A size-by-size geometry profile with manufacturer provenance and RideDNA consistency-audit context. Use the complete table to compare fit and handling before opening the interactive tools.
Source: Manufacturer geometry source
Provenance: published is present in the manufacturer data; derived is calculated by RideDNA; manual is a staff-entered reference rather than a manufacturer-chart value. “Not published” means the manufacturer did not provide a value for that size.
| Size | Stack | Reach | HTA | STA | ETT | Chainstay | Wheelbase | Front center | BB drop | Trail | Fork offset | Audit context |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 44 | 501 mm published | 366 mm published | 70.5 ° derived | 75.5 ° derived | 496 mm derived | 410 mm derived | 970 mm published | 572 mm published | 74 mm derived | 71.0 mm published | 47 mm published | green |
| All 5 consistency checks passed | ||||||||||||
| 49 | 514 mm published | 375 mm published | 71.8 ° derived | 75.5 ° derived | 509 mm derived | 410 mm derived | 973 mm published | 574 mm published | 74 mm derived | 63.0 mm published | 47 mm published | green |
| All 5 consistency checks passed | ||||||||||||
| 52 | 527 mm published | 380 mm published | 72.5 ° derived | 74.0 ° derived | 531 mm derived | 410 mm derived | 975 mm published | 577 mm published | 74 mm derived | 58.0 mm published | 47 mm published | green |
| All 5 consistency checks passed | ||||||||||||
| 54 | 544 mm published | 384 mm published | 73.0 ° derived | 74.0 ° derived | 541 mm derived | 410 mm derived | 978 mm published | 579 mm published | 72 mm derived | 58.0 mm published | 44 mm published | green |
| All 5 consistency checks passed | ||||||||||||
| 56 | 565 mm published | 395 mm published | 73.5 ° derived | 73.5 ° derived | 563 mm derived | 410 mm derived | 991 mm published | 592 mm published | 72 mm derived | 55.0 mm published | 44 mm published | green |
| All 5 consistency checks passed | ||||||||||||
| 58 | 591 mm published | 402 mm published | 73.5 ° derived | 73.5 ° derived | 577 mm derived | 410 mm derived | 1006 mm published | 606 mm published | 72 mm derived | 55.0 mm published | 44 mm published | green |
| All 5 consistency checks passed | ||||||||||||
| 61 | 612 mm published | 408 mm published | 74.0 ° derived | 73.0 ° derived | 595 mm derived | 410 mm derived | 1013 mm published | 613 mm published | 72 mm derived | 52.0 mm published | 44 mm published | green |
| All 5 consistency checks passed | ||||||||||||
Overall consistency: green. This context is shown alongside the table so a rider can distinguish a complete published specification from a value that RideDNA had to derive or could not independently verify.
The Specialized Tarmac SL8 geometry specification demonstrates strong internal consistency across all seven sizes. All checks — stack, reach, wheelbase, front center, and trail — reconcile within ±1mm engineering tolerance. The RideDNA Geometry Engine reconciliation confirms internal self-consistency, with all back-calculated dimensions aligning within ±1mm (or ±0.2° for angles). One diagnostic note: seat tube angle shows an unusually large step of 1.5° between sizes 49 and 52 (75.5° → 74°), which may warrant verification — the root cause cannot be determined from the published geometry data alone.