Aren't listed torque spec's for carbon fiber composite frames and components maximums?

Not always, but typically, which is why you torque 'til the fastener does its job, not 'til you hit the max spec like a ham-fist.

That's ridiculous. What accuracy and precision are required? What accuracy and precision do the pricier wrenches provide? As most mechanics and many folks here will agree like Whyfi above, in bicycle work you don't tighten up to the max. spec. You tighten to the required level for the application while staying below the max. spec. Often the actual required level is only about 1/3 of the max. spec. or less. Perhaps that is different than nuclear reactors. I don't know, but it doesn't matter, does it? And then you aren't considering that the max. spec. must have a safety factor built in as well. Inexpensive torque wrenches are plenty good enough for bike work.

So for bikes, sort of or close or in the general area is good enough?

I'm used to aircooled VW engines where, the engine heats up it expands and that's when it reaches the true torque. So too tight and you snap a head stud. Too loose and you have compression loss since there's no head gasket. On intake manifolds, too loose and they tend to rattle loose and you have a vacuum leak. Too loose for a flywheel can really ruin your day.

I'd sure hate for the stem to come loose from the steerer when i'm riding.

Rightly or wrongly, I consider torque values on carbon parts to be maximums: beyond that you're likely to break it. For drive-train parts (e.g., BB and cranks) I see them as target, operational specs, much like engine parts.

The VW info really has nothing to do with what we are discussing.

I wouldn't like it either if my stem came loose. But before carbon fiber was in vogue, torque wrenches were hardly ever used on bicycles. And that didn't mean folks just cranked down on all the bolts to just short of them popping. Tight for stems, tight for bars, is all pretty easy to gauge without a torque wrench. The torque wrench really just protects carbon fiber these days. There is no reason to get anywhere near the max for stems, bars, seat posts, and saddle clamps. Now threaded BB cups and crank fixing bolts are a different story. There is a functional reason for them to be at torque spec. But even cassette lock rings don't need to be at max torque. That just strips aluminum off the threads in my experience. A good impression on the hand holding the wrench indicates it is tight enough.

Agreed.

Damaging a bung on a steel or alloy bike is much easier to fix than on a carbon bike.

[QUOTE=oldnslow2;18158080]One word:

Exactly. I have used and bought a few torque wrenches over the years and you get what you pay for. Who wants to fly on an airplane built with harbor freight torque wrenches. I have a newly opened Harbor Freight next to me and never been in there.

While I love my S/K tools and completely agree about tools being a lifetime investment (at 42 I already have some I've been using over 20 years) those are still spring-loaded micrometer wrenches you don't want to use over the whole scale or store without the tension released.

If you're going to spend that sort of money buy Stahlwille split-beam torque wrenches direct from Germany. With the strong dollar TBS-Aachen sells 730 series starting at $162 (143 Euros) and 730N for $182 (163 Euros). I paid $48 (42 Euros) for my 725B hex bit ratchet which doesn't buy a lot of quality bit sockets.

Or wait for a good used deal - on ebay I acquired my 730/2 4-20Nm wrench for $45. You can also look for VAG (Volkswagen Audi Group) and Mercedes torque wrenches which are Stahlwille plus the car company's part number.

After years of lust I acquired a 730/2 4-20 Nm, 730/5 6-50 Nm / 5-36 ft-lb, and 730/10 20-100 Nm / 15-72.5 ft-lbs which all take the same 9x12mm inserts. For inserts I have a hex bit ratchet which fits where square drives and bit sockets do not, a 3/8" 6 degree ratchet, 1/2" 6 degree ratchet, and 1/4" box wrench.

Some day I'll pickup the fixed 1/4" bit holder.



1. They're accurate over the entire scale (+/- 4% for 730 and +/- 3% for 730N on the factory calibration, but wrenches made after 2007 can be calibrated to +/- 1%).

