BetaSamplingScheduler_motorway_edition

If you've generated anything with Flux, you've met the "beta" scheduler whether you realized it or not - it's the schedule the default Flux workflows reach for instead of Karras. BetaSamplingScheduler is the core node that gives you direct control over that schedule's shape through two parameters, alpha and beta. This _motorway_edition is the version wired for agilly1989's Motorway pipe: the model comes out of the Motorway by key, the sigmas go back in by key, and the only wire is the single MOTORWAY 🚌💨.

How it works

The beta schedule is a two-shape-parameter noise schedule - alpha and beta control how the denoising effort is distributed across the steps, and the defaults of 0.6/0.6 are the settings most people never touch. The inputs that matter:

• INPUT_model_key - key for the model (default model). The schedule needs the model to know which architecture it's shaping sigmas for.
• steps - default 20.
• alpha - default 0.6 (range 0–50).
• beta - default 0.6 (range 0–50).
• OUTPUT_SIGMAS_key - where the sigmas land, default SIGMAS.

The wrapper reads the model from the Motorway, calls the real core BetaSamplingScheduler, stores the resulting sigmas under your output key, and returns the Motorway. Nothing else comes out of the node.

Why you'd pick this over BasicScheduler

BasicScheduler gives you the same beta name in its dropdown, but the fixed version with no knobs. This node exists so you can reshape the curve: lower alpha/beta puts more of the denoising work in a particular stretch of the trajectory. In practice, the defaults are a known-good starting point for flow-matching models and most people leave them alone - this is a "I understand the math and want it slightly different" node, not a first stop. If your model is SD1.5 or SDXL, you don't want this at all; you want karras via BasicScheduler. If it's Flux or another flow-matching architecture, beta (fixed or this tweakable version) is the community-endorsed direction, with the caveat from the sampler-sweep threads that the specific alpha/beta values you pick matter less than avoiding Karras entirely.

Motorway specifics

MOTORWAY 🚌💨 is required here, so your chain starts at a MotorwayStart or primitive starter. Whatever key you set for OUTPUT_SIGMAS_key is what the downstream sampler must read - change one and forget the other and you'll hit the pack's signature error, 'MotorwayClass' object has no attribute 'hash_', which just means the key you asked for was never written. Keys also overwrite in this system, so don't reuse SIGMAS for two different schedules in the same chain.

Install

cd ComfyUI/custom_nodes
git clone https://github.com/agilly1989/ComfyUI_agilly1989_motorway

Restart, or find "ComfyUI_agilly1989_motorway" in ComfyUI Manager. No pip dependencies, no model downloads.

Fine print

The pack is an explicitly-beta side project - the README opens with "BIG BROKEN WITH ASYNC WILL FIX WHEN I GET THE TIME/MOTIVATION" - and the current hotfix release has the _motorway_edition clone generation commented out of __init__.py, so on the newest main these nodes may not load at all. An old workflow that references them and reports a missing node is probably hitting exactly that. The author is reachable via GitHub issues; his Discord DMs are, by his own words, a place to be ignored.