Use of Beam Torque Wrenches, Park TW-1 and TW-2

The Park TW-1 and TW-2 are simple in their operation. Both tools are accurate and durable. The TW-1 is a 1/4 inch drive, and the TW-2 accepts 3/8 inch drive sockets.

On either tool, the larger steel beam or rod flexes as you tighten any bolt. The more force you apply to tighten your bolt, the greater the steel beam will deflect. The smaller beam with a pointed end does not deflect. It is a reference for the larger beam.

To check tool calibration look at the pointed indicator when you are not tightening a bolt. If it is pointing at 0, it is accurate. If it is off, bend the indicator unit until it points at 0. Park wrenches are accurate both for both left and right hand torque. The beam will never fatigue and lead to inaccurate readings. For greatest accuracy, use a thread preparation, either grease, lube, or an appropriate grade of Loctite, on the threads of the bolts you wish to tighten.

See Recommended Torque for more information regarding torque settings for various bicycle components.

 
 

TORQUE and TORQUE WRENCHES

Nuts and bolts are held together by tension or elasticity. Threads provide a continuously inclined plane, which creates a wedge for the bolt when you tighten the nut. Like a rubber band, metal is elastic, and will stretch a little as you tighten a nut. If you overtighten a nut you will go past the limits of the metal's elastiticity and strip the threads. If you under tighten, the bolt will not stretch and thus will loosen more easily through normal use. A torque wrench allows you to tighten the bolt and nut to the correct tension, so it will stay in place without loosening.

Torque is simply a twisting or turning motion around the axis of the nut or bolt. Torque wrenches measure resistance to rotation. This resistance can be correlated to, but is not a direct measurement of, fastener tension. Generally, the higher the resistance to rotation, the greater the tension on the threaded fastener.

Typically, lubrication is desired in the thread and at the bolt head. Without lubrication, a higher twisting resistance is felt by the torque wrench. The torque wrench reads only this resistance to rotation, it does not directly read the tension in the bolt. Consult the component/bicycle manufacturer for proper thread preparation if in doubt.

Another option for thread preparation is a thread locking compound, such as from Loctite®, Wurth®, and Devcon®. This is a fluid that is applied to clean threads. The fluid provides some lubrication during torque. When sealed from air, the fluid hardens and expands as it cures. This provides resistance to loosening and also forms a seal to water and corrosion. Thread locking compounds can be useful when parts cannot be fully torqued. For example, older aluminum chainring bolts should use a thread locker as they cannot be tightened as much as steel chainring bolts. Newer alloy chainring bolts are cut from 7000 series aluminum and are almost as strong as steel ones. Thread lockers should not be used to replace proper torque and thread pre-load when clamping load is important. Generally, the service removable grades are used, such as Loctite® #222 or #242.

Cross threaded parts will cause more resistance than correctly aligned threads. A torque wrench is unable to distinguish this problem. It is the responsibility of the mechanic to check thread alignment.

It is important to understand torque unit specifications. For example, securing crank arms to 25 inch pounds is not the same as securing it to 25 foot pounds.

The most common reason for threaded fasteners loosening is simply that they were inadequately secured during initial assembly. Vibration, stress, or use/abuse usually will not cause a properly sized and secured threaded fastener to loosen.

Below is list of available bicycle specific torque specifications. Some manufacturers do not specify torque for their product.

In the USA, the common unit used to measure torque is the inch-pound. This is a force of one pound acting at the end of a lever (wrench) only one inch long. Another unit is the foot-pound, 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. 12 inch pounds equals 1 foot pound. Because it can become confusing, it is best to stick to one designation. Park Tool torque wrenches are calibrated in inch-pounds.

All figures are inch-pound. Some companies do not specify torque for certain components or parts.