2. Unlike other split-beam wrenches you can flip the head 180 degrees for counter-clockwise use (but must depress the insert release plunger with a small hex key or something to go back to clockwise operation)

3. On the 730 series you set torque almost instantly by holding down the lock and sliding the scale with opposite thumbs instead of cranking on the end as with a micrometer wrench. The 730N has a micrometer adjustment, except it's easy to turn since the insides aren't spring-loaded.



4. The heads interchange. 1/4, 3/8, 1/2, hex bit, open-ended wrench, box-wrench, weld a lockring tool to a blank insert, whatever. Most are setup so torque is direct-reading.

5. There's no load on the internals except when you're torquing a bolt until it clicks so you can leave them set or loosen bolts without ill effects.

You get at most what you pay for.

Airbus and Boeing planes are assembled with Stahlwille torque wrenches.

Just an FYI, I went to Sears today and looked at the Crafsman. It was very large...overkill for anything other than a crank on a bike. The adjustments were very cumbersome and not easy to understand, either. I still don't know whether to go with the Park Tools or the Nashbar option...but I definitely want a torque wrench specifically designed for bike work.

Drew Eckhardt
"Airbus and Boeing planes are assembled with Stahlwille torque wrenches."

I build 777's and use mostly Snap On torque wrenches that are calibrated regularly. My point is I will never meet the end users of my work yet they count on it getting done correctly with trustworthy processes. I would not use a harbor freight wrench there and I will not use it for my own personal needs either.
Those Stahlwille may be used in certain areas but not where I work. Those prices would chock a bean counter on the spot.

Foe most jobs...

https://www.warrenandbrown.com.au/precisiontools/product-details/320500:10-220in.lb--3$OR$8/137

And for the bigger jobs, plus left hand fasteners like BB's..

Snap on Torque Wrench 3 8 Drive | eBay

You really need two.

Hi Mayberry32,

Here's what I bought:

Park Tool TW1 (0-7 Nm) -- Handles most small torque jobs on a bicycle. 1/4" drive AND it includes a 3/8" adapter.
Park Tool TW2 (0-70 Nm) -- Handles bigger jobs like pedals, bottom brackets and gear cassettes. 3/8" drive.
Park Tool SBS-1 -- 3/8" socket and bit set (works with both TW1 and TW2).
Park Tool SAC-2 -- Friction assembly compound (prevents carbon and metal parts from slipping at lower torques).

The reason I chose the TW1 and TW2 is because they are the old-fashioned spring-type (also called "beam-type") torque wrenches that do not require calibration like the modern click-type ratcheting torque wrenches. If you try to save money with a cheap click-type, you can be fairly sure that it won't be very accurate. The spring type are much less problematic. They are usually cheaper (when comparing to comparable-quality click-types). But you may need to hurry because Park Tool no longer lists the TW1 and TW2 on their website. I think they've been discontinued. But you can still find them on Amazon and eBay.

The friction compound is very important---especially when working with carbon parts. For example, it enables you to use a modest torque with a carbon handlebar, yet the handlebar is held firmly in place. This same compound also works great for all kinds of metal parts. Some friction compounds are more gritty and abrasive than others and are more prone to scratch your parts. The Park Tool SAC-2 compound seems like a good compromise between grip and grit. In my experience, it holds very well without scratching carbon as much as some of the other compounds.

If you can't afford to buy both torque wrenches at the same time, start with the TW1 and the SBS-1 socket and bit set. That will enable you to do 90% of the torque jobs on your bike. The only ones you won't be able to do (until you get a higher-range torque wrench like the TW2) are the high-torque settings like are used for pedals, bottom brackets, gear cassettes, etc.

Finally, beware of using an automotive click-type torque wrench on your pedals or bottom bracket because some of the cheap ones only work in one direction and cannot torque a left-hand thread. You need a torque wrench that works in both directions (bi-directional) for these jobs.

Kind regards, RoadLight

Which is why I don't obsess over the torque wrenches when working on seat posts, stems, and the like. I do believe the use of a good carbon fiber specific assembly compound for such items may be more important than absolute torque wrench accuracy. Now where drive train components are concerned, I tend to be a bit more picky.

