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I always try to respect the manufacturer's recommended tightening torque when installing a bike component. Lately, I stumbled on a Shimano freewheel body that needs a tightening torque between 147 and 200 Nm as seen in the Dealer's Manual:

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I was wondering:

  1. What technique to use to achieve such a torque?
  2. Is there a way to measure it? A torque wrench such as Park Tool TW-6.2 only goes up to 60 Nm.
  3. Is this high amount of torque only needed for freewheel bodies that have a "built-in" fixing bolt? I checked another one with a separate fixing bolt and the torque needed is only between 35 and 50 Nm.
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    You'd be hard pressed to generate that much torque. In addition, because the freehub body is right hand thread, the act of pedalling will cause a freewheel or freehub body to tighten over time. A good trick to defeat the torque on an uninstall is to mount the hex wrench in a vise, place the rim on to the wrench engaging the freehub and grasp the rim to turn. You could do this for the final torque after you've installed the hub body most of the way by hand.
    – Jeff
    Jan 29 at 2:29
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    Great tip about using the vise for the final torque. I used this trick once to unscrew a freewheel, but did not think of it for screwing. Thanks.
    – olliebulle
    Jan 29 at 15:05
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    Do you know any auto mechanics ? Their tools work to higher values than the average bike needs.
    – Criggie ♦
    Jan 29 at 22:42
  • That is actually a very good point. I know car wheel nuts are usually tightened to ~100 Nm. I'll ask to some hobbyist auto mechanics I know what wrench they use. Thanks for the suggestion.
    – olliebulle
    Jan 29 at 22:53
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    My Proxxon MC 200 goes up to 200 Nm, I bought it for the wheel nuts of my car. You'd probably have to bring a conversion nut from 1/2" drive to the 12 mm hex - I don't think that everyone has one of those.
    – Arsenal
    Jan 30 at 9:22

3 Answers 3

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Shimano's torque ratings are best interpreted as a "ballpark" in the extreme high and low ranges. It's only the 2-20Nm range or so where you should respect the precise numerical value. If you have a vise, it would be best to hold the hexagon wrench in the vise and rotate the wheel about it. Otherwise, just do your best with the hexagon wrench. As Jeff points out, the pedaling torque will continue to tighten the freehub body very very hard.

Don't forget to put some good grease or antiseize on the threads before installing the thing. Unscrewing freehub bodies is hard enough as is--you really don't want to deal with rust or corrosion as well.

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You could measure your lever length and put known weights on the end.

Clamp the tool to a vise in a way that the wheel is upright. If your wheel has a 311mm radius you now need to put a 50kg to 65kg weight on its circumference to tighten to 147–200Nm. So just ask a relatively light person to put their whole body weight on it. If you are heavier you could even stand on a scale and put your weight on the wheel until the remaining weight displayed on the scale is just right.

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There is certainly a way to measure it. Torque wrenches used by car servicemen go often up to 200 N.m (and you can find even larger ones), they are just large ratchets with a torque click-type mechanism and look like this:

operator with a torque wrench, public domain from https://nara.getarchive.net/media/fire-controlman-3rd-class-fc3-william-bishop-uses-a-torque-wrench-to-verify-9ebe42

There would be no point buying such a tool for this task, but some friend or neighbour who services cars could have it.

I agree that the torque is a very high one and requires a lot of force and there is no need to get it exactly. Even the indicated range is quite wide.

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