In view of the carbon fiber parts that is becoming more common on bikes, an accurate way to judge and control the tightening torque is very important. For example, carbon fiber seat posts, handlebars, and cranksets are very popular nowadays. It is necessary to clamp these parts securely, but not over tighten them.
The dilemma with these parts is that you need to tighten them up securely to prevent slipping, but with carbon fiber parts, you risk over tightening. Steel and aluminium parts are not so prone to over tightening as they will not crack or get crushed so easily. If you hear a cracking sound while clamping a carbon fiber part, you have most likely cracked the part and it is dangerous to continue using it.
This is where a good torque wrench can prove to be very useful. It allows you to know and control exactly how much torque you want to use to tighten the part. Let us take a look at this torque wrench which I bought recently.
Torque wrench by Giant. Highly recommended by the bike shop.
Good array of bit sizes to use. Hex 3-10mm, Torx T25 and T30. There is also an extension for the M5 hex key. Some torque wrenches are cheaper, but they don't come with the bits so you have to find and buy them separately.
A little lever that can be flicked to change the direction of turning between clockwise and anti-clockwise. There is also a built in ratchet mechanism for ease of use. I was wondering why I needed to control the torque for the loosening direction (anti-clockwise) until I tried to use it to tighten my left side pedal (left hand thread).
Torque control ranges from 2-24 Nm. Easy to read gauge on the handle.
Just turn the black handle to control the torque setting. The head of the torque wrench will give way when it reaches the preset torque, to indicate that the torque has been reached.
Trying it on my Ultegra 6700 crankset!
The sticker is still there. Recommended torque setting is 12-14 Nm.
Use an M5 bit for this
I measured the current torque setting and found that it was 10 Nm, below the spec of 12-14 Nm. Adjusted the torque wrench to 12 Nm and turned it till the head of the wrench clicked.
Used it on the Fnhon handlepost with the 2 bolts on top. No idea what the setting should be, but for M5 bolts that clamp onto the handlebar, it is usually 5-8 Nm. Not so critical as I am not using a carbon handlebar.
Can also use on the chainring bolts. For this Ultegra crankset, it uses Torx bolts.
The stem bolts that clamps onto the steerer tube. 5 Nm, M4 sized.
The stem bolts that clamps onto the handlebar. Also 5 Nm.
The Shimano Saint MX80 pedals. 10 Nm, use M6 hex key on the rear of the pedal spindle.
This torque wrench may be useful, but it is probably not so important to me as I have very few carbon parts on my bikes. However, if you have a carbon handlebar/seatpost, please take note and do not clamp it too tightly. If you have already reached the maximum recommended torque spec, and the handlebar/seatpost is still slipping, then you will need to use Fiber Grip or some other carbon paste to help hold it in place.
Overall, I feel that this torque wrench is of high quality, and deserves to be used in a proper bike workshop. It is a tool that is good to have, but not necessary unless you use carbon fiber bicycle components.