Attacking “the Hour” on a T4

On Jan. 22, Bridie O’Donnell will try to break the UCI “Hour Record” of 46.273 km (the greatest distance any woman has cycled in 60 minutes from a stationary start). We know the Aussie rider is training intensely for her big day on the boards at the Adelaide Super-Drome — in part by competing in the Cycling Australia Road National Championships this week — but how is her track equipment shaping up? Like current record holder Molly Shaffer Van Houweling, O’Donnell is riding a Cervelo T4. 

Sport Scientist Ken Ballhause, answers a few of our bike-related questions: 

Cervelo T4 Adaptive HP.jpg

Q: Why a Cervelo T4?

A: It’s a logical choice when considering frame options for an event like the Hour Record. For a track bike, the relatively low bottom-bracket height makes the T4 a more stable option than other track frames. The T4 has optimal stack and reach measurements, making revisions to front-end setup pretty easy in the grand scheme of things. In part, it is this well-refined geometry package that makes it our frame of choice. 

It also helps that the T4 is the most aerodynamic of the accessible track frames on the market. Most Hour Record attempts are made on bespoke frames converted from TT to track applications, whereas this attempt will be made using technology accessible to anybody with a desire to purchase it.  


Q: Why did the team choose to move up to a size 54 frame?

A: The reach of the frame (effective length), combined with the stem/base bar geometry, provides us with an optimal position for pad reach (length to the elbow pads). The stack measurement of the 54 also allows us to use a sensible number of elbow pad spacers to achieve our desired pad stack (height of elbow pads). 


Q: How have you optimised Bridie’s body position?

A: In a sense, we have bypassed the typical kinematic methods (analysis of joint angles) for defining bike fit. We are confident Bridie’s time-trial experience and previous bike-fit sessions have allowed her to arrive at a saddle position (height/saddle offset) and pad-drop position that work for her morphology. These are the main components that contribute to hip, knee and ankle joint angles, and are the components of “bike fit” that we have kept consistent. The time she has been racing and training in her existing position means she is well-conditioned to operate at these joint angles, and we know they are sustainable under race conditions.

The key variable here is Bridie’s TT experience, as a very different approach is required when trying to transition someone with minimal TT experience into an effective TT position.   

Since aerodynamic drag has such a huge impact on performance, our approach to position optimisation has revolved around refinements to hand, forearm and elbow positions. These small changes to arm positioning have allowed greater comfort without a cost to Bridie’s coefficient of drag (CdA). The goal here has been to optimise the consistency of her position to allow an improvement in her ability to maintain the position for the full 60 minutes. 


Q: How were the aero testing sessions performed?

A: They revolved around in-the-field aero testing using the Alphamantis Technologies system. Initial testing confirmed Bridie’s low starting point for CdA, and from an aerodynamics perspective confirmed a good baseline position. It also gave us a target when it came to the refinement of the front-end setup. Her position is wider in elbow stance, longer in pad reach and longer in her contact point with the end of the extension bar; this has effects further up the chain. Consequently, we have arrived at a position that is more comfortable and more sustainable, while actually reducing her CdA value from baseline testing.


Q: How is Bridie’s progress towards her attempt?

A: We are starting to see a lot more consistency in her track work. Be it the longer efforts working at, or very close to her threshold, or the shorter efforts in a fatigued state. We are seeing less fluctuation in cadence, power and lap time – she is holding a tighter schedule that is for sure.
The Hour Record is not only about having the physiology, but the conditioning around performing at the limit of what is possible, and doing so in adverse conditions (heat). Consistency of effort is a major factor in managing the physiological toll. There is a lot of work that has gone into these improvements in consistency, including position optimisation.
Come Jan. 22 I am expecting we will see a very well run attempt on Bridie’s behalf.