Torque Specifications and Concepts

1

Introduction to Torque

Threaded fasteners, such as nuts and bolts, are used to hold many components to the bike. As a fastener is tightened, the fastener actually flexes and stretches, much like a rubber band. This stretching is not permanent, but it gives the joint force to hold together, called “preload,” or tension. Each fastener is designed for a certain range of tension. Too much tightening will deform the threads or the parts. Too little preload will mean the fastener will loosen with use. This can damage components, such as a crank ridden with a loose mounting bolt. Loose bolts and nuts are also generally the source of various creaking on the bike.

Tension in the fastener depends largely upon the amount of torque, the tightening, and the size of the thread. Generally, engineers will specify a thread size large enough to handle the anticipated stresses. For example, the M5 bolt of a water bottle cage bolt would not be a good choice for holding a crank. Even if the bolt were as tight as possible, it would not provide enough force to hold the arm secure to the spindle. The crank-to-spindle interface receives quite a lot of stress, making larger threads (M8, M12, M14) a better choice. The amount of pressure applied by a thread can be substantial in order to hold the joint secure. For example, a fully tightened crank bolt can provide over 14,000 Newton force (3,000 pounds force) as it holds the arm in place.

It is commonly believed that bolts and nuts often come loose “on their own”, for no apparent reason. However, the common cause for threaded fasteners loosening is simply lack of tension during initial assembly. Vibration, stress, use, or abuse cannot typically overcome the amount of clamping force in a properly sized and secured threaded fastener. As a simple rule of thumb, any fastener should be tightened as tight as possible without failure of the thread or the component parts. This means the weakest part of the joint determines the limits of tension, and hence, torque.

2

Torque Measurements

Torque for mechanics is simply a twisting or turning motion around the axis of the thread. This resistance can be correlated to, but is not a direct measurement of, fastener tension. Generally, the higher the rotational resistance, the greater tension in the threaded fastener. In other words, the more effort it takes to tighten a bolt, the tighter it is.

Torque is measured as a unit of force acting on a rotating lever of some set length. In the bike industry and elsewhere, the common unit used to measure torque is the Newton meter (abbreviated Nm). One Newton meter is a force of one Newton on a one meter long lever. Another unit sometimes seen is the Kilogram-centimeter (abbreviated kgf-cm), which is a kilogram of force acting on a lever one centimeter long. It is possible to convert between the various systems.

Also sometimes used in the United States is the inch-pound (abbreviated in-lb.).This is a force of one pound acting at the end of a lever (wrench) that is one inch long. Another torque unit used in the USA is the foot-pound (abbreviated ft-lb.), which is the force in pounds along a one-foot long lever. It is possible to convert between the two units by multiplying or dividing by twelve. Because it can become confusing, it is best to stick to one designation. The units given on the torque table here will be in inch-pounds.

It is possible to convert between the various systems:

• Nm = in-lb x 0.113
• Nm = ft-lb x 1.356
• Nm = kg-cm x 0.0981

3

Torque Wrench Types

Torque wrenches are simply tools for measuring resistance to rotation. There is a correlation between the tension in the bolt and the effort it takes to turn it. Any tool, even a torque wrench, should be used with common sense. A cross-threaded bolt will not properly tighten even with a torque wrench. The mechanic must be aware of the purpose of torque, and what torque and fastener preload are doing to the component joint. It is also important to consider thread preparation, which is discussed in detail in this article.

Beam Type

Park Tool offers two styles of beam type torque wrenches. Both wrenches use 3/8″ square drive to accept standard 3/8″ bits.

The TW-1.2 has a range of 0–14 Nm (0–140 inch-pounds). The TW-2.2 has a range of 0–60 Nm (0–50 foot-pounds).

The beam design is relatively simple, and is accurate for both left-hand and right-hand threading. The socket head holds two steel beams, a primary beam and an indicator or pointer beam. The primary beam deflects as the handle is pulled. The separate pointer beam remains un-deflected, and the primary beam below flexes and moves with the handle. The reading is taken at the end of the pointer, at the reading plate on the primary beam. The handle is moved until the desired reading is attained. These wrenches rarely require re-calibration. If the pointer needle is not pointing to zero when the tool is at rest, it is simply bent back until it does align. Fatigue in the steel is not an issue.

