Tool 03
Frame Geometry Comparator
CategoryGeometry
SetupSpecialized Tarmac SL8 — 56 vs Specialized Roubaix SL8 — 56
| Measurement | A | B | Δ | Unit |
|---|---|---|---|---|
| Stack | 572.0 | 610.0 | 38.0 | mm |
| Reach | 395.0 | 386.0 | 9.0 | mm |
| Head tube angle | 73.50 | 72.75 | 0.75 | ° |
| Seat tube angle (eff.) | 73.50 | 73.50 | 0 | ° |
| Top tube (eff.) | 562.0 | 568.0 | 6.0 | mm |
| Chainstay | 410.0 | 415.0 | 5.0 | mm |
| BB drop | 70.0 | 75.0 | 5.0 | mm |
| Fork rake | 44.0 | 47.0 | 3.0 | mm |
| Head tube length | 180.0 | 220.0 | 40.0 | mm |
| Seat tube length | 510.0 | 510.0 | 0 | mm |
| Wheelbase * | 1,035.0 | 1,056.1 | 21.0 | mm |
| BB height * | 269.0 | 268.0 | 1.0 | mm |
| Trail * | 54.5 | 57.3 | 2.8 | mm |
| Front center * | 631.1 | 647.9 | 16.9 | mm |
| Standover * | 841.0 | 878.0 | 37.0 | mm |
Notes — methodology
- §1
Published vs. derived
Stack, reach, angles, and tube lengths come straight from the manufacturer's geometry chart (each frame links its source chart). Starred rows are computed from them when the chart doesn't publish a value. - §2
Significance thresholds
A delta is set in red when it crosses a rider-feelable rule of thumb — 5 mm of reach, 10 mm of stack, 0.5° of head angle, 3 mm of trail. Below that, fit parts absorb the difference.Source: docs/methodology/geometry-comparator.md - §3
Derived values
Wheelbase, trail, BB height, front center, and standover are computed from the published measurements with the frame's stated wheel size and tire width. Trail uses the standard steering-axis construction.Source: Bicycling Science, Wilson & Schmidt - §4
The drawing
Both frames are drawn from the same measurements the table lists, on a common ground line, wheels at stated size. Frame A in ink, frame B in blue — what you see displaced is the actual displacement.