[Closed] Torque Wrenches — Are they necessary?

No, not on bikes. They're mainly there to prevent people from over tightening steel screws/bolts into Alloy components. With a bit of care and feel you can tighten things up perfectly fine without. If you're worried then you can always give things a bit of a check after a few rides to be sure they're not coming undone - probably good practice anyway.

edit - on the creaking have you tried a squirt of WD40 in the area you're suspicious of? I doubt the 'wrong toque' is causing it unless its too loose, which you'll be having other issues too. You could always give things a bit more of a nip up to be sure.

no

For balance....

I'm a professional Engineer and I can confirm that the torques specified for bolts on your bike are there for a reason. Those torque values are the best/only way for us Engineers to be sure that the bolts are tight enough/not over-tightened.

We take into account the material of the parts being fixed together (Yield strength etc...), the bolt material, the head size and the likely compression of the parts in the joint.

We calculate the bolt torque to give sufficient clamp load to hold the joint together. We consider the head diameter of the bolts - to check that the head won't compress the parts being fixed and thus lose tension from the joint. We consider the vibration and all external loading on every fastener and joint and all this to ensure that once tightened it won't come loose.

IF the joints are tightened under our control we even loosen some to check that we get a minimum torque on a statistically significant number of joints. We plot these values on a graph and watch the trends too!

Based on all of that hard work - please feel free to nip them up as tight as you think is reasonable and don't waste your money on a Torque Wrench 😀 8)

It's all held together with some FSA thing which seems to work like a Hope Head Doctor.

Whatever the FSA thing is, it's not holding it all together, it's. The stem clamped to the steerer is holding it all together.

If your'e unsure & haven't got a feel for 'tightness' 😆

Then use one.
If your'e an old school fitter like me & a fair few on here, you probably don't really need one.

Split the difference....They're functionally useless for general spannering, but if you have a persistent creak then you have to drag one out and verify the torque spec.
A creak is always going to have multiple possible causes. Knowing that the bolts are done right is an important step in sorting it out.

As far as torque wrenches go I wouldn't recommend the one I have just because I have no idea how accurately calibrated it is [because it sits in the tool box for years at a stretch]. One that can be calibrated and adjusted accordingly sounds like a good idea.

5 knuckles tight on everything never failed me 😯 well only once 😉

They are certainly helpful. Having said that most likely culprit for squeaky is dry joints, so a bit of grease or copper slip prob best way to sort it. We prep race bikes here so always using torque wrenches and often use them on cycles but most of the bolts, on cycles, that we have had problems with have been where we used a torque wrench so I reckon many of the recommended figures are too high. Always remember to grease a bolt before torquing to get the right setting or where appropriate (ie rotor bolts, chain ring bolts etc..) use lock tight both to lube the thread when tightened and lock it once done.

If you want to do the job properly, then I think you should use one.

Few people could set up the pivots on a FS for example, unless they did it very often.

Usefull but only if calibrated properly. Ours at work used to be done every 6 months. But now we have to check the torque before every use on the analyser. Mainly due to people dropping them and mistreatment

yes you need one for softer metal parts you don't want to rip to shreds...

I've been using a Norbar torque wrench for years now, just for piece-of-mind.

I sell carbide cutting tools for a living and we always recommend to our customers to use a torque driver for tightening tool screws, the difference from engineer to engineer on how tight something should be is vast. Sometimes the insert/screws have come loose due to over tightening (stretched threads)

Genius couple of answers up there from JAG, (an engineer explaining the critical calculations made in designing a joint) then 2 replies later, esselgruntfuttock a time served fitter, (just whangs it up as tight as he feels). Ace. 😆

Wiggle have a Ritchey torque wrench for £15 that is set to 5NM for stem bolts. Bit of a compromise if cost is an issue?

I think easel meant that after a while you can closely estimate a torque value. I reckon I could give you within 5nm.

Well OK, but I'm not sure I believe you, (and I'm more of a whanger for anything over an M6, and a mechanical engineer to boot).

I have just spent the afternoon building a bike for and with my nephew, and his new torque wrench, and after every bolt tightened I heave heard "HOLD ON LETS SEE WHAT THE CORRECT TORQUE IS FOR THAT BOLT! Oh its done up correctly". Its been a funny afternoon though 😀

So for the inexperienced yes. For the professional who is liable for their work yes. For those with experience maybe not.

