# How do I properly torque a track cog lockring?

I see a torque rating is stamped onto a lot of track cog lock rings:

However, I cannot find a way to use a torque wrench when tightening the lock ring. All the tools I've found, like Park Tool's HCW-17, are for hand use.

Are there any lock ring tools that can be used with a socket so that I can attach a torque wrench? Or is guessing the torque by feel the only option here?

A torque specification is not just a torque-spanner setting but a physical property. That is, there are many ways to apply the correct torque.

In this case it means more or less: pull it as tight as you could. One can conclude this from the high torque value and wide torque range.

To illustrate this let's find the force F you need to apply to a tool to get the torque t.

The spanner you used as an example is 30 cm long. Since you need to grip it you cannot use its whole length for leverage. Let's calculate with l = 0.25 m.

t = F l

F = t / l

For the minimum torque 40 Nm we need a force of 160 N and for the maximum 65 Nm it is 260 N. That is the weight force of 16 kg and 26 kg, respectively.

The limit to over-torqing the lock ring is either your strength or pain in your hand as you begin to crush its bones on the narrow handle of the tool.

One more thing: with bike specific quality tools, especially from manufacturers who are long in the market, you can assume the tool was built to fit its purpose. That means also that it has just the right length and shape that a professional mechanic (who tends to be strong) intuitively uses it with the right torque.

• Before the luddites chime in: torque wrenches are important and I wouldn't work on my carbon steerer or my handle bars clamp without. When the limit is 6 Nm one cannot build a tool flimsy enough not to over-torque. The same applies whenever tight torque specifications are given. However, I shouldn't trust most consumer grade torque spanners for this either (calibration). Jul 17, 2020 at 8:09
• The wrench will slip out of the notches before you can over-torque the lock ring. 40-60Nm is quire a wide range. Jul 17, 2020 at 9:07
• I don't even think I could achieve 40Nm with that wrench. Maybe in leather gloves, but I am dubious. Jul 17, 2020 at 10:40
• pain in your hand as you begin to crush its bones on the narrow handle of the tool I suspect I'd have issues with the flesh on my hand getting all cut up and bloody thereby causing my grip to slip long before my bones are crushed. ;-) Jul 17, 2020 at 14:09
• @gschenk HTFU for just a flesh wound, you say? :-D Jul 17, 2020 at 14:20

When the torque is only specified in Newton-meters I have to consult a reference, but for foot-pounds, that's the number of pounds of pressure you'd put on a one-foot lever.

For the above wrench, measure it -- I'm guessing it's about 6 inches long (probably a hair less, since you'd measure from the center of the nut, not to the end of the wrench). So you'd want to apply about twice the stated foot-pound value to the end of the wrench. This would be 60-90 pounds. You can, to familiarize your arm with that amount, lift a bag of fertilizer or some such that weighs near that. Then apply that much force to the wrench.

(As stated elsewhere, this will likely be about the most force you can apply with your arm.)

• For Newton-meters, that's roughly the amount of kilos you put on a `10cm` lever. That's precise to 2%. Jul 17, 2020 at 14:50