2026 Ibis Oso HD vs 2026 Forbidden Heathen Framekit
The S1 is the Forbidden Heathen Framekit size closest to your S Ibis Oso HD. We match frame stack and reach. This is a geometry comparison, not a fit recommendation; stem, spacers, handlebars and saddle setup also affect your riding position.
What changes on the Forbidden Heathen Framekit
Compared with the Ibis Oso HD in S, the Forbidden Heathen Framekit in S1 places the top of the head tube 5 mm lower and 7 mm further forward, relative to the bottom bracket. Its wheelbase is 78 mm shorter, which can contribute to quicker direction changes.
- Frame stack
- −5 mm
- Lower front end
- Frame reach
- +7 mm
- Longer frame reach
- Wheelbase
- −78 mm
- Shorter: quicker to change direction
- Head angle
- +1.7°
- Steeper: sharper steering
- Chainstays
- n/a
- One of the bikes has no number for this
The two frames
Only the Ibis Oso HD is drawn. The Forbidden Heathen Framekit numbers we have for size S1 are missing the chainstay length.
Geometry side by side
| Measurement | Ibis Oso HD S | Forbidden Heathen Framekit S1 | Difference |
|---|---|---|---|
| Reach | 428 | 435 | +7 mm |
| Stack | 626 | 621 | −5 mm |
| Head tube angle | 62.3 | 64 | +1.7° |
| Seat tube angle | 76.1 | 76 | −0.1° |
| Chainstay length | 440 | not listed | |
| Wheelbase | 1233 | 1155.4 | −78 mm |
| BB drop | 27 | not listed | |
| BB height | 346 | 301 | −45 mm |
| Standover | 706 | 716 | +10 mm |
| Seat tube length | 381 | 400 | +19 mm |
| Head tube length | 99 | 90 | −9 mm |
| Effective top tube | not listed | 590 | |
| Fork length | not listed | 541 |
Differences are the Forbidden Heathen Framekit minus the Ibis Oso HD. Full charts: 2026 Ibis Oso HD, 2026 Forbidden Heathen Framekit.
Where each sits in its class
Ibis Oso HDForbidden Heathen Framekit
Each bike is ranked against the other trail bikes on Quiver, on frame geometry alone. Not your hand position or ride feel.
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