trace - what used to take several apps and a coach, in one place

[lukasfromtrace]

Hi everyone,

I'm Lukas, an ambitious cyclist, and I've spent the last half year building trace, the final months of it in beta. It went live on the App Store earlier this month, so I'd like to introduce it here.

Deep analysis of your training and health data, a plan that adapts to your everyday life, and an AI coach you can ask anything. What you used to need several apps and a coach for now sits in one app: trace



What it computes:

• Readiness - from HRV, resting HR, sleep and training load, every factor shown against your own baseline
• Training load - CTL, ATL and TSB, plus monotony and ramp warnings
• Endurance - durability, aerobic efficiency, VO2max and fitness age
• Heat acclimatization - estimated from your normal sessions
• Cycling - Critical Power and W' estimated from your everyday rides, power curve, W'bal, rider profile
• Climbs - detection, VAM, pacing, all your ascents compared
• Running - critical pace, HR recovery, training effect
  

Beyond the numbers, for cycling and running:

• Training plans with structured workouts that react to how you actually train, pushed straight to Wahoo, Suunto, Hammerhead or the Apple Watch
• Workout report after each session: plan vs. execution
• Race preparation - course simulation, race prediction and pacing for your goal event
• Fuelling - carb and fluid targets in grams and millilitres, for training and race day
• AI coach that knows your full history and answers questions about it
  

One thing that matters to me: every metric above is computed deterministically, there is no language model anywhere in that path. The AI sits on top: it explains your values, answers questions, writes the post-session report, and drafts the training and meal plans. Even there it works inside computed limits: the engine sets periodisation, weekly TSS and fuelling targets, and every generated week is checked against them.

Getting your data in: Apple Health, Wahoo, Polar, Suunto and Hammerhead connect directly, and you can import FIT, TCX and GPX files. Strava and Garmin come in through intervals.icu, which trace reads in full: activities, streams and wellness. The only thing it writes back there is planned workouts into your calendar.

Your data: hosted in the EU, full export any time, account deletion right in the app.

Platforms: the recent months went into the iOS app, which is where trace feels most at home. On the desktop, the web version at usetrace.de gives you the full feature set on a big screen, and polishing its presentation is what comes next. A native Android app is in the works.

Pricing: there's a permanent free tier. The full analysis is €6.99/month; plans, race preparation and the full coach are €12.99/month. Both 20% less on yearly billing, both with a 14-day free trial.

Give it a try.
App Store: https://apps.apple.com/app/id6770614306
Web: https://usetrace.de

I'll be in the comments, happy to go into detail on how any of the metrics are computed. One thing I'm curious about: what does your current setup not tell you that you wish it did?

[Flowrider]

Hi @lukasfromtrace. Looks like an exceptional, in-depth app! Great effort.

I ride mountain biking 90% of the time and lose reception with most apps (including Strava) in the areas I ride. Apps that run off GPS give me the best consistency.

Does yours work off GPS or a local telecommunication network?

[meamoantonio]

Impressive stuff @lukasfromtrace how is heat acclimation computed here? What’s the data input?

[lukasfromtrace]

(08-25-2026, 07:00 PM)Flowrider Wrote:  Hi @lukasfromtrace. Looks like an exceptional, in-depth app! Great effort.

I ride mountain biking 90% of the time and lose reception with most apps (including Strava) in the areas I ride. Apps that run off GPS give me the best consistency.

Does yours work off GPS or a local telecommunication network?

Hi @Flowrider . Thanks, that means a lot to hear.

Unfortunately the app itself cannot be used to record activities yet. I will definitely take your point on board though and think about adding that feature in the near future.

If you have a fitness watch or a bike computer, you can import your activities into trace directly.

Cheers,
Lukas

[lukasfromtrace]

(08-25-2026, 08:57 PM)meamoantonio Wrote:  Impressive stuff @lukasfromtrace how is heat acclimation computed here? What’s the data input?

Thanks a lot @meamoantonio . Good question, happy to go into it.

Every outdoor ride or run feeds into it. For each session trace takes the GPS start point and the time of day and pulls the actual weather from Open-Meteo, temperature and humidity, averaged over the duration. The device temperature is only a fallback, since a head unit sensor sits in the sun, picks up your own body heat and carries no humidity at all.

From temperature and humidity it builds a heat index, and everything above 22 °C counts. That excess, times the duration, times the intensity of the session including heart rate drift within it, gives a heat dose. Those doses run through an asymmetric build and decay model: a solid hot session moves the number noticeably, two days without heat are free, after that it fades by about 3 percent a day. The 0 to 100 scale is a guideline, not a measurement. The model follows Périard, Racinais and Sawka (2015).

If you train with a CORE sensor, that replaces the weather proxy. trace reads core temperature straight out of the .fit file and measures the area above 38.5 °C, damped by skin temperature so that simply being warm in a stuffy room does not register as a heat stimulus. In that mode indoor sessions count too.

For completeness: the heat index is shade based, so solar radiation is not in there, and without a sensor the outside temperature stays a proxy for what your body actually did. That is exactly why the CORE path exists.

