intervals.icu vs Strava vs Garmin – Which Wins?

Strava Is a Social Network. Stop Using It as a Coaching Tool.

I've been using intervals.icu, Strava, Garmin Connect simultaneously for over a year now — all three, every single week, syncing to the same activities — and I want to tell you something that might sting a little if you've been paying for Strava Summit: Strava is Instagram for athletes. It is not a training tool. It never was. And the faster you make peace with that, the faster your numbers will actually move.

Here's what tipped me over the edge. I wanted to pull my full power data history into a third-party analytics tool. Simple enough request, right? It's my data. I paid for the device, I did the suffering, I generated every watt and heartbeat. Strava said: no. Their API is rate-limited to a trickle — 100 requests per 15 minutes, 1,000 per day — and they deliberately restrict what data fields third-party apps can access. Want your full power curve history in bulk? Good luck. Want another platform to read your raw .FIT files from Strava's servers? Not happening. It's your data, locked in their garden, fertilised with your subscription fee.

That's when I went all-in on intervals.icu. And I haven't looked back.

Strava's Dirty Little Secret: The API Is the Product

Let's be blunt about what Strava actually is from a business model perspective. They have 120+ million users generating an absolutely colossal dataset of human movement. That data has enormous commercial value for urban planning contracts, health research partnerships, and fitness brand analytics. Keeping your data inside their walls isn't a technical limitation — it's a strategic decision.

The API restrictions aren't there to protect you. They're there to protect their data moat. The moment your data flows freely to competitors or third-party platforms, Strava loses its lock-in. So they throttle, they restrict field access, and they make bulk exports painful enough that most people don't bother.

What Strava is genuinely great at: the social feed, Segments, the local cycling and running community, and the motivational dopamine hit of KOMs and kudos. Keep it for that. Use it like you use Instagram — for connection and a bit of competitive fun. Just stop pretending it's your coaching dashboard.

Garmin, Polar, Coros: Amazing Hardware, Siloed Software

Here's the other side of the problem. Your Garmin, Polar, or Coros device is a genuinely brilliant piece of kit. The sensors are accurate, the GPS is solid, and modern devices capture an almost absurd amount of data — power, pace, heart rate, HRV, ground contact time, vertical oscillation, respiration rate, body battery, sleep stages, SPO2, you name it.

But each of those brands wraps their data in their own ecosystem. Garmin Connect has its own Training Status and Body Battery algorithms. Polar has their Training Load Pro and Orthostatic Test. Coros has their Training Hub. They're all doing their own thing, with their own proprietary models, and none of them talk to each other coherently.

If you run with a Garmin and ride with a Polar HR strap (hypothetically), or you're a triathlete switching between sports and want one unified view of your training load across swim, bike, and run? Good luck getting that out of any single manufacturer's app. They're built to keep you in their lane, not to give you a complete picture.

For a deeper look at how training metrics actually fit together for endurance athletes, I wrote a deep dive into training metrics that's worth reading alongside this — the concepts in intervals.icu will make a lot more sense with that context.

intervals.icu: The Free Tool That Makes Everything Else Make Sense

intervals.icu was built by David Tinker, a software developer and cyclist who wanted what we all want: a proper analytics platform that treats you like an adult who can read a graph. It connects to Garmin Connect, Polar Flow, Coros, Wahoo, Suunto, TrainingPeaks, and yes — even Strava — via their APIs. Once it's syncing, it pulls your activities and gives you a unified dashboard that none of those native apps come close to matching.

Here's what I use it for every single week without exception:

• CTL/ATL/TSB (Fitness/Fatigue/Form): The PMC chart — Performance Management Chart — that TrainingPeaks charges you a monthly subscription to see, intervals.icu gives you for free. Your Chronic Training Load (fitness), Acute Training Load (fatigue), and Training Stress Balance (form/freshness) plotted over time. This alone is worth the switch.
• Power curve: See your best 1s, 5s, 1min, 5min, 20min, and 60min power across your entire training history. Colour-coded by time period. Watch it shift upward over a training block. It's viscerally motivating in a way that a Strava kudos notification just isn't.
• Intervals detection: Upload a workout with structured intervals and it auto-detects them, giving you lap-by-lap power, HR, pace, and cadence analysis. Brilliant for reviewing whether you actually hit your targets.
• Training load by sport: As a triathlete, I can see swim, bike, and run load on one chart, with separate fitness curves if I want them. No other free tool does this cleanly.
• Custom charts and fields: If your device records it, you can graph it. Respiration rate over a long ride? Temperature vs power output? Running power vs heart rate over 12 months? Yes, yes, and yes.

