The A12 system

The A12 is the SPEEDHUB version for 12 mm thru-axle frames. The gearbox is the same; only the axle differs: instead of the frame’s own thru-axle, two special M7 bolts hold the hub, screwing into both ends of the axle through bushings fitted or threaded into the dropouts, with Nord-Lock locking washers.

Versions

Dropout width	Spoke holes	Colour	Axle plate by brake mount
142/148 mm	32 or 36	silver, red, black	IS: A12 DB OEM2 (SPEEDBONE or MonkeyBone) · PM: A12 DB PM (PM Bone)
177 mm	32	black	IS: A12 DB OEM2 XL · PM: A12 DB PM XL
197 mm	32	black	A12 DB OEM2 XXL (MonkeyBone-10 or Fatbone)

The A12 comes as a disc-brake version only and is not approved for tandems. The PM Bone and Fatbone also act as adapters, so they need a disc one size larger — details: Torque support.

Why an installation check?

Thru-axle dropouts have no common dimensions. The axle system — thread pitch, conical or flat seat, threaded insert — and the thickness of the dropouts vary from frame to frame. So an A12 does not come off the shelf: first we measure the frame, and from the measurements we select — or have made — the bushings and spacers for the left and right dropouts.

The check has two steps:

1. The axle plate lies flat. The sample axle plate and torque support are held to the left dropout in their final position. The plate must lie flat over 40 mm around the axle — if a weld or a reinforcement lifts it even slightly, hub and disc would sit crooked, and the SPEEDHUB cannot be fitted.
2. Measuring the dropouts with test bushings and a caliper, on both sides.

The possible results:

Result	What it means
Compatible — 0.5–1.0 mm gap between bushing and axle plate	the bolt clamps bushing and axle plate firmly to the dropout and engages deep enough
Dropout too thin	the bolt only clamps the bushing, and the hub can move in the dropout; a bolt that goes in too far can also jam the shift shaft
Dropout too thick (gap over 1 mm)	the bolt engages too few threads and can break

Borderline cases can be bridged with spacers or custom bushings — the measurement decides that too. For how the measurement works, choosing the axle plate and support, and fitting the bushings, see Fitting an A12 for the first time.

Powder-coated dropouts

The measurement can be taken on the powder coat. If the coat chips off after the wheel has been removed and refitted several times, one shim per side on the outside of the dropout makes up for it.

Safety rules

• Use only original Rohloff A12 bolts and original Nord-Lock washers. A Nord-Lock washer can be opened at most four times, then it has to be replaced (Art. no. 8574).
• The A12 mounting parts — bushings, cones, spacers, bolts — belong to that frame and that side (L/R marking). Moving the hub to another frame takes a new measurement and new parts.
• After removing the wheel, every bushing and spacer must go back exactly as it was — see Removing and fitting an A12 wheel.
• Do not fit a trailer coupling directly to the axle or the A12 bolt: the bolt would engage too few threads and could tear out.
• For theft protection, a 5 mm PIT-Stopper or Hexlox insert can be used — check the A12 bolts’ torque (15–20 Nm) first.
• Keep the owner’s card: its sticker lists the part numbers of the left and right A12 parts, so they can be reordered at any time.

Conversion and supply

An existing CC or TS SPEEDHUB cannot be converted to A12 in a workshop or at home: only Rohloff does it, as part of a paid factory overhaul. We order the overhaul for you, and first check that your frame takes A12: The check before a conversion.