A WH-C06 BLE crane scale costs about $30 on Amazon. It samples at 8 Hz — eight force readings per second.
That sample rate gives you a perfectly honest time-under-tension number. It gives you a perfectly honest impulse number. It gives you a perfectly honest set TUT total.
It also gives you a wildly dishonest rate of force development number, if anyone tries to compute it. And a misleading tempo reading on slow eccentrics.
Same sensor. Same data. Same software. Some metrics survive the under-sampling; some don’t. Knowing which is the entire game.
What sensor honesty actually is
Every metric tensr surfaces has a relationship to sample rate:
| Metric class | 8 Hz (C06) | 80 Hz (Tindeq, C100 retrofit) | Why |
|---|---|---|---|
| Force samples / impulse / TUT | ✅ | ✅ | Integrated; under-sampling smooths out |
| Peak force / average force | ✅ | ✅ | Aggregate over many samples |
| Rep segmentation | ⚠️ | ✅ | Edge detection blurs at 8 Hz |
| Tempo (eccentric/concentric duration) | ⚠️ | ✅ | 125 ms per sample misleads on slow tempos |
| Effective rep count | ⚠️ | ✅ | Inherits rep-segmentation noise |
| RFD (0–200 ms slope) | ❌ | ✅ | Slope needs sub-200 ms resolution |
| Time to peak (TTP) ms-precision | ❌ | ✅ | ms-precision impossible at 125 ms/sample |
| Bilateral timing offset (ms) | ❌ | ✅ | Same as TTP |
| Form-shape variance | ⚠️ | ✅ | Curve shape gets pixelated |
| Bilateral symmetry (impulse-based) | ✅ | ✅ | Integrated; rate-tolerant |
This isn’t a hardware sales chart. It’s the contract: the app will show you metrics where the data supports them, and hide them — not approximate them — where it doesn’t.
Why it matters
Most fitness data lies politely. A wrist heart-rate that’s actually a wrist accelerometer plus a confident algorithm. A “calorie burn” estimate built on assumptions about your metabolism it has no way to know. A “VO2max” reading inferred from heart rate variability.
The lies are useful, sometimes. They give you a number where measuring the real thing would require lab equipment. The honesty problem is that the user can’t see which numbers are measured and which are inferred.
tensr commits to a different stance: when the sensor can’t support a metric, the metric isn’t shown. When the sensor can support it with caveats, the caveat is on screen next to the number — not buried in documentation.
The user-facing rule: if it’s on screen, it’s real, at this sample rate. Not “real in general.” Not “real if you upgrade.” Real, on the sensor you’re using right now.
What to track together
The sensor-health metrics are best read as one “is my data trustworthy?” view, distinct from the training metrics.
| Metric | What it tells you |
|---|---|
| Effective sample rate | What rate is the sensor actually delivering, vs its spec? |
| Signal noise floor | Standard deviation during a 10-second rest — your equipment’s signature |
| Drift | Has the zero baseline moved across the session? |
| Connection quality | % of expected samples received |
| Sensor latency | Inter-sensor offset (relevant for two-sensor work) |
| Battery level | Practical concern for long sessions |
Pair this with the per-metric honesty matrix. The matrix tells you which numbers to trust; the device-health view tells you whether your sensor is performing to its spec on this specific session.
What gear it needs
N/A — this post is about gear.
But here’s the practical takeaway for shopping: what you’re paying for in the higher-rate sensors is the honesty matrix, not the metrics themselves. Most lifters don’t need RFD, sub-second tempo precision, or ms-resolution timing offset. The ones who do — strength athletes, return-to-play rehab, elite power sport — find the upgrade pays itself back instantly.
For everyone else: the C06 is a perfectly good entry point. Honest TUT. Honest impulse. Honest set decay. Honest weekly volume. Honest bilateral symmetry on impulse. That’s most of the catalog.
What to do tomorrow
Pair your sensor for the first time. Let it sit on the bench for 10 seconds while you adjust your headphones. Look at the noise floor on screen.
That number is your equipment’s signature — the standard deviation of force readings when nothing is touching the sensor. A clean sensor reads under ~1 N noise floor. A noisier one reads 3–5 N. A failing one reads 10+ N.
Now check the effective sample rate against the device spec. A C06 should report ~8 Hz; if it’s 4 or 5, your Bluetooth connection is choppy and the metrics inherit that noise.
Two checks. 30 seconds. Now you know what your data looks like at rest, and what to expect during work.
A specific note on shopping: if a sensor’s marketing claims aren’t backed by a published sample rate spec, treat the missing number as a feature absence. “Bluetooth force scale” with no sample rate listed is exactly the kind of detail that does more for you to know than not know.
The C06 is honest about what it is. So is the Tindeq. Most other things in this category aren’t, yet.