V1.0 // GARWIN, IA
A triple-butted 4130 chromoly frame is a static object until a mass moves upon it. The frame tolerates 320 Nm of preload only because the rider distributes that load correctly. This page defines the human variable.
The chassis is tuned for a rider mass range of 70–95 kg. Outside this band, the headtube angle shifts under braking load, altering trail and stability. The seat tube's triple-butting profile compensates for vertical compression, but lateral torsion depends entirely on rider posture.
| METRIC | TARGET RANGE | TOLERANCE | FAT MODE |
|---|---|---|---|
| Total Mass (Rider + Kit) | 70 – 95 kg | ± 2.5% | > 100 kg: Headtube deflection increases 4° under hard brake.|
| Center of Gravity (Vertical) | 850 – 950 mm (BB) | ± 20 mm | High CG (>950mm): Risk of rear wheel hop on rough terrain.|
| Saddle Setback | -50 to -65 mm | ± 2 mm | Excessive setback: Torque loss on climbs; chainstay whip.
FRAME_GEO_V1These dimensions assume a standard 100mm headset cup height. Deviations require spacer adjustments to maintain the intended stack. A misaligned headset introduces shear stress into the fork crown—a failure mode we do not negotiate.
Per @brian-beaulieu's variance thesis: a properly loaded frame emits a consistent 3.2 dB delta threshold under pedaling load. Listen for the hum. If the frequency drifts, the preload window has shifted. The rider is the sensor.
This profile integrates the thermal mass logic of