Torque is Cheap

Torque is easy on a BMX. Get the right tool, tighten the bolt as much as you comfortably can and go ride. This doesn't seem to work so well on an MTB. More of an emphasis on weight saving means it's much easier to damage things by overtightening them, and I've found that neither of my dropper posts works smoothly if the seat clamp is done up too tight. I caved in early on in my MTB renaissance and bought a cheap torque wrench that is supposed to be good for 2 - 12 Nm, but I have had some trouble with loosening and over-tightened cassettes. When it came to swapping in a new wheel recently I decided to have a go at getting the correct torque for cassettes and brake rotors without buying a second wrench for the higher torque required. Here's what I came up with.

Hands equidistant from the hub, tool parallel to the floor for best results!

 

 

 

 

In case you need to do the same, here's how it works. The required torque is 40Nm, i.e. a force of 40N applied at a (perpendicular) distance of 1m from the pivot point (hub). My tool is 20cm, or one fifth of a metre, long, so I need to apply five times that force to the end of it: 200N. Since I also need to push down the same amount with the other hand to stop the wheel rotating, the total force I'm pushing down with needs to be 400N. Assuming you have scales calibrated for use on the earth's surface divide that by 10 to get what you need to see in Kg on the scales. So here I just push down (rotating the wheel to keep the wrench horizontal horizontal) until the scales show 40Kg (or about 90lb).

That's it! Feel free to tell me in the comments how this has saved you money, ruined your back, trashed your bike or that I've made critical mistakes in my reasoning..