This is probably also a general torque wrench question but I want to work it out so I'm installing my stem/handlebars to the right torque settings according to the manufacturer's instruction. Unfortunately the wrench manual doesn't cover this.

Behind the head of the torque wrench where the hex bit slots in, there's a switch which can be switched 'left' or 'right'. I've been getting some conflicting info online about this (and nothing specific for my wrench). Can anyone explain what it does? Set one way, the wrench seems to start 'clicking' fairly quickly even when the bolt seems slightly loose. Set the other way, it does tighten the bolt a lot, but I'm worried this is wrong since I only set it for 5.5nm and it seems to be almost as tight as physically possible.

Any help please! I don't want my stem/handlebars to crack off whilst cycling just because I've done it too tight. I don't know why shimano can't be bothered to have more than 3 paragraphs of info in English on their instruction sheet. There's only 2 switches on the wrench, one for calibration and the other behind the head. Surely they could have added a couple of extra lines so the 2nd switch/function of the wrench is explained.

The switch has nothing to do with the torque wrench function. It's just a standard ratchet wrench head, it's for forward or reverse, reverse would be used to remove or back off a bolt.

+1 the switch controls the ratchet driver for Right and Left operation. The torque values are only relevant in the correct direction, otherwise you're only measuring the drag of the ratchet mechanism.

Dude if the forward/reverse mech is confusing you. Maybe take your bike to a shop.

LOL Have to agree with that one! The right tools in the hands of someone with no training or experience can do more harm than good.

So did you use omniscience to know exactly how to use a torque wrench when you first got one at 18 off the internet which lacked instructions? Or did you go around the house experimenting with it on various items which have hex bolts? I lack the luxury of the first and I don't want the family backlash of undoing bolts from their property without having the manufacturer's torque specs for re-tightening them.

To the people who responded, thanks. I had a feeling it was that...something to do with the occasional hex heads which have a reverse direction to the usual clockwise=tighten and anti-clockwise=loosen. Although there wasn't much info online (aside from text with no useful images) like when I built a notebook and a few pcs and my Haynes Bike Book assumed a working knowledge of the wrench, I found videos on youtube so I'll give those a try since I learn practical things better from seeing others doing it.

This stuff is relatively simple compared to getting a degree in Maths and Economics or Medicine/Biochemistry, I think I can handle using a wrench without a bike shop...I just wanted some instructions, like when I use a 1000 page text book (i.e. comprehensive info) in university or a lecturer shows us how to proceed with a chemistry practical at the front of the lab before we do it...plus we have the text books for reference.

Cheers

Edit: Just re-read the thread:
I appreciate what people are saying/implying about safety, hence my concerns in the first post and asking a question online, even though I knew it would result in at least one person implying I don't have the aptitude to learn how to use a torque wrench. I've managed to install the stem, handlebars, brake levers, gear shifters, ahead compression bolt, light brackets, bell etc back on and removed the grips from the old bars (this WAS a hassle!) and put it onto the new bars. All I need to do is now tighten the stem bolts to 5.5nm with a torque wrench I just spent £50 on. I don't think I need to pay the LBS £10 just to spend 2mins tightening 6 bolts on the stem up just because I can't pull in depth knowledge of using one (Undefined on the generic instructions shimano provided) switch on a torque wrench out of the thin air.

Update:
Just saw the youtube video. My wrench made exactly the same (single loud) click sound as the person in the video for when something is tightened to the specified torque (as opposed to flipping the switch the other way where it sounds like coasting on a bike). So looks like I had installed it correctly. Lucky I didn't go and pay my LBS £10 for nothing as per advice by Bob.

I think the confusion arose for me since even when I'd switched the directional switch it was turning the hex bolt (clockwise) although it was still clicking (coasting) occasionally. I put this down to pushing slightly INTO the bolt with the wrench.

The digital fallacy.

It's important, even with accurate digital tools, to be able to estimate values so that you know when you're in the right ballpark. 5.5nm isn't very much torque. It equates to roughly 45 in/lb. Imagine a 1 pound weight hanging off of the end of a 45 in. long wrench.

Where did you get the idea that he's using a digital tool? Digital torque wrenches don't click, they beep.

Speaking for myself at least - that wasn`t the intention.

I would like to put some perspective on the situation though and again - I`ll only speak for myself. My own training wasn`t trial and error or experimentation - it was professional courses and a long line of clinics and seminars. The objective is to eliminate all risk of doing damage to any mechanical parts, any chance of compromising the safety of any customer, and getting a top quality job done in as short a time as possible.

There`s no doubt in my mind that if I asked for volunteers to provide bicycles so that inexperienced mechanics would have something to train on by trial and error - every reasonable rider would hide their high end bike in the closet and even people with department store bikes would be reluctant because ........

But for some reason lots of inexperienced mechanics have no problems volunteering their own bikes (regardless of how much they cost apparently) if it saves them a few bucks and its themselves doing the `learning`. Unfortunately for every `right` way to do something there are usually at least a half dozen ways to do it wrong and statistically - the chances of finding the correct way the first time around are pretty slim.

And although there are a number of reference books available like the Zinn book advertised on this site or the Park Tool Big Blue Book that would address most of the questions commonly asked on this site and take a lot of the risk out of the learning experience - for some reason most posters aren`t buying them and seem to prefer to take their chances.

I have a background in business analysis and risk management but even without that it makes sense to me that rather than gamble, when anything of value is at stake - it makes sense to eliminate all possible risk. I`m not sure why not everyone feels the same way but clearly they don`t.