> For the complete documentation index, see [llms.txt](https://docs.velogicfit.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.velogicfit.com/section-02-using-velogic-studio/marker-reflectivity-issue.md).

# Marker reflectivity issue

Some VF Tape rolls are not fully retro-reflective. How to identify the affected marker, what to do about it, and what Velogic is doing to fix it.

Some rolls of Velogic marker tape (VF Tape) produced from early 2026 onwards are not fully retro-reflective. If markers are dropping out of detection for you, this page is the single place that explains what is happening, what we are doing, and what you can do right now to keep fitting.

If you are troubleshooting detection generally and have not yet ruled out camera setup, lighting or the number of markers configured, start with [Troubleshooting marker detection](/section-02-using-velogic-studio/troubleshooting-marker-detection.md) and then come back here.

## What the issue is

The retro-reflective layer on the marker dots is applied during manufacture. On some production runs it was not applied correctly, so the dots are **reflective but not properly retro-reflective**.

The practical difference is angle. A properly retro-reflective dot sends infrared light (from the camera's laser) straight back to the camera from a wide range of angles. An affected dot only does that when it is close to square-on to the camera. As soon as it sits at an angle, the light bounces away instead of coming back, the camera sees nothing there, and the marker drops out.

What that looks like in a fit:

* Markers drop out intermittently or just aren't ever detected
* The markers that sit on angled surfaces go first: shoulder, ankle, heel and toe
* The detection quality indicator shows red instead of green
* The skeleton flickers, or does not form at all
* Occasionally the software latches onto a reflection somewhere else (a shiny part of the frame) instead of the real marker, which can show up as sudden phantom movement

Three things worth knowing:

* **It is not your camera and it is not the software.** Nothing you change in Velogic Studio will fix an affected dot.
* **It varies roll to roll, not just batch to batch.** Two rolls from the same box can behave differently.
* **It's usually just some bad dots on a roll.** We have not seen a roll where no marker works. Most rolls in circulation have no issues at all, and on an affected roll it is a proportion of the markers that fail rather than all of them.

## What we are doing about it

* We have confirmed the defect with our manufacturer, who is working through it with the maker of the reflective material.
* Future production runs will carry lot numbers so rolls can be traced back to a batch.
* We replace affected tape at no cost, including tape bought through a distributor.
* Longer term, we are moving the markers onto a higher grade retro-reflective film from one of the two specialist manufacturers of that material, rather than relying on the current print process.

Being straight with you: the most recent batch is much better but is not perfect, and we have seen the occasional poor roll in it. That is exactly why the first step below is to try another marker, then another roll, rather than waiting weeks for a shipment that may not be any better.

**Please tell us if you are affected.** It helps us size the problem and trace which shipments went where: [report it using this short form](https://forms.cloud.microsoft/r/DHig4Lt4Y2), or email <support@velogicfit.com>.

## What you can do about it

Work through these in order. Most people are sorted by step 4.

### Step 1: Find out which marker is the problem

When Velogic Studio cannot build a valid skeleton from your 7 (or 8) markers, it falls back to showing you a **red dot** for each marker it *did* find.

So: get the rider pedalling and watch the red dots. Count them, and look for the gap.

* A marker that gets no red dot is not being detected at all
* A marker whose red dot flickers on and off through the pedal stroke is marginal
* Note *which* position it is. Shoulder, ankle and toe/heel are the usual suspects, because they sit at an angle to the camera

Expect to be dealing with **individual bad markers, not a dead roll**. We have not seen a roll where nothing works. Even on an affected roll most markers are fine, and it is the proportion of duds that varies. So the fix is usually to replace the one marker that is misbehaving and carry on.

If every marker gets a steady red dot but no skeleton forms, that is a different problem. See [Troubleshooting marker detection](/section-02-using-velogic-studio/troubleshooting-marker-detection.md).

### Step 2: Check how the rider is framed in the camera

Before you touch the markers, check the camera view. A marker near the edge of the frame is unreliable no matter how good it is.