Click Type

Park Tool offers two styles of “click” style torque wrenches. Both wrenches use 3/8″ square drive to accept standard 3/8″ bits.

The TW-5.2 has a range of 2–14 Nm (18–124 inch-pounds). The TW-6.2 has a range of 10–60 Nm (88–530 inch-pounds).

The term “click type” can be misleading. This design of torque wrenches uses a swiveling head. There is a spring that is compressed by turning the handle. At higher settings the spring is compressed more which will allow the head to swivel only at higher resistance of higher torque. At high setting there is an audible “click” noise. But at lower setting there may be little or no noise as the head moves over as it swivels. The head swiveling indicates the resistance or torque has been reached, not the “click” noise.

Torque Limiter

A torque limiter uses a built-in clutch system designed to release when the resistance at the fastener exceeds the resistance of the clutch. Generally, torque limiters are used on lower-torque fasteners such as stems, bars, rotor bolts, cable pinch bolts, etc.

Park Tool offers the ATD-1.2 Adjustable Torque Driver, which covers a range of 4Nm to 6 Nm. To use the ATD-1.2, set the dial to the desired torque, turning the dial either direction. Engage the fastener and turn clockwise. When the tool clicks, the torque has been reached. There is no need to continue clicking — in fact, repeated clicking will wear the clutch mechanism.

4

Bicycle Torque Specifications

Below is a table of torque equivalents and formulas for conversions follow the torque table. The table is also available as a PDF file.

All figures in the table below are in Newton meters and inch-pounds. Note that some companies do not specify torque for certain components or parts. Contact the manufacturer for the most up to date specifications.

Wheel, Hub, Rear Cog Area

Component	Type/Brand	Newton Meters	Inch-Pounds
Spoke tension	Torque is typically not used in wheels. Spoke tension is measured by deflection. Contact rim manufacturer for specific tension recommendations. See TM-1.
Axle	Quick-release: closed cam type	Measured torque not typically used. Common industry practice is resistance at lever half way through swing from open to fully closed. For more see Tire and Tube Removal and Installation.
	Solid axle nuts (non-quick-release type wheels)	29.4–44	266–390
Cassette sprocket lockring	Shimano®	29.4–49	260–434
	SRAM®	40	354
	Campagnolo®	50	442
Hub cone locking nut	Bontrager®	17	150
	Chris King®	12.2	100
	Shimano®	9.8–24.5	87–217
Freehub body	Bontrager®	45	400
	Shimano®	35–50	305–434
	Shimano® XTR w/ 14mm Hex	45–50	392–434

Headset, Handlebar, Seat and Seat Post Area

Component	Type/Brand	Newton Meters	Inch-Pounds
Threaded headset locknut	Chris King® Gripnut type	14.6–17	130–150
	Tange-Seiki®	24.5	217
Stem binder bolt: Quill type for threaded headsets	Shimano®	19.6–29.4	174–260
	Generic brand range	16-18	144–168
Threadless stem steering column binder bolts	Deda®	8	71
	FSA® carbon	8.8	78
	Syncros® cotter bolt type	10.1	90
	Thomson®	5.4	48
	Time® Monolink	5	48
	Race Face®	6.2	55
Stem handlebar binder: 1 or 2 binder bolts	Shimano®	19.6–29.4	174–260
	Control Tech®	13.6–16.3	120–144
Stem handlebar binder: 4-bolt faceplate	Control Tech®	13.6–16.3	120–144
	Deda® magnesium	8	71
	FSA® OS-115 carbon	8.8	78
	Race Face®	6.2	55
	Thomson®	5.4	48
	Time® Monolink	6	53
MTB handlebar end extensions	Cane Creek®	7.9	70
	Control Tech®	16.3	144
Seat rail binder	Shimano®	20–30	174–260
	Campagnolo®	22	194
	Control Tech® two-bolt type	16.3	144
	Control Tech® one-bolt type	33.9	300
	Syncros®	5 each bolt	44.2 each bolt
	Time® Monolink	5	44.2
	Truvativ®	M8 bolt: 22–24 M6 bolt: 6–7.1	M8 bolt: 195–212 M6 bolt: 53–63
Seat post binder*	Campagnolo®	4–6.8	36–60

*NOTE: Seat posts require only minimal tightening to not slip downward. Avoid over tightening.

