2015. The Year Of DISC-overy.

Words by Mark

on 02/12/2014 13:40:00

Giant Defy Disc

You could be forgiven for thinking that road cycling is slow to adopt technological advancements. A cursory glance at a road bike frame from five years ago against a 2014 model presents very little in the way of change. The diamond frame remains largely the same with the exception of fashionable paint jobs.

The evolution of road cycling largely seems to have stalled. Many of road cycling's technological leaps have not been leaps but subtle refinements to an already sound logic. Geometries specific to different styles of riding have been around for a while and the semi-aero concept was cutting its way a long time before Specialized's Venge ( Felt's AR). This year sees Trek's Emonda acquire lightest production bike status, it's a hell of a bike, but the weight card has been played its final time. There can surely be no further enhancements down that road, without producing a bike that rides like two unicycles strapped together.

Di2? Six years old.


2015 sees bike manufacturers begin production on their road disc brake models. Whilst the transfer from MTB to Road may have been, for many, a little hard to swallow, the growth of cyclocross as a discipline developed a necessity for a brake that performed better than a rim brake. Cyclocross is arguably the muddiest form of cycling there is, and it makes little sense to use a brake that MTB kicked out years ago. The disc brake was adapted and evolved to allow a reservoir to be concealed in a road shift lever.

After a few false starts hydraulic discs have now become road functional and they are bloody good! Stopping power is so hot that even the pros aren't allowed to use them (yet!) in case it destroys an entire peloton. They are destined to be road's next super weapon.

It's not as simple as just drilling some holes on forks and stays, and then slinging a calliper through - frames have to be designed from the ground upwards. Take Giant's Defy as an example - the 2014 and 2015 are very different beasts.


The 2014 is pretty much how we've come to look at an endurance road bike, relaxed geometry with a lowered seat stay - to allow the vibration from the rear wheel to be dampened. Compared to the 2015 model it now looks outdated.


2015. The front end is designed to resist the forces generated by the braking power - the head tube is less of a tube and more a complete melding of the head tube and down tube. A stiffer front end is not great for endurance riding, but an increase rake on the fork takes care of that. In comparison to the 2014, the back end is lean - the seat stays are flatter allowing more vertical compliance, whilst still resisting lateral forces. The chain stay is deeper too, once again, resisting force applied to the frame from braking. Whilst last year's Defy has a chunky aero looking seat post, it wasn't the best for removing surface noise from the tarmac. The new D-Fuse design draws its strength from the beefed up top tube/seat tube intersection, and utilises thinner tubular design to provide up to 12mm of fore and aft flex. This gives plenty of soak up of vibration and gives a ride that is eerily smooth.

But does the 2015 Defy still perform? Well, that down tube will make sure all effort goes to the wheels - due to the increase in width and the flattening to the BB shell that both prevent flexion.

Overall Summary

Discs are here to stay, and whilst that represents a logical step rather than a leap, their presence has meant a re-think on how shift components and frames are designed.

The next stage in road cycling has arrived!