When Jim Thijs registered to return to the Traka, he knew he needed help. Something more. Having raced it prior on a more traditional gravel bike, and having not particularly enjoyed that experience, he knew he needed something more comfortable but, since this is the Traka we’re talking about, also fast.
The result? A drop-bar Specialized S-Works Epic World Cup with DIY aero fairings. This isn’t the first attempt at aero mods on drop bar bikes, but Thijs’s monster gravel bike looks far more refined than past efforts, even those from the pros.
“As much as I am convinced of the importance of aero in gravel, the speed and comfort of a full suspension bike on this particular course outweighs all other aspects,” Thijs explained after racing Traka on his wildly modified aero Epic World Cup.
When it comes to the Traka, Thijs know’s what he’s talking about.
“I live on the Traka course and every ride I do is basically on the Traka course. So I have a good understanding of what works and what doesn’t,” Thijs explained. “Many parts of this course are very similar to marathon mountain bike courses. A full suspension mountain bike is without a doubt the most efficient bike to ride off road, it just lacks aerodynamic features. So once I was sure I wanted to be on a fully I just tried to make my aerodynamic penalty as small as possible.”
Making the Epic aero
The first step was to change up the cockpit. Flat bars were swapped out for a Roval Rapide 38×75 one-piece carbon fibre bar/stem combo. With a 100mm Fox 32SC fork, Thijs said he could get in the same position as his road bike, adding “That is, of course, the biggest aerodynamic gain over a standard mtb position.”
But Thijs didn’t stop there. When you’re racing for over 10 hours, little details can compound into a big improvement.
“I wanted to get rid of the round tubes on the bike. On the frame, there is nothing we can do. But, by adding fairings to the fork lets and seat post, we could gain around three watts.”
Thijs came up with the concept and design of the fairings. His friend Hugh Rowlands (who happens to be an MEng in Aerospace Engineering), worked those ideas though through CFD simulations, design and 3D printing. Neither is planning to sell the design, since Thijs says it’s quite specific to his seat post, fork and their design to hide the front brake hose from the wind.
After racing Traka 360, Thijs said the bike elicited quite the reaction, making it a totally different race experience.
“It was crazy! During the race other participants and spectators were regularly shouting towards me that they saw my bike on Instagram. After the race people were in line to take pictures of my bike.”
Should everyone do this?
Thijs is, despite going to great lengths to optimise his own bike for Traka, quite pragmatic when asked if other riders outside the pro ranks should consider doing the same.
“If you are doing gravel events for fun and the only goal is to complete the distance you don’t have to think about aerodynamics. But the moment you start thinking about ways to cover the distance as fast a possible you should absolutely consider optimising everything to go fast and improving your cda is the easiest way to go faster.”
As he points out, it’s not like amateur riders shy away from spending money on personalising their rigs. Cycling culture usually tells us to chase different priorities.
“It would be ridiculous to spend a few thousand dollars extra on a bike to make it 200 grams lighter which has zero impact on your overall performance,” Thijs explains. “It is better to spend those resources to optimise your aerodynamics. Even if we had quite some elevation during the Traka and we started with many participants, I was surprised how many hours I spent on my own riding around 30k/h. In those moments a few aero gains have a big impact.”
Full spec: Jim Thijs aero Epic World Cup
Bike: Specialized S-Works Epic World Cup (Size L), SRAM Red XPLR, full CeramicSpeed bearings, Roval Rapide cockpit 38×75, 170mm SRAM XX1 cranks with Power2Max spider and 38T Garbaruk chainring, Fox 32SC Factory 100mm fork.
Result Traka 360: 13h10m finish time, 107th overall, 10th age group (M45-49)