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About tfk — the5krunner

Hi, I’m tfk — also known as the5krunner, or simply “the 5k runner” — the pen name behind this blog.

the5krunner is an independent endurance sports technology publication covering GPS watches, fitness trackers, cycling computers and performance wearables. Founded and written by tfk, an international age-group triathlete with 20 years of hands-on testing experience.

Welcome to the5krunner.com, a blog born from my deep, occasionally unhealthy interest in running, triathlon, and sports technology. Over a decade ago, during my “5k running phase,” I began exploring training methods, gadgets, and nutrition to get faster. What started as a personal project soon evolved into a multi-sport platform for runners, triathletes, cyclists, and fitness enthusiasts — though you might have found me by searching for “5krunner” or “the 5krunner” along the way. the5krunner is not affiliated with and is entirely distinct from running training applications of similar names, such as couch-to-5K programmes.

My Story & Credentials

I’m a national age-group duathlon champion and a competitive multisport athlete with a knack for testing—and occasionally breaking—gear. My reviews are shaped by real race experience, not just lab specs.

Recent competitive highlights:

2024–25 National Duathlon Age-Group Champion
National championship qualifier winner
Several top-10 and top-5 finishes at ETU and ITU multisport finals
5K performances of 80% age-graded scores

That competitive background shapes everything I write: practical, tested, and athlete-focused. The kit I actually train, race and sleep with is listed on my Gear I use page.

What I Do

the5krunner.com is my platform for in-depth reviews, training tips, and sports tech insights. I spend tens of hours weekly researching, testing, and writing to create content that’s both engaging and evidence-based. My reviews focus on what matters most — performance, usability, and long-term value.

I strive for accuracy and balance, presenting both pros and cons while avoiding clickbait. Since adopting Grammarly in 2024, my writing has become more precise and technically correct, while keeping a natural tone and personality.

My Mission

This blog is a labour of love and my main professional focus since 2023, although I started it well over a decade ago. My mission is to help athletes make informed decisions about training and technology through honest, independent advice.

I’m financially independent from suppliers and purchase most of my own equipment (including Garmin devices) to ensure unbiased reviews. While I occasionally receive loaner products from PR agencies, my opinions are always my own — even when they ruffle feathers.

I aim to provide distinct perspectives — there’s little point in echoing the same mainstream opinions. Intelligent readers prefer diverse viewpoints so they can decide for themselves. That’s the kind of content I deliver.

Editorial Policy & Content Integrity

All articles on the5krunner.com are written and reviewed by me. Like every other media outlet, I use AI tools to assist with research or structure, but every post is written, edited, and fact-checked by humans before publication.

Each article is checked with Grammarly for originality, grammar, and AI consistency. I use Grammarly’s plagiarism and AI-detection tools to ensure the final content is unique and human-authored. Any flagged sections are rewritten or validated against primary sources; sometimes, it is impossible to alter them.

You can read more on my Editorial Policy page.

How It Works

the5krunner.com earns modest affiliate revenue through Amazon and other partners — far less than you might expect, considering the hours involved. The site attracts millions of annual page views, and your support helps it grow. Whether by reading, commenting, or using affiliate links, you keep this project alive (and my coffee mug full).

Get Involved

Join the conversation in the comments, email me at in**@*********er.com, or follow me on Twitter (X), Facebook, or other platforms using @the5krunner:

If you share my work, please credit and link back to the5krunner.com. Your engagement helps grow this community of endurance athletes and tech enthusiasts.

tfk (the5krunner) — National Duathlon Champion, GB Age-Group Athlete & Sports Tech Blogger

Small things I always use

Garmin 90-degree charging adapter: Charges your Garmin from any USB-C cable. Essential when travelling. I use one.
Body Glide: The blue anti-chafe stick swimmers and runners carry. I use it.
Speedo earplugs: Fewer ear infections and no cold-water dizziness. I use them.
Dryrobe Advance: My winter changing robe for open-water swims. I use one. A cheaper option is the AONYIYI changing robe.
Maurten: Race fuel that stays easy on the stomach. I use them.
Beet It Sport nitrate shots: Beetroot shots I take in the days before a race. I use them.
Garmin charging puck: The quickest way to top up before a session. I use one.
Injinji: Toe socks that stop rubbing, so you run more. I use them.
Ultimate toe protectors: Stop black toenails on long runs. They work. I use them.
Compressport R2 v2 calf sleeves: My calf sleeves of choice. I use them.
Cellucor C4: My pre-workout before hard sessions.
TPU tubes: Schwalbe Aerothan, Tubolito and Pirelli SmarTube. Light, tiny spares. I use all three.
G8 insoles: Adjustable insoles that are good. I use them.
Cycplus Cube: A 97g electric pump that gets a road tyre rideable in two minutes. I carry one. 5% off with code THE5KRUNNER.

Watches and sensors

Polar H10: My daily driver for waking HRV.
Polar Verity Sense: My backup arm-worn HR sensor.
Nomad bedside charger: Charges my iPhone and Apple Watch overnight. I use it, and many of their bands.
Train.Red: The best muscle oxygen sensor I’ve used.
Tymewear: Accurate heart rate and reliable ventilatory zones. I use it to pace endurance rides over an hour.
Garmin Forerunner 970: A pro-grade triathlon watch. I use this.
Apple Watch Ultra 4: My daily smartwatch. No phone needed on rides.
Garmin Fenix 9 Pro: I’ve just bought one.

On the bike

Continental GP5000 for everyday riding, and Aero 111 on the front for special occasions.
Helmets: Specialized S-Works Evade 3 for road riding, and Rudy Project Wing for TT-style races. I use both.
Ravemen FR300: A front light that mounts under your Garmin or Wahoo. I use one.
Wahoo TRACKR Radar: I use it on one bike and Varia on the other. They perform the same.
Garmin Varia RTL515: Radar that warns you of cars from behind. I use this model.
Wahoo ELEMNT Roam 3: The bike computer that’s easy to use. I use mine on most rides.
Favero Assioma Pro RS2: Accurate power pedals that swap easily between bikes. I use this model.

Home and indoor training

NPE Runn: Makes my basic treadmill smart, sending more accurate speed and distance to my watch and Zwift. I use it.
Google Wifi: Keeps Zwift connected in my pain cave. I use it.
Apple TV 4K: Zwift on the big screen. I use two.
Google Nest Doorbell (wired, 2nd gen): My video doorbell, running in both Google Home and Apple Home. I use it.

Health, recovery and sleep

FreeStyle Libre 3 Plus: Shows how my blood sugar responds to diet.
hDrop: Measures my sweat loss in summer and indoors.
Fourth Frontier Zone: Checks my heart under load in hard sessions.
Oura Ring 5: My partner’s recovery tracker of choice.
Eight Sleep: A cooling mattress cover my partner and I use nightly.

Reader-Powered Content

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Written by real people, with AI assistance. Fact-checked and verified for originality. See the Editorial Policy. FTC: Affiliate Disclosure — some links pay commission. As an Amazon Associate, I earn from qualifying purchases.