Hub Motor Measurements

Date: 2026-02-28 Measured by: Tee (digital caliper) Motor: 8" / 10x2.125 hoverboard hub motor (brushless, FOC ESC)

Axle Profile (Stepped / D-Cut Shaft)

The axle has a stepped profile — wider base near the hub, narrower D-cut shaft above.

        ┌─────────┐
        │   3mm   │ ← tip / shoulder
        ├─────────┤
        │         │
        │ ø15.95  │ ← D-cut shaft diameter
        │  (D-cut │   (flat on one side, 13mm across flat)
        │  13mm   │
        │  flat)  │
        │         │
        │ 43.35mm │ ← D-cut section length
        │         │
        ├─────────┤
        │  ø16mm  │ ← base section (measured 16.11mm)
        │  15mm   │ ← base section length
        └─────────┘
        ─── hub face ───

        Total protrusion: 65.5mm

Measurements

#	Dimension	Value	Notes
1	Axle base diameter	16.11 mm	Round section near hub face
2	D-cut shaft diameter	15.95 mm	Round diameter before D-cut
3	D-cut flat width	13 mm	Across the flat
4	Total axle protrusion	65.5 mm	Hub face to tip
5	D-cut section length	43.35 mm	Upper shaft
6	Base section length	15 mm	Lower stepped portion
7	Tip/shoulder	3 mm	Feature at top of shaft
8	Bearing seat OD	~37.8 mm	Hub center collar

Tire Specs

Inflate to 35 PSI (240 kPa / 2.5 BAR)
Size: 10x2.125 pneumatic

Design Implications

Dropout clamp must accommodate stepped profile: 16mm bore at base, D-cut slot above
Anti-rotation via D-cut flat (13mm across flat on a 15.95mm shaft)
Axle length (65.5mm) gives room for dropout plate + nut + washer
Bearing seat (37.8mm OD) — allow clearance on inner face of mount