* The rider should be **vertically centred** in the camera's field of view
* The **shoulder marker at the top and the toe marker at the bottom** both need clear space between them and the edge of the frame. A foot sitting right on the bottom edge of the view is the most common version of this
* The camera should be no more than about 8 feet (2.4m) from the plane of the bike, or the dots get too small to recognise

See [Setting up the fit area](/section-01-getting-started/setting-up-fit-area.md) if you need to re-position.

### Step 3: Rule out placement before you blame the marker

A badly placed good marker looks exactly like a well placed bad marker. Check placement next, because it costs nothing.

Common placement causes of dropout, even for good markers:

* **On a curved surface.** This is the big one, and the heel is the worst offender. A marker bent around a curve points most of its surface away from the camera. Find the flattest spot that still sits on the landmark.
* **Too near an edge.** A heel or toe marker wrapped around the edge of the shoe, or right on the sole line, presents almost nothing to the camera. There should be visible tape margin around the dot, especially below it.
* **Too much angle to the camera.** The shoulder marker placed too high (up on the acromion rather than on the humeral head) tips away from the lens. Same for a wrist marker rotated inwards, or an ankle marker that has crept round the back.
* **On loose clothing.** The shoulder marker in particular needs to be on tight-fitting fabric. On a t-shirt or a loose jersey the marker creases, which breaks up the reflective surface, and it shifts around as the rider moves. Ask the rider to change into something closer-fitting if you can.
* **Partly covered.** A jersey hem over the hip marker, a sock riding up over the ankle, a watch strap, a bunched shorts leg.

Move the marker to the correct position, following [Joint marker placement](/section-02-using-velogic-studio/joint-marker-placement.md), and watch the red dots again.

One caution: **moving the shoulder marker down onto the upper arm does make it detect better, but it also changes what is being measured.** Treat it as a last resort, not a fix.

### Step 4: Replace the marker, then change roll if you need to

If the framing and the placement are both right and the marker still drops out, work through this in two stages.

**First, replace that single marker with another one from the same roll.** Most of the time this is all it takes, because you are dealing with the occasional dud rather than a bad roll.

**Then, if the replacement is no better, put that roll aside and open a new one.** As a rule of thumb: if more than about four of your last twenty markers have given trouble, stop using that roll. One or two duds in twenty is worth living with for now; just swap out the individual markers as they come up.

Keep using the rolls you already have rather than waiting for a shipment. The defect varies roll to roll, even within a single box, so you very likely already have good rolls on the shelf. Older green tape (as opposed to the newer blue pre-cut squares) is generally good if you still have some.

Please do not try to judge a roll as good or bad by looking at it. We have internal tests for that, but they need controlled lighting and a known-good roll side by side, and they are genuinely unreliable in other conditions. Judging by eye leads to good rolls being thrown away and bad rolls being kept. Let the software tell you: apply the marker and see whether the red dot is steady.

### Step 5: \[Optional] Angle the marker towards the camera

If a particular position keeps failing even with fresh tape, help the dot face the lens.

* **Double up.** Stick a second marker (or a folded piece of tape) underneath one edge of the marker, so the dot is tilted towards the camera rather than lying flat against a sloping surface. Shoulders and heels benefit most.
* **Build a small wedge.** For the shoulder specifically, some fitters use a small angled backing held on a velcro band to hold the marker square to the camera.

This is a workaround, not a repair. Keep the dot centred on the same anatomical landmark; tilting is fine, moving is not.

### Step 6: Apply a truly retro-reflective sticker over the top

If a marker still will not detect, you can put a genuinely retro-reflective sticker **on top of** the Velogic dot. This is a little DIY but works really well.

**Always apply it centred on an existing Velogic marker, never directly on the rider's skin.** These stickers use a general-purpose permanent adhesive which is not rated for skin contact. The Velogic tape underneath is the skin-safe layer, and it also gets your placement right.

Where to get suitable stickers:

* **In Europe:** silver retro-reflective geocaching reflectors are sold pre-cut at our marker size. Reflecto GmbH sell them at [reflexfolie.de](https://www.reflexfolie.de/geocaching-reflektoren-silber-01180011) in 20mm (and 10mm) diameter. This is a known-good fix in use by some of our higher-volumen fitters.
* **Everywhere else, including the USA:** we have not yet found a pre-cut sticker outside Europe that we are confident recommending, because retro-reflective material varies enormously between products that look identical on the shelf. Make your own instead. [Reusable marker squares cut from a safety vest](#do-it-yourself-reusable-marker-squares-from-a-safety-vest) use the right grade of material, cost almost nothing, and you can buy the makings almost anywhere.

