Are torque wrenches really necessary?
 

I've been getting into doing my own maintenance like drive train cleaning with chains, cassettes, and chainrings off the bike and soaking them in degreaser.

I've changed a few pedals and stems before and am in the process of switching to new cassettes and chainrings.

Is it essential that I follow all the torque specs closely? When I take my bike to LBS, I see the mechanics working on things without a torque wrench. It seems they just go with their feel. They've probably done it so many times that they probably know mostly what parts requires what Nm and how much force to put in their arms by feel.

I did buy a small 1/4" drive torque wrench set that only goes up to 25Nm so I use that for the more delicate parts with low torque specs. For example, my stem indicates not to exceed 4Nm so I torque it slightly below that. The lockring on the cassette however, indicates 40Nm. I don't have a socket bit big enough to fit a lockring tool so I just try to tighten enough without going too tight (just by feel). My crankarm indicates 48-53 Nm but I go up to 25Nm with my torque wrench and then use a regular hex wrench to go some more but I have no idea what actual torque it is ending up.

Are these torque specs all essential to follow and thus a bigger torque wrench necessary? How do you guys work on your bikes?

Thanks.

Unless your hand has been calibrated, i'd get a torque wrench.

The risk of over torquing and damaging a carbon frame is just not worth it... to me.

No they are not necessary. More useful for some people than others.

IMO, not necessary and there's no reason to design and build bikes an a way that they are.

Most of the torque specs published and heeded so strictly, miss the point. Most fasteners on bikes need to be tightened enough to do the job, and n o more. For example, the toque spec given for stem clamp bolts aren't truly relevant to the task. The required torque is more related to the fit and traction between the stem and fork than anything else. Since that varies so much, it's naive to believe that a published torque has any hope of being right.

Torque specs, are useful as guides for mechanics, but with any experience, and willingness to trust your hands, the screw itself will tell you when it's properly tight.

If having a torque wrench makes you more confident, then buy it, but don't consider it a substitute for being aware of what's happening.

When I started using a 3/8ths drive Snap On torque wrench on my vehicle and torqued all the bolts to spec on the short block, the vacuum at idle increased by five inches.

I always use a torque wrench on tapered BB's and cassette lockrings.
I learned the hard way that my idea of "tight enough" was not accurate on either of these.

If you're not a hamfist, no.

I've wrenched on all kinds of stuff from bikes to cars to boats and snowmobiles and motorcycles to go karts and lawn mowers to paper converting equipment and GE gas turbine engine. My dad taught Diesel Mechanics at a tech school so every summer brought a new project. I think torque wrenches are valuable tools when you are first getting aquainted with being a mechanic but grow less necessary over time as you get the feel for fasteners. That said I wouldn't assemble an engine without one. One thing some people overlook is the importance of using good quality fasteners that are in good condition and knowing when you can re-use a fastener and when you should throw them away. A bunged up thread can seize a nut on a bolt and give you the torque spec you're looking for without actually doing the clamping work you need the fastener to do.

My favorite bit of advice to give new mechanics is "tighten the bolt until you feel it getting loose again then back off a quarter turn". Of course this is nonsense if you feel it getting loose then you've stripped the threads

My understanding is that many of the torque specs are for the screws themselves. Going above the spec risks damage to the threads. People talk about torque specs on their stems and seatpost clamps, etc.. and refer to these ratings as guidelines to avoid damage to the clamped items (ie. the handlebars and seatpost). However the obvious problem with this theory is that the seatpost clamp maker and stem maker, have no idea what model, material or make of item you're going to be clamping -- CF, Alloy, Stainless Steel, and build/wall thickness, etc..

The torque values are to prevent you irreparably damaging the actual threads of the screw/bolt itself.

I've never used one. However, years ago I learned that I could over-torque bolts enough to strip the threads in cheap aluminum parts. Since then, I have made sure to use only high-end, strongly made parts and I have not had any issues.

My confession is true. I am sure that since that time I have gotten much better at gauging torque when I tighten a bolt, but I still don't use a torque wrench. All that said, I wish I had gotten a small torque wrench ages ago, so that I would not have had to learn all this by trial and error (which means destroying components.)

........what I previously stated..........

I thought it was "tighten it until it snaps then back it off a 1/4 turn".

Well these are both clearly excellent advice! perhaps until it snaps is for course threads and strong materials and until it gets loose again is for fine threads and less robust materials.

Yes, get a good ft/lb and in/lb torque wrench and no more guesswork.

Lots of beginners over-tighten seatpost bolts and stem bolts, causing irreparable damage to seatposts and forks. If you use the smallest possible wrenches (for minimal leverage) and tend to under-tighten bolts, then maybe you don't need a torque wrench. If you're ham-fisted with lightweight components, then you do need it.

I've not put a torque wrench to a bike in my 30 years of maintaining my little stable of bikes. I got my first carbon fiber bars and seatposts in the early '90s, and often run a mix of bolt materials; my two main roadies now have Ti, aluminum and stainless bolts. Never had any troubles.

I got by for decades wrenching on stuff bikes with pliers and adjustable wrench.

If you tend to build a bike from scratch, and do most of the work/repairs at home then it could be helpful. Especially with lightweight carbon pieces.

For the standard cyclist, probably not. I just use the Ritchey 5nm tool for adjusting seatpost/stem/steerer tube. Really just piece of mind for me, but I guess it also stops me from over torquing.

Next thing people will craze about is proper torque for a quick-release skewer. It is a carbon part, proper torque must be quantified!

Back in the days of tapered bb spindles, I would occasionally have my left crank fall off. I bought a torque wrench and found that I was only torque to 1/2 the recommended value. Problem solved.

You're not going to get any consistency if you just torque by feel. Different feels depending on handle shape and length.

That said, being ballpark close is close enough; you don't have to be exact. But if you need a torque wrench just be be close, why not use one as a matter of course.

I may be exceeding the Max 16 Nm on my seatpost bolts.

If you use teeny tiny bolts on your handlebars and CF seatposts then yes.

i thought it went... "tighten it until just before it snaps then back it off a 1/4 turn". but i'm prepared to be corrected on an international public forum, ...again. :)

Most don't matter. "snug" with an appropriate length wrench is usually both enough to prevent loosening and not so much you risk breaking anything, with "appropriate length" often what standard hex-keys and combination wrenches are produced in.

Some do, or at least "appropriate length" departs from standard wrenches.

Lots of people (including some bike shop mechanics) don't get crank arms tight enough which can result in them getting loose at which point they move, open the taper they rely on for a press fit, and are ruined.

This still applies to splined cranks which don't have separate pinch bolts - they have a slight taper on the mating surfaces (ISIS used 1 degree) with installation stretching the crank arm until it bottoms against a shoulder on the spindle.

What happens when you don't get a lock ring tight enough?

Somehow, it loosens up until every time you transition from coasting to pedaling, you get a big "Clunk" as you start to pedal.