Help and questions

StumpSage is in a closed beta for adults (18+) with an invite. Anyone can open the demo analysis without one: a nets clip filmed from behind. It shows the key moments, but no measurements: knee, trunk and stride numbers need a side-on clip.

Open the demo analysis (filmed from behind)

StumpSage sends you a join link on WhatsApp. It ends in an 8-character code (like ABCD-EFGH) made out to your mobile number. To join, you give that number and confirm you are 18 or older.

Each invite works once. A new invite for the same number brings back your analyses. An invite expires after 7 days unless StumpSage sets it otherwise, and it locks after 5 tries with a different number.

Your date of birth, to check you are 18 or older and for your age group; your batting hand; and your bowling arm, so StumpSage reads your action the right way round. Your name and mobile number come from your invite. When you upload, you can add your height: some measurements need it.

Your analyses stay saved. Invites work once, so ask StumpSage for a new invite for the same number and join with it: your analyses come back with it.

The beta runs on one StumpSage server, so now and then it is down for a while, for example for an update. Your account and analyses are kept. Try again a little later, and if it still won’t load, ask StumpSage for the current link.

One delivery, from before the run-up starts to after the follow-through, with one bowler in frame. Stand level with the bowling crease, on the side of the bowling arm, so the run-up crosses the frame.

The full filming guide

It helps a lot. Normal-speed video still gives the key moments and approximate angles at single moments (front knee at landing, trunk at release), marked “approx.”. Timings, the knee’s change after landing and speeds need 60 or 120 fps; 240 fps is best.

Clips sent through WhatsApp or Instagram lose their slow motion. Upload the original file from your phone.

Side-on gives the most numbers: knee, trunk, stride and release. From behind, StumpSage follows the action and finds the key moments, and can read hip drop at landing and head movement. Rotation and side bend need two phones at once (Lab mode), which isn’t in the beta yet. What each view measures

A phone that films in slo-mo and a way to keep it still at hip height: a tripod, or a kit bag. A steady phone at about 1 m keeps angles true. Lean it on a kit bag if you have no tripod.

MP4 and MOV clips. Convert other formats first. Use the original file from the phone that filmed it: an export or a forwarded copy can lose the slow motion.

Up to 45 seconds: trim it to one delivery, run-up to follow-through. Files can be up to 500 MB.

Big slo-mo files go up in small parts, so a weak connection only resends the part it was on, and the upload carries on by itself when you’re back online. Keep the tab open until it’s done; after a reload, choose the same file and it picks up where it stopped. There is also a daily upload limit in the beta.

Upload the original slo-mo clip. If you move it to a Mac first, AirDrop keeps the original 240 fps (or 120 fps) file, but exporting it from Photos bakes the slow motion into a 30 fps file, and StumpSage can then only estimate the real speed, or not at all.

Your clip with the tracked skeleton, the phases of the delivery (run-up, gather, back-foot contact, front-foot contact, follow-through), the key moments, and every measurement the clip supports, each with how it was measured and how sure StumpSage is. Then the full report.

Usually a few minutes. The server analyses one clip at a time, so yours may wait in a queue first.

Not at first. Measurements reach you as soon as the server has checked them, marked “Not checked by a coach yet”. A StumpSage coach can review an analysis later; when one approves it, it says who checked it.

≈ marks an approximate value, always shown as a whole number. The confidence label (high, medium or low) says how clearly the joints and the moment were seen. Below a floor, StumpSage shows no number: “Not clear enough in this clip to give a number.”

Because the clip can’t support them, and StumpSage won’t guess. The report lists each one under what would unlock it: film side-on, film in slo-mo, add your height, or Lab mode (two phones, not in the beta yet).

Ball speed needs ball tracking, and foot direction needs heel and toe tracking; neither is in the analysis yet.

The server checks every clip before it measures anything. When the checks find a problem (too dark, the bowler too small, part of the body out of frame, no delivery found), StumpSage says which, and how to film it next time.

One card per measurement: your frame at its moment with what was measured drawn on it, a figure of the ideal position (or how it’s measured), what it is, why it matters, what usually happens if it’s off, and the range, with whether it comes from research or a coaching guide. Then what wasn’t measured and what to film next. A clip with no numbers leads with what StumpSage saw.

Yes: the PDF has the same cards. Body Load cards go in only if you switch them on, each time you export. Body Load covers workload, growth and history: share it only with people who look after your bowling.

A separate part of the report for injury-risk indicators: guidance, not a diagnosis. In an analysis, those measurements (side bend, shoulder counter-rotation, hip–shoulder separation, hip turn, the back hip at back-foot contact) are kept apart from the performance cards. In the app, the Body Load check also weighs your bowling log against published workload limits.

If anything hurts while bowling, stop and see a physiotherapist or sports doctor before you bowl again.

No. It never appears in a shared reel, and it goes into a PDF only when you switch it on for that export. It stays with its explanation and the route to a physio.

To StumpSage’s own server, where they are stored and analysed. They leave it only to come back to you, and to the StumpSage coach who checks your analysis, through links that expire after 15 minutes. No analytics, no ads, and no other companies beyond Cloudflare, which carries the connection. Privacy and your clips

Delete any analysis (with its clip and every file made from it) from My analyses, or your whole account from your account page, or reply to the WhatsApp message your invite came in and StumpSage deletes it for you. Backups are kept for 7 days, so deleted data leaves them within a week.

Either. StumpSage Beta is an Android app; the website works in any modern browser, so on an iPhone or a computer, use the website. Both use the same account and the same server, so your analyses show in both.

Reply to the WhatsApp message your invite came in.