Crankset, Bottom Bracket and Pedal Area

Component	Type/Brand	Newton Meters	Inch-Pounds
Pedal into crank	Shimano®	35 minimum	309.7 minimum
	Campagnolo®	40	354
	Ritchey®	34.7	307
	Truvativ®	31.2–33.9	276–300
Compression slotted crank pinch bolts	Shimano® Hollowtech® II	9.9–14.9	88–132
	FSA® MegaExo™	9.8–11.3	87–100
Crank adjusting cap	Shimano® Hollowtech® II	0.5–0.7	4–6
	FSA® MegaExo™	0.5–0.7	4–6
Crank bolt (including spline-type cranks and square-spindle cranks)	Shimano®	34–44	305–391
	Shimano® Octalink® XTR® (M15 thread)	40.3–49	357–435
	Campagnolo®	32–38	282–336
	Campagnolo® Ultra-Torque®	42	371
	FSA® M8 bolt	34–39	304–347
	FSA® M14 steel	49–59	434–521
	Race Face®	54	480
	Syncros®	27	240
	Truvativ ® ISIS Drive	43–47	384–420
	Truvativ® square spindle	38–42	336–372
	White Industries™	27–34	240–300
Crank bolt one-key release cap	Shimano®	5–6.8	44–60
	Truvativ®	12–14	107–124
Chainring cassette to crankarm (lockring)	Shimano®	50–70	443–620
Chainring bolt: steel	Shimano®	7.9–10.7	70–95
	Campagnolo®	8	71
	Race Face®	11.3	100
	Truvativ®	12.1–14	107–124
Chainring bolt: aluminum	Shimano®	5–10	44–88.5
	Campagnolo®	8	70.8
	Truvativ®	8–9	70.8–79.6
Bottom bracket: cartridge type	Shimano®	49.1–68.7	435–608
	Shimano® Hollowtech® II	34.5–49.1	305–435
	Campagnolo® (three-piece type)	70	612
	Campagnolo® Ultra-Torque® cups	35	310
	FSA®	39.2–49	347–434
	Race Face®	47.5	420
	Truvativ®	33.9–40.7	300–360
	White Industries™	27	240

Derailleur and Shift Lever Area

Component	Type/Brand	Newton Meters	Inch-Pounds
Drop bar dual control brake/shift lever clamp bolt	Shimano® STI™	6–8	53–70
	Campagnolo®	10	89
	SRAM®	6–8	53–70
Shift lever: upright/flat bar type	Shimano® STI™	5–7.4	44–69
Shift lever: twist grip	Shimano® Revoshift®	6–8	53–70
	SRAM®	17	150
Shift lever: MTB “thumb type”	Shimano® STI™	2.4–3	22–26
Front derailleur clamp mount	Campagnolo®	5	44
	Campagnolo®	7	62
	Shimano®	5–7	44–62
	SRAM®	4.5	39.8
	SRAM®	5–7	44–62
Front derailleur cable pinch bolt	Shimano®	5-6.8	44–60
	Campagnolo®	5	44
	Mavic®	5–7	44–62
	SRAM®	4.5	40
Rear derailleur mounting bolt	Shimano®	8–10	70–86
	SRAM®	8–10	70–86
	Campagnolo®	15	133
Rear derailleur cable pinch bolt	Shimano®	5–7	44–60
	SRAM®	4–5	35.4–44.2
	Campagnolo®	6	53
Rear derailleur pulley wheel bolt	Shimano®	2.9–3.9	27–34

