Anthony Marchand Bicycle Repair And Maintenance information And Tips

How to Use a Torque Wrench
Correct torque is just a click away

The Importance of Correct Torque:
Over tightening the bolts or screws on you bicycle can lead to disastrous results. If over-tightened, bolts or costly components may break or become damaged. I've seen the bolt that holds the seat on the post break due to over tightening while the rider was on the bicycle! I've seen expensive derailleurs break and carbon fiber seat post fracture for the same reason. Don't let this happen to you. Invest in a "torque wrench." The correct torque is essential, especially in the carbon fiber age where under tightening can lead to slippage and over tightening can lead to unforeseen cracks, breaks or disaster on the road1. One should also calibrate your torque wrench to assure correct torque force. Here are several of the types commonly used in maintenance and repair2:
  • Click Wrench:
    The user can preset the level of torque using the clutch mechanism. Once the torque level is reached, the clutch then starts to slip and one hears a click sound to indicate the required level. The wrench has a screw mechanism at the bottom which when turned, compresses a spring and sets the torque strength. We'll describe how to set the torque levels in my next video. Digital torque wrenches are also available which make the settings easier.
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Measurement units:
The measure of the force applied to produce rotational motion (usually measured in foot-pounds). Torque3 is determined by multiplying the applied force by the distance from the pivot point to the point where the force is applied. Measurements of torque include pounds-foot4 (the torque created by one pound force acting at a perpendicular distance of one foot from a pivot point), pound-inch (the torque created by one pound force acting at a perpendicular distance of one inch from a pivot point) and newton-meters5,6 (the torque resulting from a force of one newton applied perpendicularly to a moment arm which is one meter long.)
Conversion table are available depending on your torque wrench and the specifications needed (see below).

  1. How to use a Torque Wrench   Types and use of a torque wrench from tony10speed.com
  2. Setting Non-Digital Torque Wrench: (coming soon) from tony10speed.com
  3. More on Torque Wrench
  4. Torque Wrench Calibration

Know your torque specs: Many components are marked with the maximum torque on the component itself. Since this is the maximum, it is suggest to use 20% less (i.e. maximum torque times 0.8).
When torque is usually given in a range, I use the middle of the range since the high end is the point above which we can cause damage. Always check your bike for cracks or fracture of carbon fiber at the points where bolts can be tightened. Always use the correct grease on bolts, seat posts and other components. Carbon fiber grease contains elements that prevent slippage and allow a lower torque.

Online conversion tables:
Fastener (bolt) Preparation: Most of the steel fasteners we use just require a coating of grease to prevent seizing and corrosion. A few require a tread locker such as Loctite to prevent loosing. Still others go on dry. It's important to know since putting on a tread coating when a bolt should go on dry will result in more transfer of energy to the clamp or part being fastened and can easily result in damage or breakage when torquing. Consult your component insert or manufactures website.7 See addendum.

Component preparation: The contact surfaces of the bicycle components may also need preparation. I recommend using a carbon assembly paste on the contact surfaces on the component that's being torqued regardless whether or not it's made of carbon (see addendum).8 This paste forms a thin gripping layer containing compressible particle to help the part stay in place and allow using the middle or lower end of the high torque range or 20% below the maximum. However, DO NOT USE carbon prep on a carbon steerer. The consensus is to use grease on a carbon fiber steering fork.