NB I was taught by my old man (who died in '97) how to do it.

I'm amazed at the variety of answers! JAG has it, Essel - I kinda know where you're coming from. When I was a full time mechanic, I gained a 'feel' for certain and most often used torque values but would always check them with a calibrated torque wrench - backing off and re-tightening in sequence if I had pinched up too tight.

I find my FS works much better when the pivots are at the correct torque value too 🙂

Why compromise expensive parts or a frame, or your own safety and peace of mind are further reasons for following values and sequences. 😕

Most bike parts aren't space ships - they're steel bolts into steel or alu. So if you've got no feel for torque and tightness, sure - they're a good idea. But the only time I use one is the special 1.1Nm 1.5mm Allen key I use for tightening the tiny grub screw in a Schlumpf drive.

A badly calibrated torque wrench is worse than none at all. In my experience, the most accurate torque wrenches that don't cost a mint are the old-fashioned bending-beam type.

[i]I think easel meant that after a while you can closely estimate a torque value. I reckon I could give you within 5nm.[/i]

Ha ha, brilliant! I have a torque wrench & the last time I used it was on some Race Face cranks onto an Isis BB (32nm?) The last time before that was on a Diesel Sierra cylinder head (it was in ft/lbs & can't remember what it was!) but anyway, since then I've stripped nowt, & nowts come loose!

My main gripe with torque wrenches is.

Which value to take..... That of the stem - that of the bars ? ThAt on the collar , that of the seat poat ?

Certain items have a torque value on the, thatcserves nothing more than as a warrenty get out clause- ritchey im looking at you with your 5nm seatpost clamp torque.

I have a torque wrench at work - it goes to about the region of 50k ftlbs for the stuff i do but can go faster 🙂

I read somewhere that even experienced mechanics, when asked to do a bolt up to 5nm, varied wildly with some out by a factor of 2 - both too tight and too loose.

I've got one of those ritchey 5nm torque things. Assuming its accurate, I've been under-tightening bolts for a long time! Never had any problems though.

Your creak is probably not bolt torque. Take the front end apart and clean everything well. Put it back together and sometimes that'll cure it.

Torque to what's being clamped onto. E.g. bars or seat post. Imagine you've got a carbon bar that's torque to 4nm, and the stem says 10nm, you're likely to crack the carbon if you go to the stem spec.

Unless you also specify temperature and lubricant to use, specifying just the torque is a bit pointless anyway. 5Nm with Teflon grease is a lot tighter than 5Nm unlubricated.

Creak is likely to be, headset bearings dry, bearings in the cup dry apor dirty, steerer coming loose, stem bolts dry.

Like above, unlikely to be torque, unless you've cracked the steerer or bars, which you'll see easily.

Disassemble and clean, grease, reassemble.

I had a similar problem and eventually traced it back to the brake cable outer going into the housing on the top tube. Some light grease every so often stoped the noise

OP, if your fork has QR dropouts, check that the skewer is tight.

Rickon very good but clamping force is proportional to area

Thin faceplate 2 bolt stem exert more clamping point load force to bar than a 4 bolt wide face plate stem . How can you then give a bar - a non threaded item a torque - as i said sometimes there purely to cover manufacturers arses. And you need to think about it more than just blindly following a torque value given as ive yet to see a proper torque specification on a bit - its just a number normally - as ben says lubricant makes all the difference.

Whatever the FSA thing is, it's not holding it all
together, it's. The stem clamped to the steerer
is holding it all together.

You're quite correct in theory. In practice, some combinations just don't hold and play will always develop. The right Loctite can help in those circumstances.

I'm a professional Engineer

I'm rather surprised then that you didn't mention the importance of regular calibration.

If you're not doing that (and I'm yet to meet an mtber who does though no doubt stw will provide one) then it's a pretty pointless exercise particular given people's propensity for dropping tools, etc. Not to mention the other factors mentioned above eg lube, temperature.

I thought you shouldn't use expanding devices (like a Head Doctor) with a carbon steerer?

That's exactly the sort of device you should use for carbon...

Had a similar issue with my XT cranks - always had an annoying creak but was really worried about over-tightening the bolt on the non- driveside arm.
Borrowed a torque wrench from a mate, nipped it up, problem solved.

