bottom bracket shell, which connects the seat tube, down tube and chain stays as part of the bicycle frame.

Headset: The headset is the set of components on a bicycle that provides a rotatable interface between the bicycle fork and the head tube of the bicycle frame. A typical headset consists of two cups that are pressed into the top and bottom of the headtube. Inside the two cups are bearings which provide a low friction contact between the bearing cup and the steerer.


Source: 
Cyclist ME Nov 2016
http://www.bikeradar.com
http://road.cc


Ride On!



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