The 1/4" Nashbar torque wrench has been fine as has been the D/B t/w from Sears for the higher torque stuff.

I was just going to go with one of these.. seems to cover most anything I'd need it for on the bike?
Amazon.com: VENZO Bicycle Bike Torque Wrench Allen Key Tool Socket Set Kit: Sports & Outdoors

Were we talking about flying on airplanes?

I originally thought accuracy counts, but have since learned that when working on bicycles, close or in the general area is good enough.

So when a bolt specifies a 5mm Allen, i'll just use a 4mm until it no longer turns. That should be "good enough".

Interesting range of opinions in this thread. Arguing about 1% or 5% or even 10% accuracy while ignoring the basics is measuring with a micrometer and cutting with a ax.
I have 6 torque wrenches of various format. The T wrenches get used in various ranges and use profiles. From a small beam type used for setting floating rotors on rotor hats to a 4 foot long 300 to 600 ft/lb for center lock wheels. All 6 have something in common. The number one thing that directly affects their final accuracy is not the tool itself but all the rest. I am not taking about how they are held and how final torque is reached such as fast single pull to incremental draw in. #1 item that has not been mentioned in this thread is wet or dry torque. Is the thread chase and fastener clean and dry? yes/no? Did you put a little locktite on the threads perhaps? Ok now take your $$$ T wrench set it just right on the number to X.XX nm, carefully draw it in to spec right to the numbers and...... be 20% to 40% over.

Dirty old used bolt? Proper torque might result in under clamping force. Oily bolt? If using a dry torque value you will go past the clamping values the torque rating was intended to produce. Bolts and nuts with thread lockers are to be considered wet torque values. Dissimilar metals require adjustments in values in order to produce the proper clamping values. This is the goal. To produce adequate or proper clamping pressure without overloading the fastener. some things like water bottle cage bolts all you need is to be less than too much other things such as a con rod bolt that is drawn to a set torque value then further tightened and measured in length to set final clamping force. This format takes the wet dry aspect out and produces a very accurate final value. I use a little 1/4 drive digital t wrench on stem bolts and other small stuff in soft metals. set at a value I want to hit and listen for the beep while also using common sense AKA prior experience.

All in all if you have a lot of experience with fastners you will not need a T wrench for most things. Some things you need one every time and with the tool the knowledge of fastener usage too. If you don't have much experience a properly used T wrench is good to have to help guide. Most people make small stuff too tight and big stuff too loose.

I have one Horrible Fright torque wrench. It is the one used at the track for torquing wheel nuts. It has taken a beating as it is my one and only loaner and is often loaned out to folks that don't quite take good care of it and yet it is still in good range after many years of abuse. $12 on sale.

Get one of the small torque keys (the ~5 Nm ones). That covers the majority of common bike repairs. Everything else is usually less critical and less frequently needed. The small key is by far the most critical, since small fasteners are most likely to be over-torqued, large things are typically under torqued. The most important thing about a torque wrench is that you use it. Big wrenches are useless for 95% of bike stuff, interchangeable keys are awesome.

Are you really not getting it or are you just fighting in the hopes of not being wrong on the internet?

You have the XXX integrated bar/stem, yeah? Go look at the spec on the top left of the where you tighten it on to the steerer. What does it say? I'll save you the trouble - is says "5.2 nM MAX" Not "5.2 nM" or "5.2 nM MIN" MAX, dude. It shouldn't be that tough to grasp the concept that you need to tighten it enough to do the job, whatever that figure may be, but to not exceed 5.2. So yeah, good enough is good enough.

Three pages? You guys torque too much.

So as soon as its snug you stop. But what happens when you are out of the saddle and it moves when you're cranking on the bars?

No, as soon as it does its job you stop. If it moves when being tugged (side note: you can do this before riding [GASP!]) then it's not tight enough and should be tightened a little more, no?