sport / default rider 183 cm
Aprilia RS4 125 vs BMW HP4 ergonomics
Aprilia RS4 125 and BMW HP4 have modeled posture scores within three points for the 183 cm default rider. Treat this as a planning estimate; posture preference, data confidence, and a real test sit still matter.
Modeled fit comparison
Aprilia RS4 125
All contacts reached
BMW HP4
All contacts reached
The modeled scores are within three points, so the result does not distinguish a higher-scoring bike. Treat the result as a planning estimate and compare each bike's geometry confidence before a real test sit.
Rider fit: reaching the ground
The Aprilia RS4 125 lists a 820 mm seat; the BMW HP4 lists 820 mm, within a few millimetres of each other. Seat height is only a first-pass ground-reach input. It does not establish safety or actual foot contact. Seat width, suspension sag, boots, mobility, load, and individual proportions can materially change the result.
Geometry snapshot
| Spec | Aprilia RS4 125 | BMW HP4 |
|---|---|---|
| Seat height | 820 mm | 820 mm |
| Wheelbase | 1,353 mm | 1,423 mm |
| Wet weight | 144 kg | - |
| Displacement | 124 cc | 999 cc |
Posture metrics
Knee angle
- Aprilia RS4 125
- Sport (60.7 deg)
- BMW HP4
- Sport (60.7 deg)
Hip angle
- Aprilia RS4 125
- Neutral (99.6 deg)
- BMW HP4
- Neutral (99.6 deg)
Elbow angle
- Aprilia RS4 125
- Relaxed (143.3 deg)
- BMW HP4
- Relaxed (143.3 deg)
Torso lean
- Aprilia RS4 125
- Forward (25.2 deg)
- BMW HP4
- Forward (25.5 deg)