### Step 7: Tell us, and get replacement markers

Email <support@velogicfit.com> or [fill in the form](https://forms.cloud.microsoft/r/DHig4Lt4Y2). We replace affected tape at no cost, as long as we can prove that it's from an affected batch; whether you bought from us or through a distributor. Tell us when you ordered and from whom, which helps us trace the batch.

Three things that help us a lot if you can include them:

* **Which marker positions held up and which dropped out.** Shoulder, hip, ankle, toe, heel. That tells us more about the material than any bench test we can run here.
* **A screenshot** of the red dots when a marker is failing.
* **How many rolls out of the box turned out to be bad.** Keep those rolls to one side rather than throwing them out, and once you have worked through the box, tell us the count. We already have plenty of bad rolls to test here, so we do not need yours. What we are short of is how much of a batch is affected, and only you can tell us that.

Once new markers arrive, you do not have to throw out your existing stock. Most fitters keep using what they have and use the new rolls to replace the occasional marker that misbehaves.

## Do it yourself: reusable marker squares from a safety vest

If you are between shipments, or you just want a set of known-good markers for the positions that keep giving trouble, you can make your own from the reflective banding on a hi-vis safety vest. They cost almost nothing, they are reusable, and you can prepare a batch in advance and keep them in your kit.

They are not a Velogic product and we do not officially support them, but the material is sound. When we tested safety-vest reflective material against our own markers, a 20mm square of it detected as reliably (and sometimes even more reliably) as a standard 25mm Velogic dot.

### 1. Get the right vest

In the USA the [3M Day/Night Safety Vest 94616H1-DC](https://www.amazon.com/dp/B00FELOJI4) is a good one to start from, at around $12. Its specification names the reflective trim as 3M Scotchlite 8906, which is exactly the grade you want, and it is certified to ANSI/ISEA 107 Class 2.

If that one is unavailable, or you are outside the USA, here is what to look for on any vest:

* **Silver banding, not coloured.** Silver retro-reflective trim is roughly three times brighter than the fluorescent orange or lime versions. If a vest has a combined orange and silver stripe, only the silver part is useful to you.
* **A certification printed on the label:** ANSI/ISEA 107 in the USA and Canada, EN ISO 20471 in Europe, AS/NZS 1906 or AS/NZS 4602 in Australia and New Zealand. This matters more than the brand, because those standards set a minimum retro-reflective performance and it is checked on the finished garment.
* **A named material.** "3M Scotchlite" or "ORALITE" on the label is a good sign. If a part number is given, the 3M 8906, 8910, 8912, 8925, 9910 and 9920 fabrics are all the right type.
* **Banding at least 50mm (2 inches) wide**, so you have margin to cut 20mm squares out of it.
* **Avoid** anything sold as vehicle, trailer or road sign tape, described as prismatic or honeycomb, or labelled "engineer grade". Those are a different and much dimmer type of retro-reflective material at the angles we care about, however bright they look in a torch beam.

You will also need a sharp craft knife or scalpel, a pair of scissors, a marker pen, and a roll of **electrical tape**.

### 2. Remove the banding from the vest

The banding is sewn on, not glued, so it lifts off cleanly if you cut the thread rather than the fabric.

Work along the stitching with the tip of a sharp knife, cutting the thread itself and easing the banding away as you go. Take your time. The aim is to come away with the reflective strip intact and undamaged; if you cut into the banding you lose usable material, and a nicked edge frays.

![Cutting the stitching along the edge of the reflective banding on a lime hi-vis vest to release the strip](https://11145950-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FjxwtZYYk0lvusnMTywNR%2Fuploads%2Fgit-blob-b5e907b48e0d1c1314bfe9a3206c3869593b9b69%2Fmarker-reflectivity-vest-removing-banding.jpg?alt=media)

### 3. Mark the back before you cut

**This step is worth doing and easy to skip.** Once the strip is cut into small squares it becomes surprisingly hard to tell which face is which, and a square applied back-to-front will not be detected at all.