I'm going to get one - worth it just for the peace of mind and to reduce the amount of time faffing with trial-&-error type solutions

I recently bought an Icetoolz torque wrench from Halfords to build the new carbon road bike.
To spend hundreds of pounds on lightweight carbon parts, then take a guess at how tight to do the bolts up for the sake of £25 seems a bit silly.

That said. After checking the torque on the bolts of other bikes in my garage. They were all done up well below the recommended Nm.

Your asking the wrong question. You're asking us to determine your risk appetite and only you can answer that.

Every home mechanic, by skill or good fortune, on here has tightened bolts enough so they don't loosen or break... They say as much above.

Every engineer is taught that torque is important, and of course in many applications it is, it can be life and death.

I've been riding, home mechanic 20 years and went with the home mechanic view for about 18 years, then under tightened a stem bolt resulting in the carbon bars twisting on a trail, taking a tumble, breaking two ribs. You'd think this would make me say I now am onside with the engineers... I'm not. I sit firmly on the fence. Most of the time I still trust my fingers to get it right but at the end of the job I do now check torque.

It's your risk appetite!

http://forum.slowtwitch.com/cgi-bin/gforum.cgi?do=post_view_flat;post=3345080;page=1;sb=post_latest_reply;so=ASC;mh=25

If you have fifty quid needing a new home then go pick one up.
I have one and use it all the time but did just fine without it. No stripped threads and no components coming loose on the trail.

http://www.enerpac.com/en/torque-tightening

Indeed i would say they are most important when it comes to carbon, your more likely to under tighten carbon for fear of breaking it and thats where the problem will come. Try this its basic but cheap [url= http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_categoryId_242558_productId_920043_langId_-1?istCompanyId=b8708c57-7a02-4cf6-b2c0-dc36b54a327e&istItemId=xtapwlmrw&istBid=tztx&_$$ja=cgid:5302137724%7Ctsid:35522%7Ccid:119462284%7Clid:18283950120%7Cnw:search%7Ccrid:21270118204%7Cdvc:c%7Cadp:1o1%7Cbku:1&gclid=CJOtzteyoLsCFafnwgod_AYAwQ ]Topeak Torque Wrench[/url]

From what I have read elsewhere the importance of the correct torque setting has come from the use of carbon parts. Whilst over-tightening of anything has its own problems, I have seen some crushing of very expensive parts, especially handlebars, due to over-tightening.

We take into account the material of the parts being fixed together (Yield strength etc...), the bolt material, the head size and the likely compression of the parts in the joint.

We calculate the bolt torque to give sufficient clamp load to hold the joint together. We consider the head diameter of the bolts - to check that the head won't compress the parts being fixed and thus lose tension from the joint. We consider the vibration and all external loading on every fastener and joint and all this to ensure that once tightened it won't come loose.

Uhuh.
This is what happens on bikes.
The Guy who has to write the guff on how to use the component asks the guy who designed the component what torque a bolt needs to be done to. He asks this question because he's noticed all the other companies have these numbers so feels he should add them too.
The guy who designed it then responds in one of two ways, he either makes up a number that sounds about right, or he gets a torque wrench and does the bolt up to what feels right and notes the reading.

Fresh, clean threads, clean surfaces, correct preperation , yes, torque values are very relevant.

Take bike parts which are dirty, corroded, I'll prepped, distorted, out of tolerance, torques are certainly no longer representative of applied loads.

Torque values certainly have their place on manufacturing lines and in industry, I just don't feel they're anywhere near as relevant on a bike.

Ianmunro sounds to have it spot on though.

So how often do these torque wrench users get their wrenches calibrated?

ti_pin_man

Every mechanic is taught that torque is important

Every engineer is taught that fastener/joint strain is important

EFA^^^ 😉

But no, you don't need a torque wrench for a bike generally speaking. Very few fasteners will be absolutely "torque critical" and none will be torqued to yield. Yes, you need some measure of 'feel' while you tighten any given fastener, and a general appreciation that an M4 SCH should not be tightened as much as an M8 SCH etc!

My experience of low cost torque wrenches, especially ones used to tighten bolts to low absolute torque values (<20nm) is that they are generally highly inaccurate, and how the operator holds and uses them can be critical too (especially for the "clicky" type)