[SPINMAN]

(08-25-2026, 06:04 AM)lukasfromtrace Wrote:  Hi everyone,

I'm Lukas, an ambitious cyclist, and I've spent the last half year building trace, the final months of it in beta. It went live on the App Store earlier this month, so I'd like to introduce it here.

Deep analysis of your training and health data, a plan that adapts to your everyday life, and an AI coach you can ask anything. What you used to need several apps and a coach for now sits in one app: trace



What it computes:

• Readiness - from HRV, resting HR, sleep and training load, every factor shown against your own baseline
• Training load - CTL, ATL and TSB, plus monotony and ramp warnings
• Endurance - durability, aerobic efficiency, VO2max and fitness age
• Heat acclimatization - estimated from your normal sessions
• Cycling - Critical Power and W' estimated from your everyday rides, power curve, W'bal, rider profile
• Climbs - detection, VAM, pacing, all your ascents compared
• Running - critical pace, HR recovery, training effect
  

Beyond the numbers, for cycling and running:

• Training plans with structured workouts that react to how you actually train, pushed straight to Wahoo, Suunto, Hammerhead or the Apple Watch
• Workout report after each session: plan vs. execution
• Race preparation - course simulation, race prediction and pacing for your goal event
• Fuelling - carb and fluid targets in grams and millilitres, for training and race day
• AI coach that knows your full history and answers questions about it
  

One thing that matters to me: every metric above is computed deterministically, there is no language model anywhere in that path. The AI sits on top: it explains your values, answers questions, writes the post-session report, and drafts the training and meal plans. Even there it works inside computed limits: the engine sets periodisation, weekly TSS and fuelling targets, and every generated week is checked against them.

Getting your data in: Apple Health, Wahoo, Polar, Suunto and Hammerhead connect directly, and you can import FIT, TCX and GPX files. Strava and Garmin come in through intervals.icu, which trace reads in full: activities, streams and wellness. The only thing it writes back there is planned workouts into your calendar.

Your data: hosted in the EU, full export any time, account deletion right in the app.

Platforms: the recent months went into the iOS app, which is where trace feels most at home. On the desktop, the web version at usetrace.de gives you the full feature set on a big screen, and polishing its presentation is what comes next. A native Android app is in the works.

Pricing: there's a permanent free tier. The full analysis is €6.99/month; plans, race preparation and the full coach are €12.99/month. Both 20% less on yearly billing, both with a 14-day free trial.

Give it a try.
App Store: https://apps.apple.com/app/id6770614306
Web: https://usetrace.de

I'll be in the comments, happy to go into detail on how any of the metrics are computed. One thing I'm curious about: what does your current setup not tell you that you wish it did?

Definitely south a look. Thanks

---

I don't mind my Garmin watch metrics and Bryton on board computer uploading to Strava and Relive, but this is worth a look. Thanks

[lukasfromtrace]

Definitely south a look. Thanks

---

I don't mind my Garmin watch metrics and Bryton on board computer uploading to Strava and Relive, but this is worth a look. Thanks
[/quote]

Thanks @SPINMAN , glad you want to give it a try! If anything comes up along the way, just ask here or drop me a PM.

[SPINMAN]

(08-27-2026, 01:29 PM)lukasfromtrace Wrote:  Definitely south a look. Thanks

---

I don't mind my Garmin watch metrics and Bryton on board computer uploading to Strava and Relive, but this is worth a look. Thanks

Thanks @SPINMAN , glad you want to give it a try! If anything comes up along the way, just ask here or drop me a PM.
[/quote]

👌👍

[GirishH]

@lukasfromtrace , I too was wondering about heat acclimation and your app.

For example, I’m currently in Leh, Ladakh, India, where I’m unusually thirsty and dehydrated regardless of whether I drink 2 liters or 8 liters of water. So, before I embark on my bikepacking trip, I’m trying to acclimatize to the heat by training around noon or in the middle of the afternoon, say 2–3 p.m.

Basically, I’m trying to “heat acclimatize” before venturing deeper into this high-altitude desert in the Himalayas.

So I was curious about your app’s heat-acclimation feature.

I use a Garmin watch and Strava. I’m curious whether either of them records heat-related data that your app can pull in. Or would I need to have your app running while I’m cycling or running?

(08-26-2026, 07:56 AM)lukasfromtrace Wrote:  

(08-25-2026, 08:57 PM)meamoantonio Wrote:  Impressive stuff @lukasfromtrace how is heat acclimation computed here? What’s the data input?

Thanks a lot @meamoantonio . Good question, happy to go into it.

Every outdoor ride or run feeds into it. For each session trace takes the GPS start point and the time of day and pulls the actual weather from Open-Meteo, temperature and humidity, averaged over the duration. The device temperature is only a fallback, since a head unit sensor sits in the sun, picks up your own body heat and carries no humidity at all.

From temperature and humidity it builds a heat index, and everything above 22 °C counts. That excess, times the duration, times the intensity of the session including heart rate drift within it, gives a heat dose. Those doses run through an asymmetric build and decay model: a solid hot session moves the number noticeably, two days without heat are free, after that it fades by about 3 percent a day. The 0 to 100 scale is a guideline, not a measurement. The model follows Périard, Racinais and Sawka (2015).

