ODKI-VBT is a velocity-based training (VBT) sensor made by ODKI, founded by Lodovico Cortelazzo and based in Italy and the Netherlands. It clips magnetically to a barbell and streams bar velocity, displacement and reps to a phone app; its firmware, hardware files and Bluetooth protocol are public.
Product
ODKI-VBT, a velocity-based training sensor for barbell exercises
Vertical axis only: velocity, acceleration, displacement per rep, reps
Battery
400 mAh LiPo, USB-C. Battery life not measured yet
Mounting
3 neodymium magnets in the shell: steel bars only
Accuracy
Not yet validated: no accuracy figure published
How to get it
Three ways, three different statuses.
Build it
Free files, you buy the parts. About €26 in parts with the board bought from DigiKey Italy (October 2026); roughly €20–60 depending on where you buy the Seeed XIAO board. Needs a 3D printer and a soldering iron. Available now: build guide.
Case
Founders case, €19, case only, sensor not included. A paid order: orders open early Novemberorders are open, until 30 November 2026 or until sold out, max 3 per order. Case details · terms of sale.
Ready-made
Sensor + case, €129: a free pre-order, not a purchase. No payment is taken and the sensor is not yet for sale; pre-orders hear from us before any payment is asked. First assembled units ship once CE conformity is in place. Pre-order form.
What it is not
Limits, stated plainly.
Validated
Not yet. ODKI-VBT is being compared with a linear encoder; the method is public and the raw data will be published whatever it shows. Validation status.
Medical
Not a medical device. It is a training and sports-performance tool, not intended for diagnosis, treatment, rehabilitation or injury prevention.
Bars
Steel bars only. It holds with magnets; on aluminium or other non-steel bars it won't hold.
Open source
Source-available, not OSI open source. The hardware and the tracking engine are licensed for non-commercial use only.
Battery life
Not measured yet. It will be published before any sensor is sold.
Licences
What you may do with it.
Full text: LICENSE-HARDWARE and LICENSE-FIRMWARE in the repo. In plain words: licensing FAQ.
Tracking engine
PolyForm Noncommercial 1.0.0
Rest of firmware and tools
Apache-2.0
Hardware
CC BY-NC-SA 4.0
Bluetooth protocol
CC0
Photos
Real photos, no renders.
Photos by Lodovico Cortelazzo (ODKI). Tap to enlarge.
Sensor, front and USB-C portSensor, side with power switchSensor in the Founders caseBuild: board, battery, switchBuild: electronics in the shellBuild: battery seated in the shell