u/Signal-Employment610

For a while I was trying to consciously bring my running cadence up from the 150s to around 165–170 SPM to reduce heel striking and shin pain.

I tried using a running metronome app, but listening to a robot click in my ear for 5 miles was soul-draining. So I went back to music, but that’s when I noticed a weird subconscious trap:

Whenever a random 125 BPM track came on shuffle, my stride tempo would naturally drag down with the rhythm without me realizing it. Then a 180 BPM track would come on, and I'd accidentally surge, spiking my heart rate.

The breakthrough for me was realizing two things:

1.Tight BPM windows (±3–5 BPM): Having music matched to my exact target cadence made holding my stride turnover completely effortless—like running on autopilot without staring at my watch.

2. The "Halftime" trick (85 BPM = 170 SPM): I used to think I only had to listen to frantic, hyper-fast songs to hit 170 SPM. But an 85 BPM track hits the beat on every two steps (locking right into your lead foot). It opened up so much hip-hop, indie, and pop that still kept my turnover right on target without feeling rushed.

Pre-made "170 BPM running playlists" on streaming platforms are usually full of generic EDM remixes or songs with completely wrong BPM tags. Curious how many of you intentionally match song tempo to your running cadence? Do you find full-time tracks or half-time beats easier to lock into?

### ⚠️ Mandatory Requirements

Before clicking the link, please ensure you meet these two prerequisites:

* 📱 **Device:** Must be using an iPhone (iPad support is disabled).

* 🎵 **Music Account:** Requires an active Apple Music subscription (the app utilizes Apple's native MusicKit framework to read and filter your catalog).

---

### 🏃‍♂️ What is RunSync?

I am a solo engineer building a utility designed to clear out the friction of finding the right running music. Instead of hunting for pre-made pacing playlists, **RunSync** lets you set a specific, static target cadence (e.g., 175 or 180 BPM).

The app then looks at your music and automatically filters your audio catalog to serve up tracks that perfectly match your exact target target performance rhythm.

### 🧪 What I Am Testing

I am looking for 20–50 runners to try an early-stage build on their physical iPhones. Because this build relies on manual cadence entry to sort your audio, the core focus of this test flight is checking:

1. Core MusicKit API loading and playlist filtering speeds.

2. Background audio playback stability while you run.

3. Proper entitlement mapping through the paywall engine.

### 🎁 The Tester Bounty

Because this is running through the Apple Sandbox ecosystem, **all premium/Pro in-app subscriptions are 100% free** while testing.

If you use the app on a workout and submit a quick line of feedback or a bug report via the TestFlight portal, **I will permanently hardcode your User ID for a lifetime free Pro entitlement** once the application goes live on the App Store.