The old jump design page on Trailism started as a rough calculator I uploaded back in 2014. It worked, but it never grew into what I actually wanted: something that treated trail features as a real physics problem instead of a back-of-the-napkin sketch.
That tool finally exists, and it has its own home now: TrailACT — Trail Assessment and Construction Tools. It’s a separate company and a separate platform, built specifically for physics-based trail feature design.
The first tool in the suite is BASE-Bf — Building, Assessment, and Simulation Explorer for Bike Features. It’s a deterministic physics engine for designing and assessing bike jumps, drops, and rollers. Some of what it does:
- Generates clothoid ramp geometry bound by G-force limits per bike mode (DJ/BMX, trail/enduro, DH)
- Computes Equivalent Fall Height (EFH) across the full landing surface
- Solves three-speed (or four-speed with pop) ballistic trajectories per feature
- Chains up to five features in sequence with automatic speed handoff
- Exports blueprint-scale DXF (named layers) and single-page PDF
- Runs an assessment mode on existing features from measurements or imported profile coordinates
The methodology page on the TrailACT site goes into the modeling philosophy — explicit scope, deterministic outputs, conservative assumptions, and clear separation between physics and visualization. The purpose page lays out what the tool is and isn’t (it’s a planning aid, not an engineering certification).
If you build trails or design bike parks and want to try BASE-Bf, request access here.
The Trailism jump design, roller design, and jump building guide pages aren’t going anywhere — those are still where the conceptual writing lives. TrailACT is where the math runs.