About SwimBikeRun.rocks
SwimBikeRun.rocks is built and run by Lukas Jufer, an age-group triathlete from Lake Zurich in Switzerland, with 20 long-distance finishes since 2015: 16 over the classic Ironman®-distance and Challenge courses, from Challenge Roth to Ironman Lanzarote, with a personal best of 9:52:43 at Ironman Italy Emilia-Romagna, and 4 Xtri races: Swedeman, Greek Hero on Corfu, Swissman and the ICON in Livigno, plus more than a dozen races over the half distance.
Why this site exists
Every one of those races began with the same questions: which swim split is realistic, what the bike costs the run, how much to eat and drink per hour and where to carry it. The answers used to live in spreadsheets that grew race by race. At some point the spreadsheets became formulas, the formulas became calculators, and the calculators went public, because the questions are the same for everyone on the start line.
Background
By training a biologist, with a master's degree in biology and later an MBA. The technology side goes back to a Commodore 64 in a child's bedroom in the 1980s: the fascination with making a machine compute something useful never left, and this site is its latest form.
How the site is built
The site is built by Lukas Jufer with Claude, Anthropic's AI assistant: the models, the code, the texts and the audit of the cited sources were developed in that collaboration. Every model names its sources, states its assumptions and is checked by an automated audit before a change goes live; The Science lays that out.
Long-distance results
Age-group results, not professional ones, and that is the point: the calculators are built for athletes who race with a job, a family and a limited training week.
| Year | Race | Time |
|---|---|---|
| 2015 | Ironman Switzerland, Zürich · Ironman®-distance | 11:06:08 |
| 2017 | Challenge Roth, Roth · Challenge | 10:14:36 |
| 2018 | Challenge Roth, Roth · Challenge | 10:05:21 |
| 2019 | Ironman Austria, Klagenfurt · Ironman®-distance | 10:19:34 |
| 2019 | Ironman Italy Emilia-Romagna, Cervia · Ironman®-distance | 9:52:43 |
| 2021 | Ironman Copenhagen, Copenhagen · Ironman®-distance | 9:58:51 |
| 2022 | Ironman Switzerland, Thun · Ironman®-distance | 11:08:25 |
| 2022 | Ironman Italy Emilia-Romagna, Cervia · Ironman®-distance | 10:01:10 |
| 2023 | Ironman Switzerland, Thun · Ironman®-distance | 11:15:50 |
| 2023 | Ironman Italy Emilia-Romagna, Cervia · Ironman®-distance | 10:27:39 |
| 2024 | Ironman Lanzarote, Puerto del Carmen · Ironman®-distance | 11:47:02 |
| 2024 | Ironman Switzerland, Thun · Ironman®-distance | 10:47:09 |
| 2025 | Ironman Lanzarote, Puerto del Carmen · Ironman®-distance | 11:46:12 |
| 2025 | Swedeman Xtreme Triathlon, Åre · Xtri | 13:31:18 |
| 2025 | Ironman Switzerland, Thun · Ironman®-distance | 10:43:58 |
| 2025 | Greek Hero Xtri, Korfu · Xtri | 13:39:39 |
| 2026 | Ironman Lanzarote, Puerto del Carmen · Ironman®-distance | 11:26:55 |
| 2026 | Swissman Xtreme Triathlon, Ascona to Kleine Scheidegg · Xtri | 15:52:21 |
| 2026 | Ironman Switzerland, Thun · Ironman®-distance | 11:02:38 |
| 2026 | ICON Xtri, Livigno · Xtri | 18:32:41 |
Independence
The site has no sponsors, no affiliate links, no advertising and no accounts; everything runs in your browser and no data leaves your device. The nutrition planner names brands only for their label values, and the presets are checked against the manufacturers' pages every month. Questions and corrections are welcome at info@swimbikerun.rocks; the imprint has the legal details.