The retro-reflective face usually looks **darker** than the back in ordinary room light, which is a useful clue but not a reliable one once you are working quickly at a fit.

So before you cut anything, turn the strip over and **draw lines across the back with a marker pen**. Cover the whole strip, so that every square you cut out of it carries an obvious pen mark on its back. Then you can tell at a glance which way round a square goes, however small the piece.

![The back of the removed strip covered in marker pen lines and squiggles, so that every square cut from it carries a mark](https://11145950-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FjxwtZYYk0lvusnMTywNR%2Fuploads%2Fgit-blob-bd4b9fa43ec2188dce8d6d9b25029e171234e7b9%2Fmarker-reflectivity-vest-marking-back.jpg?alt=media)

### 4. Cut into 20mm squares

Cut the strip into squares about **20mm** across.

Square is fine. Velogic Studio finds the centre of a marker geometrically and makes no assumption about its shape, so a 20mm square is detected just as reliably as our 25mm circle. Do not go much below about 15mm, or the camera will start to struggle at distance.

![Five squares cut from the strip with scissors, pen-marked backs facing up](https://11145950-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FjxwtZYYk0lvusnMTywNR%2Fuploads%2Fgit-blob-6f72b9e8457d7809ec36e2fa5b7f7f821834110b%2Fmarker-reflectivity-vest-cut-squares.jpg?alt=media)

### 5. Add a tape loop to each square

Cut off a short piece of electrical tape and join the ends into a **loop with the sticky side facing outwards**, then press it onto the marked back of a square. You now have a square with its own double-sided pad.

Electrical tape suits this better than most: it grips firmly, it stretches slightly so it sits flat on a curved surface, and it peels off again without leaving residue.

Do a batch of these in advance and keep them in your kit, and applying one during a fit takes a couple of seconds.

![A finished square with a loop of tape stuck to its pen-marked back, forming a double-sided pad](https://11145950-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FjxwtZYYk0lvusnMTywNR%2Fuploads%2Fgit-blob-a8a017467c29b3ed551170eee3be58ff4b18e97c%2Fmarker-reflectivity-vest-tape-loops.jpg?alt=media)

### 6. Apply over the top of the Velogic dot

Place your normal Velogic markers on the rider as usual. When one of them will not detect, press a prepared square straight over the top of it, **reflective side out**, with the pen-marked side against the dot.

**Always apply it over an existing Velogic marker, never directly on the rider's skin.** The vest fabric and the tape adhesive are not intended for skin contact, whereas the Velogic tape underneath is. Applying over the dot also keeps your landmark placement honest, so the fit data stays comparable with your other fits.

Afterwards, peel the squares off, wipe them clean, and reuse them.

![A prepared square pressed down over a marker, reflective side out](https://11145950-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FjxwtZYYk0lvusnMTywNR%2Fuploads%2Fgit-blob-8ce911a1b52f5e6a1b399dca6015bc2fb91b12d3%2Fmarker-reflectivity-vest-applied.jpg?alt=media)

One caveat worth knowing. This material is a stopgap, not a Velogic product, so we cannot warrant it, and nobody has yet tested it properly at the steepest angle of all, a shoulder marker on a mountain bike fit with wide handlebars. It works well in the positions we have tried. If you use it there, we would genuinely like to hear how it goes.

## FAQ

### What does retro-reflective mean?

A normal reflective surface, like a mirror or a shiny piece of metal, bounces light off at an angle. Shine a torch at it from one side and the light goes off to the other side.

A retro-reflective surface sends light **back the way it came**, no matter what angle it arrived from. Road signs, hi-vis vests and cats' eyes all do this. That is why a road sign lights up brilliantly in your headlights when you are the one holding the light source, but looks fairly dull to a pedestrian standing to one side.

The material achieves this with thousands of tiny glass beads or microscopic prisms, which act as tiny corner mirrors.

### Why do Velogic markers need to be retro-reflective?

Velogic Studio's camera has an infrared light source sitting right next to its infrared sensor. It floods the scene with IR light and looks for what comes back.

