Inertia Indicator Explained

Donald Dorsey's Inertia takes his Relative Volatility Index and smooths it with linear regression. The name is the thesis: a trend is 'mass in motion', and inertia above 50 means the motion is still bullish regardless of daily noise.

How It Works

• The RVI (volatility measured directionally) is computed first.
• A linear-regression smoothing extracts its underlying direction.
• Above 50 = positive inertia (bullish); below 50 = negative.

How to Trade It

Inertia is a regime flag, not a trigger: hold a long bias while it sits above 50 and let faster tools time entries. Crossings of 50 that hold for several bars mark genuine regime changes worth repositioning around.

Building It in Setup.Cash

Add Inertia in the strategy builder — the length input controls its sensitivity — and use its value in any entry, exit, or filter condition. You can also combine it with other tools in the Indicators Lab or via the AI indicator generator. See the underlying RVI for the raw signal. For the full category overview, see the advanced momentum library guide.

Momentum signals are timing tools — combine them with a trend or regime filter and backtest the exact rules before going live.