Brake Caliper and Lever Area

Component	Type/Brand	Newton Meters	Inch-Pounds
Upright bar brake levers	Shimano®	6–8	53–69
	Avid®	5–7	44–62
	Campagnolo®	10	89
Brake caliper mount to frame: side-pull, dual-pivot, center-pull	Shimano®	7.8–9.8	70–86
	Campagnolo®	10	89
	Cane Creek®	7.7–8.1	68–72
	Tektro®	8–10	69–89
Brake caliper mount to frame: linear-pull or cantilever	Shimano®	8–10	69–89
	SRAM®	5–6.8	45–60
	Avid®	4.9–6.9	43–61
	Control Tech®	11.3–13.6	100–120
	Tektro®	6–8	53–69
Brake pad: threaded stud	Avid®	5.9–7.8	53–69
	Campagnolo®	8	71
	Cane Creek®	6.3–6.7	56–60
	Tektro®	5–7	43–61
	Shimano®	5–7	43–61
	SRAM®	5.7–7.9	50–70
Brake pad: smooth stud	Shimano®	7.9–8.8	70–78
Brake pad: side-pull and dual-pivot bolts	Campagnolo®	8	72
	Cane Creek®	6.3–6.7	56–60
	Shimano®	6–8	53–69
	Tektro®	5–7	43–61
Brake cable pinch bolt: linear pull & cantilever	Control Tech®	4.5–6.8	40–60
	Shimano®	6–7.8	53–69
	SRAM®	5.6–7.9	50–70
	Tektro®	6–8	53–69
Brake cable pinch bolt: side pull/dual pivot/center pull	Campagnolo®	5	44
	Cane Creek®	7.7–8.1	68–72
	Mavic®	7–9	62–80
	Shimano®	6–8	53–69
	Tektro®	6–8	53–69

Disc Brake Systems

Component	Type/Brand	Newton Meters	Inch-Pounds
Disc rotor to hub: lockring	Avid®	40	350
	Shimano®	40	350
Disc rotor to hub: M5 bolts	Avid®	6.2	55
	Hayes®	5.6	50
	Magura®	3.8	34
	Shimano®	2–4	18–35
Caliper body mount	Avid®	9–10.2	80–90
	Hayes®	12.4 9 with Manitou forks	110 80 with Manitou forks
	Magura®	5.7	51
	Shimano®	6–8	53–69
	Tektro®	6–8	53–69
Hydraulic hose fittings	Hayes®	6.2	55

Formulas for converting other torque designations into Newton meter (Nm) and inch pounds (in-lb.):

Torque Equivalencies

Newton meter (Nm)	Approximate Inch-pound (in-lb.)	Approximate foot-pound (ft-lbs)
1	8.9	0.7
2	17.7	1.5
3	26.6	2.2
4	35.4	3.0
5	44.3	3.7
6	53.1	4.4
7	62.0	5.2
8	70.8	5.9
9	79.7	6.6
10	88.5	7.4
11	97.4	8.1
12	106.2	8.9
13	115.1	9.6
14	123.9	10.3
15	132.8	11.1
16	141.6	11.8
17	150.5	12.5
18	159.3	13.3
19	168.2	14.0
20	177.0	14.8
21	185.9	15.5
22	194.7	16.2
23	203.6	17.0
24	212.4	17.7
25	221.3	18.4
26	230.1	19.2
27	239.0	19.9
28	247.8	20.7
29	256.7	21.4
30	265.5	22.1
31	274.4	22.9
32	283.2	23.6
33	292.1	24.3
34	300.9	25.1
35	309.8	25.8
36	318.6	26.6
37	327.5	27.3
38	336.3	28.0
39	345.2	28.8
40	354.0	29.5
41	362.9	30.2
42	371.7	31.0
43	380.6	31.7
44	389.4	32.5
45	398.3	33.2
46	407.1	33.9
47	416.0	34.7
48	424.8	35.4
49	433.7	36.1
50	442.6	36.9