Nelson Gaitan
PRODUCT DESIGNER
← All work
Case study 03 · Personal project · In progress

Mo, a running partner that helps you choose your next shoe

There are hundreds of running shoes, but most shopping tools still answer with a long list of results. Runners end up comparing specs, prices and reviews on their own. Mo is an independent AI running partner. A store knows its catalog, but Mo knows the runner.

Try the live prototype ↗
Welcome back! Your Cloudsurfer Max is probably due for a replacement.
Yes, find me something under $200
YOUR PICKS · 1 TOP PICK, 2 ALTERNATES

Each one explains why it fits your rotation, with the price and where it belongs.

Role
Product Designer, design and build
Type
Personal project
Built with
Claude Haiku 4.5, Supabase, GitHub Pages
Status
Live prototype
At a glance

The problem

Runners don't need more search results. They need to know which shoe to buy next, and whether they need one at all.

The shift

An agent, not an advisor. Mo speaks up first, checks the rotation, narrows it down, and points to a store.

The result

A live prototype where the model chooses three picks and explains each one.

01
The challenge

Runners don't need more results, they need a decision

Most runners keep a rotation: one shoe for easy runs, one for speed workouts and one for race day. So the real question isn't only which shoe is good, it's which shoe they need next.

Today that decision falls on the runner. Lots of options, confusing specs and not knowing when to replace a shoe make it easy to buy the wrong thing, or to put off buying anything.

Mo is for the intermediate runner training for a half or full marathon, with two or three shoes in rotation, at the moment they want something new: their usual model changed or sold out, or they're curious about another brand.

02
The approach

The best shoe buying help is a good human in a running shop

Mo is that, without the shop. It isn't owned by a store, so it's on the runner's side. I summed up the positioning as taste plus safety: taste gets the runner to open it, safety is why they trust the pick.

Intake→Rotation check→One clarifying question→Three picks→Refine
03
Key decision 1

Check the rotation before recommending anything

Typical tools

Recommend a good shoe, even if it does the same job as one the runner already owns.

Mo

Starts with the shoes the runner owns, notices a missing shoe type, and says so once. If there's no gap, Mo says that too.

WHY IT MATTEREDA partner that sometimes says "you don't need one yet" is easier to trust when it does recommend something.
04
Key decision 2

Three picks, not a list

Typical tools

Dozens of results, and the runner still has to do the comparing.

Mo

One top pick and two alternates, each with the price, what it's for, and why it fits this runner's rotation.

WHY IT MATTEREDThe runner gets a decision they can act on, not more research to do.
05
Key decision 3

Ask in three taps instead of connecting Strava

The first plan

Connect Strava or Garmin to read mileage automatically.

What shipped

The runner adds their shoes in three taps and a rough mileage once. Mo estimates forward and says "probably" when it guesses.

WHY IT MATTEREDStrava's June 2026 API policy bans using its data in AI applications, and Garmin's developer program is paused for new applicants. Designing around it made Mo simpler and more honest about what it knows.
06
Where it stands

A live prototype with a real model behind the picks

Model-chosen picks

Claude Haiku 4.5 chooses the picks and writes the reason on each card. Scripted picks step in if the call fails.

Remembers the runner

The rotation is saved in the browser. Mo opens with "Welcome back" and names the shoe that's probably due.

Around the run

A race question with a countdown, and a store finder by ZIP code. Mo can't see stock, so it says to call ahead.

Where Mo goes next

Test the recommendations with intermediate runners, add more tempo shoes to the catalog, and let runners add a shoe from a photo. After shoes, Mo can grow into training plans, tips, and gear beyond shoes.