2026 Ibis Oso HD vs 2026 Forbidden Heathen Framekit
The S3 is the Forbidden Heathen Framekit size closest to your XM 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 XM, the Forbidden Heathen Framekit in S3 places the top of the head tube 7 mm lower and about as far forward, relative to the bottom bracket. Its wheelbase is 63 mm shorter, which can contribute to quicker direction changes.
- Frame stack
- −7 mm
- Lower front end
- Frame reach
- +1 mm
- About the same reach
- Wheelbase
- −63 mm
- Shorter: quicker to change direction
- Head angle
- +0.9°
- 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 S3 are missing the chainstay length.
Geometry side by side
| Measurement | Ibis Oso HD XM | Forbidden Heathen Framekit S3 | Difference |
|---|---|---|---|
| Reach | 474 | 475 | +1 mm |
| Stack | 646 | 639 | −7 mm |
| Head tube angle | 63.1 | 64 | +0.9° |
| Seat tube angle | 76.6 | 76 | −0.6° |
| Chainstay length | 455 | not listed | |
| Wheelbase | 1295 | 1232.2 | −63 mm |
| BB drop | 21 | not listed | |
| BB height | 352 | 311 | −41 mm |
| Standover | 745 | 740 | −5 mm |
| Seat tube length | 405 | 440 | +35 mm |
| Head tube length | 121 | 110 | −11 mm |
| Effective top tube | not listed | 634 | |
| 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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