The free tier is genuinely, embarrassingly generous. The paid tier (around $2/month) adds some AI workout suggestions and a few extra features, but honestly, 90% of what makes this tool great is free.

One honest caveat: intervals.icu won't tell you what to do. It doesn't prescribe workouts. It doesn't give you a training plan. It's an analytics and visualisation tool, not a coaching platform. If you want prescribed training, you need a coach or something like TrainingPeaks paired with a plan. But for understanding your training load, spotting trends, and knowing when your form is peaking? Nothing touches it at this price.

If you're running all of this off a smart trainer setup, my winter indoor training setup guide covers how to get clean power data flowing into intervals.icu from your trainer — the quality of your indoor data matters more than you think for accurate CTL calculation.

The Head-to-Head Nobody Asked For But Everybody Needs

Feature	Strava	Garmin Connect	intervals.icu
Price	Free / ~$80/yr Summit	Free	Free / ~$24/yr Pro
PMC / Fitness Chart (CTL/ATL/TSB)	❌ No	⚠️ Basic only	✅ Full, free
Power Curve (all-time)	⚠️ 6 weeks max on free	❌ No	✅ Full history
Multi-sport training load	❌ No	⚠️ Garmin devices only	✅ Any device/platform
Interval analysis	❌ No	⚠️ Basic laps	✅ Auto-detect + deep stats
Custom metrics / graphs	❌ No	❌ No	✅ Anything your device records
Social / community features	✅ Best in class	⚠️ Limited	❌ Minimal
Segments / KOMs	✅ Best in class	❌ No	❌ No
Open data access / API	❌ Rate-limited, restricted	⚠️ Limited	✅ Import from everywhere
Training plan / coaching	❌ No	⚠️ Suggested workouts only	⚠️ Pro tier AI suggestions

Pros & Cons: intervals.icu Specifically

✅ Pros	❌ Cons
✅ Full PMC chart free — CTL, ATL, TSB that TrainingPeaks charges $19.99/month for. This alone justifies the switch.	❌ Steep learning curve — the interface is dense and not designed for beginners. Expect to spend a few evenings figuring it out.
✅ Device-agnostic — Garmin, Polar, Coros, Wahoo, Suunto, Strava, TrainingPeaks, direct .FIT upload. Whatever you're running, it connects.	❌ No prescriptive coaching — it tells you what happened and where your load sits, but not what to do next. You need a plan or a coach for that.
✅ Full power curve history — every best effort across your entire data history, not a rolling 6-week window.	❌ No social layer — if motivation comes from the community and kudos, you'll still need Strava running in parallel.
✅ Custom charts for any metric — if your device captures it, you can graph it. Genuinely any field in the .FIT file.	❌ One-person project — David Tinker built and maintains this largely solo. If he gets hit by a bus, the platform has a problem. That's a real risk for a tool you depend on.
✅ Free tier is genuinely complete — the $0 version is better than most paid alternatives for analytics.	❌ UI is functional, not beautiful — this is a tool built by a developer for developers and data-curious athletes. Don't expect Whoop's polish.

My Actual Setup (What I'd Recommend)

Here's the honest answer to "which one should I use?" — use all three, but know exactly what job each one is doing:

• Garmin / Polar / Coros native app: For live training guidance, structured workout execution, and device-specific features (HRV status, body battery, recovery advisor). Use it on your wrist, use it in the moment. Then leave it alone.
• Strava: For the community. For Segments. For the social layer that makes training feel connected to other humans. That's its job. Let it do that job and stop expecting more.
• intervals.icu: For every single analytical decision. Has my fitness actually gone up? Am I overreaching? What's my peak 20-minute power this year vs last year? Is my running load too high going into a race? This is where all of that lives.

The setup takes about 20 minutes — create your intervals.icu account, connect your Garmin/Polar/Coros or Strava account (even with the API restrictions, the basic sync works fine for pulling activities), and let it backfill your history. If you have years of data, the historical power curve that emerges is immediately addictive.

Verdict: Stop Paying Strava to Lock Your Own Data Away

If you're a triathlete or endurance cyclist who's serious about progression — not "I want to be a pro" serious, just "I want to understand what my training is actually doing" serious — intervals.icu is the single highest-value tool you're probably not using. It's free. It takes your data from wherever it lives and gives you a proper analytical view that no native platform comes close to. The PMC chart alone is worth signing up for.

Keep Strava. Keep your Garmin app. But add intervals.icu as the brain that sits on top of both of them. Your CTL will thank you.

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Are you using intervals.icu already, or are you still letting Strava play analytics tool with a dataset it refuses to share back with you — and if you've made the switch, what's the first chart that actually changed how you trained?