Addendum: Fastener Preparation
Partial List 8, 9
  1. Tread locker such as Loctite* (2 reason: either may loosen under load even though torqued or bolts that require low torque such as rotor bolts or when lubricant may drip down onto critical parts. Medium strength Blue is the most common used since the part can be disassembled. Red is almost impossible to free) Avoid titanium bolts and where dissimilar materials are used. Use anti seize in such cases.
    • Brake caliper bolts
    • Stem bolts (recommended by many manufactures such a Trek)
    • Rear derailleur hanger bolt
    • Brake rotor and caliper mounting hardware are treated with it so there is little if any chance of an improperly torqued fitting rattling loose
    • Crown pinch bolts 242 Blue
    • Cantilever studs 242 Blue
    • Pivot axle bolt 290 Green
    • Pivot bushings: Frame/swingarm 290 Green or R 680
    • Shock mount bolts ( shock mountain hardware or any threaded fitting on a rotating part) 242 Blue
    • Press-On or threaded parts such as press on bottom brackets that tend to develop creaks over time (a touch of blue thread locker on the press on part) but consult your manufacturer first because you could void your warranty
    • BB threads used on some bikes
  2. Where not to use Loctite (use grease instead)
    • Chain ring bolts, especially aluminum versions (use grease to allow you to loosen them later on)
    • Most crank set bolts (grease used here allows it to attain the proper torque)
    • Pedal threads (pedals won't loosen due to their reverse threading, but using grease will eliminate creaks and make them easier to remove)
    • Axle threads on either front or rear thru-axles (grease here prevents the two aluminum surfaces from galling). Using thick grease here will prevent loosening and make them easier to remove.
    • Titanium bolts (use anti-seize compound)
    • *Parts must be clean and dry, with no grease, oil or dirt before application. Apply before assembly, attach and torque. Then let dry for 24 hours to cure. After loosening a threaded fastener that has Loctite, the Loctite bond has been broken. For this reason, Loctite must be re-applied.
  3. Anti seize compound: Antiseize is basically oil with copper powder (or nickel) and graphite added in. Please It is a compound NOT a lubricant. Warning: It's very messy! Use anti seize with a small brush, one for applying soldering flux and lube to small parts.
    • Titanium bolts (copper based antiseize)
    • Ti parts into titanium components
    • Ti bottom brackets
    • Aluminum bolts with Aluminum threads would be best kept from oxidation of threads if a nickel base anti seize is used, same with steel to aluminum or stainless steel to aluminum or Vs. Versa. Ref: Road Bike Review.com  See last blog, bottom of page. Also when installing aluminum bottom bracket cups.
  4. Carbon parts can be assembled dry, but I recommend a Fiber Assembly Compound such as Finish Line Fiber Paste on all carbon parts even when carbon is being fasten to Mallory parts. I've seen to many instances where a seatpost put in dry could not be removed.
    • Apply on one surface such as the seat post or handlebars. Apply to only one surface and use a thin coat.
    • Do not use on for fork steerer (here most recommend grease).10 Here, carbon prep can work it's way down the stem and gravity, heat and vibration work together to allow the carbon prep to mover into the headset. Carbon prep is somewhat abrasive and due to slight motion involved with the headset, carbon prep can wear away steer material, causing the fork to loose strength.
    • Comment from Hiaruga concerning carbon fiber assembly components:
      Word of caution using carbon fiber grease--with silicon particles in the compound, I find it scratches the surface of the seatpost or handlebar.

      My response:
      You are correct, some carbon assembly compound may scratch and sometimes put dents in the carbon components even when torqued below the maximum or in the mid-range. Comments on the internet suggest that the size of the particles in the compound may be the culprit. Park Tool Supergrip Carbon Compound seems to have the largest particle with the most complaints by users when scouring the internet. Finish Line Fiber Grip or FSA compound seem to have the smallest particle and maybe a better choice. Motorex Carbon Grease does not rely on particle and may be the best, although I haven't tried it yet (available from Merlin Cycles and Amazon) Ref: mtbr forums 

      Cycling garu Lennard Zinn suggests using grease on a carbon fiber seatpost and has not had a problem. Ref: Technical Q&A with Lennard Zinn – More greased carbon  from VeloNews.com Despite what some mechanics say. What you don't want to do with a carbon seatpost is put it in dry.

      I use Finish Line Fiber Grip but will try the Motorex Carbon Grease. I'd like to hear what others readers think. Thanks for the comment, Tony

  5. Grease: Pretty much everything else. MOST threaded fasteners to prevent corrosion or seizing. Any small hardware that hasn't repeatedly loosened (M3 sized bolts or smaller. Use only a thin film.
    • Most non carbon/non titanium component bolts except where mentioned under "tread locker" (Loctite)
    • Chain ring bolts, especially aluminum versions (use grease to allow you to loosen them later on)
    • Most crank set bolts (grease used here allows it to attain the proper torque)
    • Pedal threads (pedals won't loosen due to their reverse threading, but using grease will eliminate creaks and make them easier to remove)
    • Axle threads on either front or rear thru-axles (grease here prevents the two aluminum surfaces from galling)
    • For assembly of unlike metals (steel into aluminum)


References:
  1. Workshop: Why torque wrenches are invaluable   from BikeRadar
  2. 6 Types of Torque Wrenches Explained   "from do-it-yourself."
  3. Torque   from Wikipedia
  4. Pound-inch   from Wiki answers
  5. Newton (unit)   from Wikipedia
  6. Newton meter  from Wikipedia
  7. Lubrication and Treaded Fastener Preparation. from Trek
  8. Proper Torque Wrench Use from Art's Cyclery.
  9. Thread locker Basics by Mike Levy, from Pinbike Teck, Aug 2011
  10. How & Where To Use Grease, Fiber Grip, Thread lock + Anti Seize On Your Bike  from GCN, Dec. 2014

Torque Wrench
Anthony Marchand bicycle repair and maintenance information and tips.

  • The Beam Wrench:
    This is a very simple and basic type of torque wrench. The wrench head and handle are separated by a lever arm. The lever arm has a certain level of elasticity which allows the torque wrench to bend slightly at the level of pressure. The indicator remains parallel with the arm when the torque wrench is not in use or no pressure is being applied. Once torque is being applied, there is a scale which moves to give a reading, much like a weighing scale with a needle pointer that indicates the weight of the product.

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