What does it take to win the toughest ultra gravel race in the world?
Rob Britton takes us inside his record-breaking victory at the 2025 Unbound XL, the brutal 350-mile self-supported gravel race across Kansas.
Rob breaks down the key decisions that helped him average over 20 mph for nearly 18 hours and smash the previous course record by more than two hours.
From aerodynamics and nutrition strategy to hydration systems, gravel race tactics, and bike setup optimization, this episode explores how small performance gains compound over ultra-distance racing.
We also dive into the development of Castelli’s first Unlimited Gravel Suit, featuring integrated hydration storage, aerodynamic cargo pockets, and real-world testing at the highest level of gravel racing.
Topics covered in this episode:
•\tWinning the 2025 Unbound XL
•\tGravel racing aerodynamics explained
•\tUltra-endurance nutrition and hydration strategy
•\tIntegrated hydration systems in cycling apparel
•\tAero gains over 18 hours of racing
•\tGravel bike setup for ultra racing
•\tRacing through the night against Lachlan Morton
•\tComfort vs speed in endurance cycling
•\tThe future of gravel race apparel and technology
If you’re into gravel racing, bikepacking, endurance sports, cycling tech, or performance optimization, this episode is packed with insights from one of the fastest ultra-gravel performances ever recorded.
🎧 Subscribe for more conversations on cycling performance, innovation, aerodynamics, and elite racing.
– IMPORTANT LINKS –
CHAPTERS
00:00 Intro
02:38 Quickfire Round
04:05 Chasing Lachlan Morton Through the Night
06:21 Racing History with Lachlan & The Final Catch
07:05 Tactics, Fatigue & Managing the Lead
07:50 Bike Setup, Aerobars & Carrying Nutrition
10:38 Why the Speed Suit Could Have Decided the Race
11:58 How Ultra Racing Has Changed in Recent Years
13:32 First Ride in Castelli's Prototype Gravel Aero Suit
15:25 Nutrition Storage, Hydration & Self-Supported Racing
17:31 Why Ditching the Hydration Pack Was a Huge Advantage
19:35 Aero Performance & Suit Design Details
21:21 Castelli's Aero Heritage & Innovation Story
23:12 Marginal Gains, Ryder Hesjedal & Performance History
23:48 Winter Riding, Future Testing & What's Next
24:18 “The Netflix of Cycling Clothing”
24:28 Outro
– HOST –
Søren Jensen, Global Marketing Manager at Castelli, has worked for this iconic brand since 2006. He usually rides backroads and dirt trails, testing new gear in the Italian Dolomites. If you can't find him there, check the Castelli Headquarters in Fonzaso. Connect: LinkedIn
SUBMIT YOUR QUESTION
If you want your questions to be answered on air, be sure to submit your questions by sending us a message on social media or by email to podcast@castelli-cycling.com
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