Because the light source and the sensor are effectively in the same place, a retro-reflective marker sends the light straight back into the sensor and shows up as an intensely bright point, far brighter than skin, clothing or bike parts. That brightness difference is what lets the software pick out seven markers from a cluttered scene reliably, frame after frame, and it is also how we filter out unwanted reflections from rims, logos and shiny frame parts.

An ordinary reflective marker only manages that when it happens to be pointing straight at the camera. On a rider's shoulder, ankle or hip, at the range of angles a pedal stroke goes through, that is not good enough.

### If the dots still look shiny, why don't they work?

Because looking shiny to your eye and returning infrared to a sensor an inch away from the light source are different things. An affected dot still reflects, it just does not reflect *back along the same path*. The camera is standing in the one place the light is not going.

### How can I tell which of my rolls are affected?

Please do not try to sort them by eye. We do have visual tests, but they need controlled lighting and a known-good roll for side-by-side comparison, and in other hands they produce false positives more often than real ones. Use the software instead: apply a marker from a different roll and see whether the red dot is steady. Set aside any roll that fails, keep a count of how many there were, and let us know the number.

### Which batches are affected?

We cannot yet tell you reliably, which is part of the problem. The rolls were not lot-marked, so we cannot map a roll in your hand back to a production run. Broadly, the issue appeared in tape produced from early 2026, it is not present in older green tape, and the most recent production is much improved but not perfect. Future runs will be lot-marked so this question has a real answer.

### Does this affect the accuracy of my fit data?

Not directly. A marker is either detected in a given frame or it is not; when it is detected, its position is as accurate as ever. What you lose is continuity, and the software needs all the markers to build the skeleton, so dropouts cost you capture time and can leave gaps in the analysis.

The one real accuracy risk is indirect: if you move a marker away from its correct anatomical landmark to make it detect (a shoulder marker relocated onto the upper arm, for instance), the numbers change, and that fit is no longer comparable with your others. If you have to do that to get a capture, note it in the fit record.

### Which markers are worst affected, and why?

Shoulder, hip, ankle, toe and heel. All of them sit on curved or sloping surfaces, so the marker sits at an angle to the camera rather than facing it. Knee and elbow markers usually face the camera fairly squarely and tend to be fine. Mountain bike fits are the hardest case overall, because the rider is more upright and wide bars push the hands and shoulders further round.

### Is my camera or my lighting at fault?

If a marker on a good roll detects reliably in the same position where a marker from another roll does not, no. That said, your setup can make a marginal marker much worse, which is why step 2 comes before any of the marker steps: a marker near the edge of the frame, or a camera further than about 8 feet (2.4m) from the plane of the bike, will drop out on its own account. Strong sunlight or IR-rich lighting raises the background too. See [Setting up the fit area](/section-01-getting-started/setting-up-fit-area.md) and [Lighting & environment](/section-01-getting-started/lighting-environment.md).

### Can I use any retro-reflective sticker I find?

Not reliably. Plenty of products sold as "reflective" are not retro-reflective at all, and coloured films are usually much dimmer than silver or white ones. Stick to plain silver or white retro-reflective film from a recognised manufacturer, in roughly 20mm, and always over the top of a Velogic dot rather than on skin. We tested a lot of generic alternatives when the software was being developed, which is why we make our own tape rather than recommending something off the shelf.

### Will you charge me for replacements?

No. We replace affected tape at no cost, whether you bought from us directly or through a distributor.

### Are you replacing my whole order, or only the bad rolls?

We replace the markers that are actually affected rather than swapping out every roll you hold, because most of your stock is very likely fine and a wholesale swap would leave you waiting on freight for tape you do not need. Tell us how much you are getting through and we will make sure you have enough good markers to keep fitting.

### Do I have to send the bad rolls back?

No, and please don't. We have plenty of affected rolls here to test against, so yours are more useful to you than to us. Just keep them to one side rather than throwing them out, in case we need to come back to you, and tell us how many of the box turned out to be bad.

### Who do I contact?

<support@velogicfit.com>, or [fill in the reporting form](https://forms.cloud.microsoft/r/DHig4Lt4Y2). See our [support policy](/general/support-policy.md) for how support works.