Torque support

Every hub gear’s axle wants to turn as you ride: backwards in the reduction gears, forwards in the overdrive gears. That reaction torque has to be taken up by the frame. A three-speed hub makes do with a flatted axle in the dropouts, but the SPEEDHUB’s wide gear range calls for far sturdier support.

How big is the torque?

The reaction torque as a percentage of the torque on the cranks:

Gear	1	2	3	4	5	6	7	8	9	10	11	12	13	14
%	98	82	68	55	44	34	25	18	11	5	0	5	9	12
Direction	back	back	back	back	back	back	back	back	back	back	—	fwd	fwd	fwd

Example: pressing the pedal with 20 kg is about 34 Nm at the crank. In gear 8, 6 Nm of that reaches the support; in gear 1, 33 Nm.

The four solutions

In each, two points stop the axle turning: point A is always the axle stub in the left dropout, point B depends on the solution.

Solution	Point B	For which frame
Long torque arm	the arm’s end, clamped or quick-released under the chainstay	almost any — the arm has to be released to remove the wheel
OEM axle plate	the support block in the extended slot of a Rohloff OEM dropout	Rohloff OEM dropouts only — slides out by itself on removal
OEM2 axle plate	the plate’s fork hooks round a pin or a bolt head	frames with an IS disc mount
PM axle plate	the plate’s fork hooks round the PM Bone’s pin	frames with a direct Post Mount brake mount

Which suits which frame: Which frame does it fit?. Fitting the long arm is covered in Fitting the long torque arm.

The OEM2 options

The OEM2 plate’s fork has to hook into something. There are four ways:

• Support bolt through the disc mount — if there is an IS mount but no disc brake. An M6×16 bolt with washer and self-locking nut, from the inside through the rear brake tab (8 Nm).
• Support bolt through the rack eyelet — if the dropout has an M6 or M5 threaded hole 39.9 mm from the axle centre. An M5 hole needs the OEM2 adapter (Art. no. 8552), because an M5 bolt head is only 8 mm across.
• SPEEDBONE (Art. no. 8550) — for an IS caliper. It goes on the brake tabs from the outside and is bolted together with the caliper, using the SPEEDBONE’s longer bolts instead of the caliper’s own.
• MonkeyBone — for a Post Mount caliper on an IS frame. It goes on the brake tabs from the inside: Art. no. 8553 for a 160 mm disc, 8554 for 180 mm; for fat bikes (190/197 mm) the -10 versions. A 200 mm disc needs the 180 MonkeyBone plus a PM+20 adapter, a 203 mm disc a PM+23.

Where the support point sits

With a CC or TS axle, the support point must be behind the imaginary line through the axle slot. In front of it, the high torque of the low gears can twist the axle out of the dropout — risk of accident. With an A12 axle this cannot happen.

Caution

The M5 adapter with an M5 bolt is not approved for tandems or for e-bikes above 250 W rated / 800 W peak power. OEM2 mounting is only allowed with the frame maker’s approval.

PM Bone and Fatbone

The PM Bone (Art. no. 8555) uses a direct Post Mount brake mount as the support, with a PM axle plate (CC PM: 8225, A12 PM: 8558), for 135–177 mm frames. It also acts as an adapter, so you need a disc one size larger:

Frame	Disc
PM 140	not possible
PM 160	180 mm
PM 180	203 mm
PM 203	not possible
IS 160 + IS/PM adapter 160	180 mm
IS 180 + IS/PM adapter 180	203 mm

The axle plate must lie flat over 40 mm around the axle and must not touch any other part of the frame. The gap between the PM Bone’s pin and the plate must be at least 0.3 mm on a 160 frame and at most 7 mm on a 180 frame.

The Fatbone (Art. no. 8556 for a 180 disc, 8557 for 203) does the same on 190 and 197 mm fat-bike frames, with an OEM2 plate (CC-OEM2-190 or A12-OEM2-197).

Not for tandems

The PM Bone, the PM axle plate, the Fatbone and the 190/197 mm OEM2 plate have not been tested on tandems and must not be used there.