If you train with a CORE sensor, that replaces the weather proxy. trace reads core temperature straight out of the .fit file and measures the area above 38.5 °C, damped by skin temperature so that simply being warm in a stuffy room does not register as a heat stimulus. In that mode indoor sessions count too.

For completeness: the heat index is shade based, so solar radiation is not in there, and without a sensor the outside temperature stays a proxy for what your body actually did. That is exactly why the CORE path exists.

[lukasfromtrace]

(08-30-2026, 10:30 AM)GirishH Wrote:  @lukasfromtrace , I too was wondering about heat acclimation and your app.

For example, I’m currently in Leh, Ladakh, India, where I’m unusually thirsty and dehydrated regardless of whether I drink 2 liters or 8 liters of water. So, before I embark on my bikepacking trip, I’m trying to acclimatize to the heat by training around noon or in the middle of the afternoon, say 2–3 p.m.

Basically, I’m trying to “heat acclimatize” before venturing deeper into this high-altitude desert in the Himalayas.

So I was curious about your app’s heat-acclimation feature.

I use a Garmin watch and Strava. I’m curious whether either of them records heat-related data that your app can pull in. Or would I need to have your app running while I’m cycling or running?

(08-26-2026, 07:56 AM)lukasfromtrace Wrote:  

(08-25-2026, 08:57 PM)meamoantonio Wrote:  Impressive stuff @lukasfromtrace how is heat acclimation computed here? What’s the data input?

Thanks a lot @meamoantonio . Good question, happy to go into it.

Every outdoor ride or run feeds into it. For each session trace takes the GPS start point and the time of day and pulls the actual weather from Open-Meteo, temperature and humidity, averaged over the duration. The device temperature is only a fallback, since a head unit sensor sits in the sun, picks up your own body heat and carries no humidity at all.

From temperature and humidity it builds a heat index, and everything above 22 °C counts. That excess, times the duration, times the intensity of the session including heart rate drift within it, gives a heat dose. Those doses run through an asymmetric build and decay model: a solid hot session moves the number noticeably, two days without heat are free, after that it fades by about 3 percent a day. The 0 to 100 scale is a guideline, not a measurement. The model follows Périard, Racinais and Sawka (2015).

If you train with a CORE sensor, that replaces the weather proxy. trace reads core temperature straight out of the .fit file and measures the area above 38.5 °C, damped by skin temperature so that simply being warm in a stuffy room does not register as a heat stimulus. In that mode indoor sessions count too.

For completeness: the heat index is shade based, so solar radiation is not in there, and without a sensor the outside temperature stays a proxy for what your body actually did. That is exactly why the CORE path exists.

Hi @GirishH , good question.

You do not need anything running while you ride. trace reads the finished activity afterwards: the GPS start point plus start time gives the real temperature and humidity for that spot, averaged over the session, and everything above 22 °C heat index counts as exposure, weighted by how hard you went. Out of that comes a 0 to 100 acclimatization score that builds fast and fades about 3 % a day once the heat stops, so you can see how much adaptation you have built up, and how much of it you would still have on the day you roll out on the bikepacking trip.

For your setup the path is Garmin to intervals.icu (free, syncs by itself), then trace connects to intervals. No Strava needed. And since the score is computed from weather data, it backfills your whole history the moment you connect. That is the nice part for you: the Ladakh block you have already put in shows up straight away as a curve instead of a fresh start from zero. Any runs you throw in count towards the same curve too.

One thing worth knowing for Leh: the heat index is a shade value, so in that high-altitude sun and dry air the score reads on the conservative side. The real stimulus is probably a bit higher than what the number shows. It tracks the heat adaptation, and altitude is a separate one you are building alongside it.

Happy to compare notes once you are set up, that is a rare data set.

[Flowrider]

I've probably used 9 or 10, maybe more, apps and have settled on the Ride with GPS app. For purely tracking purposes how does your app compare?

[Jesper]

Question: why waste your money?

Cycling does not require applications or coaches. What it does take to cycle is revealed below so save your money. Generations of cyclists have done it without any need for electronics of any nature, nor special foods.

No offense, but rely on your intelligence. Ignore marketing (they just want your money). Marketing and gimmicks do not make you a better cyclist; but riding more miles under increasingly difficult conditions does.

Shut if off, leave it at home, ride with freedom and complete abandonment; or be a slave to marketing.

Answer: What you do need: a functioning cycle, air, water, real food (nothing processed), and sleep. That is it. Save your money.

---

Name one professional racer that uses your product and has had podium success? I assume you tested your fluff with someone of import that proves to others that your product is worth a darn.

Racer name please:________________Podium finishes___
Race names____________________________________________
You do realize that today's cyclists think they need pro products whether it helps them or not; but it helps to name drop.

[Flowrider]

Interesting. I ride in a couple of riding groups and asked for some feedback on what you wrote.

The general consensus was that we're all different, and the majority said that having app information and feedback after their rides lets them know where they are health-wise, and that after reading their ride information, it gave them a sense of accomplishment.

Also said the free version of most apps gave them adequate information