Component	Shimano in-lb.	Barnett’s Manual Recommendation	Other- in-lb.
Wheel, hub, rear cog area .	.	.	.
Spoke tension	n/a	n/a	Spokes are measured with tension, not torque at nipple. Contact rim manufacturer for specific tension recommendations
Quick release-closed cam type	n/a	n/a	Measured torque not typically used. Common industry practice: Resistance half way through swing
Axle nuts to frame (non-quick release type wheels)	260-390	Front 180-240 Rear 240-300	Sachs 312 Control Tech 65 (steel) Control Tech 85 (titanium)
Cassette sprocket lockring	260-434	265	Sachs 354 Campagnolo 442
Hub cone locking nut	87-217	120-180
Freehub body	305-434	310
Headset, handlebar, seat and seat post area.	.	.	.
Headset locknut-threaded		300	Tange-Seiki 217 Chris King Gripnut type 130-150
Stem binder bolt- quill type	174-260	145-180	Control tech 144-168
MTB handle bar end extensions		120-145	Control Tech 144
Stem binder- threadless type		85-double bolt 100- single bolt	Control tech 120-144 Syncros cotter bolt type 90
"Grip Shift" mounting screw		20	Sachs 13-22
Handlebar binder	174-260	120-145 if 6mm thread 205-240 if greater than 6mm thread	Control Tech 120-144
Seat rail binder	174-347	120-145 single bolt 85-95 double bolt	Control Tech, 2 bolt type 144 Control Tech, single bolt 300 Syncros each 45
Seat post binder			Campagnolo 36-60
Crankset and pedal area .	.	.	.
Pedal into crank	307 minimum	300-360	Ritchey 307 Campagnolo 354
XTR crankarm bolts	357-435
Crankarm bolt (including spline-type cranks and square-spindle cranks)	305-391	390 max.	Sachs-336 max. White Ind.- 240-300 Syncros-240 Campagnolo-312-324
Chainring cassette to crankarm (lockring)	443-620
Chainring bolt- steel	70-95	50	Sachs 53 Campagnolo 84-120
Chainring bolt aluminum	44-88
Bottom bracket adjustable type	609-695	300- left lockring 360 fixed cup (using Loctite #242 on fixed cup)
Bottom bracket cartridge type	435-608	260-350	White Ind. 240 Real 432-612 Campagnolo 612
Derailleur and shift lever area .	.	.	.
STI type shift lever binder	53-69	50
Shift lever- MTB "thumb type"	22-26	20-25
Front Derailleur clamp mount	44-60	40	Sachs 26-36 Campagnolo 61
Front derailleur cable pinch	44-60	35	Sachs 44-50 Campagnolo 44
Rear derailleur mounting bolt	70-86	70	Sachs 54-72 Campagnolo 133
Rear derailleur cable pinch bolt	35-52	35	Sachs 44-53 Campagnolo 53
Rear derailleur pulley wheel bolt	27-34	20- alloy	Sachs 44-53
Brake caliper and lever area .	.	.	.
Brake caliper mount to frame, side/dual/center pull	70-86	70-85	Cane Creek 72-84
Brake caliper mount to braze-on	44-60	25 with mild thread locker	Control Tech 100-120
Brake pad- threaded stud, cantilever or sidepull	53-69	50-60
Brake pad- smooth stud, cantilever	70-78	70-80
Brake cable pinch bolt- cantilever	53-69	50-70	Control Tech 40-60
Brake cable pinch bolt- sidepull/dualpull/centerpull	53-69	50-70	Cane Creek 68-72
Brake caliper arm pivot- dual pivot	70-86	50-70	Cane Creek 72-84
Sidepull/dual pivot brake pad bolt	44-60	50-70	Cane Creek 56-60
Cantilever straddle wire pinch 5x 0.8 thread	35-43	50-70	Control Tech 40-60
Brake caliper straddle wire pinch 6 x 1 thread	50-75	50-70
Brake lever-MTB type	53-69	35-60
Brake lever-drop bar type	53-69	70-85	Sachs 88 Campagnolo 88

TORQUE EQUIVALENCIES

Formulas for converting other torque designations into inch pounds (in-lb.).

in-lb. = ft-lb. × 12
in-lb. = Nm × 8.851
in-lb. = kgf-cm / 1.15