Senior Technical Lead (Full-Stack & Applied ML) (Contract)

About Bells of Steel Inc.

At Bells of Steel, our mission is to make fitness and strength training approachable, affordable, and fun. We design and manufacture high-quality strength and exercise equipment for home gym owners and fitness professionals, helping people of all experience levels achieve their goals.

We’re not your typical fitness equipment brand. We’re down-to-earth, a little cheeky, and focused on making fitness more rewarding and less intimidating. If you enjoy a fast-paced, no-BS environment and want to help shape the future of strength training, you’ll fit right in.

Our Core Values: A.C.T.

Adaptability – Raise the Bar
We challenge the status quo, learn quickly, and continuously improve. We embrace change, seek better ways of working, and take initiative to drive results.

Customer Centricity – Always Spot the Customer
Everything we do is focused on helping our customers succeed. We lead with empathy, build trust through action, and create value for both external and internal customers.

Teamwork – We Win Together
We operate with honesty, transparency, trust, and respect. We collaborate openly, take shared ownership of outcomes, and succeed as a team.

About the role

We're looking for someone to own the build and own the evidence.

We're building a training app that makes the gear people already own more useful. Our founder built the working version, and it's in private TestFlight testing now. Alongside it we're running a wearable research program testing whether affordable sensors can give people better coaching.

You'll be the technical owner of both. You'll take a real app to public launch and keep it running, and you'll design the sensor and ML experiments that tell us what actually works. You work directly with the founder. This is hands-on: you write the code, look at the data and make the calls.

The roadmap: public app launch in December 2026, and sensor launch by March 31, 2027.

What's in it for you

• This is a 6-month contract role ending in March 2027, with the potential to transition to full-time based on performance and business needs
• CAD $80,000–$100,000 base salary
• Health Spending Account
• A Calgary office you'll actually want to come into
• Employee discounts on all our gear
• Access to our staff gym
• A team that actually likes what they do

The schedule & location

This is a hybrid role based at our Calgary location, where the core hours are Monday to Friday from 8:00am to 4:30pm

The non-negotiables

You build with Claude Code first, and you check its work after. You can let Claude take the lead and you act as an architect.

You lift. You know sets, reps, RPE, progression and rest periods, and you're at home around barbells, racks, benches, dumbbells and cable machines. No coaching certifications needed. You do need to understand what our customers are doing in their garage.

You're in Calgary. You live here or you'll move here before your start date. The job is hybrid but you are expected to come on-site around 3 times a week to work with our equipment, coaches and product team, so remote from another city or country won't work.

What you'll do

• Take our React Native/Expo and TypeScript app, Supabase/Postgres backend and local-first data through release, monitoring and day-to-day operation
• Build the hard backend and data pieces yourself: reliable sync, access control, sensor ingestion, versioned datasets, model interfaces, and failures we can actually see
• Work with our team of 2 in-house personal trainers, 2 biomechanical engineers and the visionary to design the wearable measurement and ML experiments: reference comparisons, simple baselines, participants and sessions kept separate, uncertainty estimates and honest limits on what we release
• Turn validated findings into coaching features with confidence checks, a manual fallback, and sensible behaviour when the signal is missing or unreliable
• Set technical priorities with the visionary, review AI-assisted code and analysis, and keep decisions and experiment records reproducible

What Success Looks Like

• Within 90 days you own the release process of the app
• The first wearable experiments are running, with reproducible baselines
• The app is on track for its December public launch on Android, iOS and web
• When we make the March wearables call, it rests on evidence, not a demo

What We're Looking For

• You've shipped production mobile apps and supported them after launch
• You've personally built and properly evaluated an applied ML system, and that evaluation drove a real product or deployment decision
• Strong backend, SQL, API and authorization skills, plus practical React/TypeScript. You can own mobile releases and debug state, sync and recovery problems
• Python, statistics and applied ML fundamentals. You can explain leakage, reference error, calibration, and why a model that looks great in a notebook falls apart on new users
• You've owned technical design and made delivery calls on your own. That's usually 6+ years, but depth matters more than the number
• You improve an existing codebase instead of rewriting it, ship small releases you can verify, and explain trade-offs in plain language
• Experience with iOS and Android development
• Experience with BLE data capture

Bonus Points

• React Native/Expo and Supabase
• Wearable or time-series data, signal processing
• Model deployment

You own the app, the data pipeline and the ML calls. We care more about what you've built than where you learned it.

The Interview Process

• 30 minute screening with our HR Coordinator
• 1 hour screening with our hiring team
• Paid, time-bound technical assessment
• 1 hour follow up to discuss technical assessment
• Reference check (include 2-3 in resume)
• Decision made and offer sent out