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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| L | 565 mm published | 395 mm published | 73.5 ° derived | 73.7 ° derived | Not published | 408 mm derived | 987 mm derived | 590 mm published | 72 mm derived | 57.0 mm published | 43 mm published | green |
| All 4 consistency checks passed | ||||||||||||
| M | 540 mm published | 386 mm published | 73.0 ° derived | 74.0 ° derived | Not published | 408 mm derived | 978 mm derived | 581 mm published | 72 mm derived | 57.0 mm published | 45 mm published | green |
| All 4 consistency checks passed | ||||||||||||
| S | 520 mm published | 377 mm published | 71.9 ° derived | 74.5 ° derived | Not published | 408 mm derived | 976 mm derived | 580 mm published | 74 mm derived | 59.0 mm published | 50 mm published | green |
| All 4 consistency checks passed | ||||||||||||
| XL | 590 mm published | 404 mm published | 73.5 ° derived | 73.0 ° derived | Not published | 408 mm derived | 1003 mm derived | 606 mm published | 72 mm derived | 57.0 mm published | 43 mm published | green |
| All 4 consistency checks passed | ||||||||||||
| XS | 495 mm published | 368 mm published | 70.8 ° derived | 75.0 ° derived | Not published | 408 mm derived | 974 mm derived | 578 mm published | 74 mm derived | 61.0 mm published | 55 mm published | green |
| All 4 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 Colnago Y1RS geometry reconciles within ±1mm engineering tolerance across all five sizes for stack, reach, front center, and trail. The manufacturer has withheld effective top tube length (ETT), requiring the engine to derive it from the published reach, stack, and seat tube angle values. This derivation prevents independent verification of reach and wheelbase — the reach check confirms algebraic consistency only, and wheelbase cannot be computed without a published reference value. By withholding effective top tube length, the manufacturer prevents independent scrutiny of its geometry claims and denies consumers the data they need to evaluate handling characteristics or make meaningful comparisons with competing models. This is not an obscure technical figure — it is a standard dimension routinely published by competing manufacturers. This is a deliberate choice, not a technical limitation. Consumers cannot fully assess fit, predict handling, or compare this bicycle on equal terms without it. Transparency about geometry is not optional: it is the minimum standard a manufacturer owes to buyers making thousands-of-dollars purchasing decisions.