2008 Syntace Torque Wrench w/Bit Set
With not only safety, but dollars on the line, taking some insurance in the form of a torque wrench makes good sense. So long as you know the proper torque spec and follow the assembly directions, you should be within the tolerances of the components. Tight enough not to move or creak, not so tight as to destroy threads and crack parts.
Carbon fiber bike parts breed fear in some and paranoia in others. The fear of catastrophic failure is bit exaggerated but reasonable. While most carbon fiber parts are stronger than their aluminum counterparts, they can be destroyed by setting them up improperly. Under-tightening can lead to slippage, the slippage can score the handlebars or seat post and there's no telling if the scoring will lead to failure. Most likely won't, but when it's your life, "most likely" shouldn't be good enough. Over-tightening can lead to fracturing, and is equally bad.
We tested out the Syntace 1-20Nm Torque Wrench and Syntace Allen Bit Set. The wrench is 220mm long, has a 1/4"-drive ratchet at the head, and the bit set has an adapter and Allen bits from 2-8mm and a Torx T-25 bit as well. If you want to use this on hexagonal bolt heads, conventional 1/4" drive sockets can be used as well.
While people opening talk about their fears of carbon fiber failures, they should be concerned about ultra-thin wall aluminum as well. No, the failures most likely won't be catastrophic, but the failures could be dangerous all the same.
There are two styles of torque wrench. The beam style, manufactured for bikes by Park Tool, and the click style, by Effetto Mariposa, Pedro's and Syntace. We've already tried the Park, and now have given the Syntace a thorough test.
The click style has a number of obvious pluses. It's compact. It's easy to operate. It has a ratchet for speedy tightening. And with the click you can feel and hear when you've reached the limit. The click is created by a pivot and spring. The spring sits inside the wrench handle. At one end is the knob adjuster that is linked to the torque chart on the handle: dial clockwise to increase torque, dial counter-clockwise to reduce. At the other end of the spring is the wrench head where the spring sits against a pivot. Once the force on the pivot is greater than the spring resistance, the click occurs and you've reached the torque dialed on the handle.
The drawback of the click style is that the wrenches need periodic calibrating. Syntace sends a "Pruf Zertifikat" along with each wrench. It says when it was calibrated and what the tolerances are. While knowing the date is nice, the key is when you started using the wrench. We wrote down the date on the certificate and left it in the plastic carrying case. You should get it calibrated every two years based on the day you started using the wrench. You can send it back to Syntace, but even they don't recommend this. It's better to find a local or regional site for the calibration. Call a local auto parts store or check the web for shops that calibrate torque wrenches. The store we called quoted $45 and a 3-5 day turnaround.
For bike components, there are two sizes of torque wrench. A smaller one that takes care of fasteners and clamps, and a larger one that takes care of bottom brackets, cranks, and lockrings. Typically, people over-tighten small bolts and under-tighten large ones, so having both can be a good thing.
Nm is the abbreviation for Newton-Meter, a moment of torque created by applying one Newton of force on the end of a lever one meter from the pivot. There are also pound-inches and pound-feet, though are commonly referred to as inch-pounds and foot-pounds. 1-20Nm is also the same as 1-180 inch-pounds. We recently read a description of how to learn to measure force without a torque wrench. Put your thumb on a bathroom scale and push down while watching the numbers move. This might be ok for quick release levers, but not for tightening handlebars.
The most critical place to use a torque wrench is the steering elements. Crushing a steerer tube or cracking handlebars, or stripping threads out of a stem are all dangerous things. Unfortunately, not many companies print specs on the stem. It could be because the handlebar dictates the limit that one can torque the stem bolts. Interestingly, more and more seat collars come with torque limits stamped on them. Campagnolo stamps torque specs on their seat post clamp, and also stamps torque values on their cassette lock rings and Ultra-Torque cranksets. SRAM puts it on their cassette lock rings. FSA's K-Force Carbon Fiber stem has torque specs printed on it. With Shimano, and just about everything else consult the owner's manual for your components.
Campy makes a big deal out of torque specs. Which, when you consider their production of ever-lighter parts, their concern makes sense. They even have denied warranty claims if it looks like the part was severely over-torqued. That noted, the pinch bolt on the carbon fiber plate of the Record and Chorus rear derailleurs takes as much torque as an aluminum plate.
If you want a handy chart, visit Park Tool's website. They have a chart that can be printed out and saved. A nicer chart comes with their torque wrenches -- it has a drawing of a mountain bike and road bike and points to each section of the bike and the generally recommended torque spec. However, all charts have their limitations. The drawing referenced does not account for different component manufacturers recommendations and the web chart doesn't specify all parts or the manufacturer's recommendations along with them. In the long run, it would probably be best to consult owner's manuals and make your own chart. Some parts call for threads to be dry, some greased with a thin chain lube, some with bearing grease, and others with thread-locking compounds. A new trend is for assembly paste to be spread on clamping areas; this has the potential to reduce torque values, something we will address at another time.
We first went around our bike checking how tight the small bolts were. We wanted to know if we had under-tightened anything. Seemed like we hadn't. We were intrigued by the thought that we might have over-tightened our brake pinch bolts as the fear of slipping cable under hard braking often has us putting a fair amount of force onto this small bolt. The click-style can't tell us if we over tightened these bolts, and since there is no harm in over tightening something if you don't strip it, we were probably over-tight but under the thread limit.
We then had to do some part swapping. We switched stem, bars, brake cables, and housing. We tightened everything using the torque wrench. It was easy and re-assuring when we torqued to the limit and stopped. No second-guessing, no going back and doing a second round of tightening. We particularly like the confidence it gives because we're less likely to feel like we need a day of riding easy just to make sure nothing was set up too loose.
The Syntace bits are nicer than the bits we typically find in an auto-parts store. The size of the Allen heads is on each bit so it makes finding the right size easy and fast. The shape is not a traditional Allen head, but something called Hex Plus. Hex Plus has closer tolerances and a slightly concave shape between hex points. This allows for more metal-on metal contact, which increases strength and reduces notching -- though if we stay within the proper torque specs, we shouldn't have any worries to begin with.
We like the Syntace Torque wrench. It's easy to use and confidence inspiring. We like relying on it when installing carbon fiber seat post and bars, and when pushing a crankset onto a bottom bracket spindle. It is worthwhile for the confidence it instills.
However, it's not everything. As we saw with the brake pinch bolts, we have learned in many places how to snug bolts pretty tight without over-tightening. Admittedly, one place where we had a long learning curve was on cranksets; for a while, we over-tightened, then under-tightened, and now with a torque wrench, we always get it right. .
There are, effectively two sets of wrenching ideals. Setting up everything perfectly to spec in a shop and making sure a bike ready to ride -- the racer or race mechanic 30-second check. For the former, having a torque wrench is a great benefit -- especially with expensive parts. For the latter, you pretty much squeeze the brakes hard, twist the bars, stem and saddle, spin the wheels and go. It is possible that people can "learn" what tight is, though we'd be uncomfortable if an inexperienced home mechanic tightened our expensive carbon components.
As with so many things in life, how important a torque wrench is depends on what you conclude after reading yourself. We hope we've given enough information for you to inventory your skills and mindset and come to the right decision.