Do I need a torque wrench?

[FAswad]

I will be installing the new Ultegra crank when it arrives hopefully sometime this week.

I am starting to wonder though, will I need a torque wrench for this? the technical document says different bolts require different torques but the range (0.7-1.5 - 35-50Nm) appears to be wider than most torque wrenches will accomodate. This effectively means one would need to own two wrenches for bike maintenence.

I have always tightened my cassette lock rings, BBs, pedals, handlebars etc on intuition. so I am wondering is it a necessity for general bike maintenence? or is it only for the most pedantic? Is it only an issue where carbon fiber is the bike in question, or is it also a must for alloy?

and also, is there a wrench that accomodates the wide rtange required, or does one need to have two.

[weiyun]

40Nm is quite a lot of torque... With a 33cm lever, that's 120kg of weight applied at the end of the wrench.

[T-Bone]

The really low torque (0.7-1.5) is done with a small plastic tool where there isn't much chance of overtightening. For the other bolts you should be fine.

I've got a 1-20Nm torque wrench, though i only really use it for lightweight parts that have low torque ratings and carbon components. I don't think there's a wrench that will cover the required range, so i think you'd need to have 2.

Anyway, i don't think you'll have to worry with the ultegra crankset, just tighten the pinch bolts on the non-drive arm evenly.