[Closed] Torque Wrench necessary?

It won't be as good a proper torque wrench, but something like this https://www.sigmasport.co.uk/app/secure/ProductDetails.aspx?FamilyID=2162 will give you some peace of mind.

Carbon frame is about the only time I would consider one for bicycle use - and you need to spend the money to get a good one.

TBH, torque is such a blunt tool for determining if the level of preload force in the bolt is appropriate (which is, after all, what the applied torque is generating and is determinant on the integrity of the joint) that there is little point getting a super accurate torque wrench UNLESS you also have the full assembly procedure to hand to include if the thread/bolt head/washers (if used) are to be dry/lubricated (what with) and the preloading sequence of the bolts, if there is more than one, etc etc etc.

If PX are quoting you a single value of torque to aim at then that's a bit naff - even Shimano (generally) give you a torque range that accounts for all of the above and you can then do you best to sit in that range with the tools you have.

it's delicate - small end of allen key

its tough - big end of allen key

I thought all joints/threads should either be greased or threadlocked (which is lubricant untill it sets) why would you ever do up a thread dry?

Not sure why you have to spend a fortune on a torque wrench for occasional use. I tested my dads one which I think he inherited and it was still within 5% or so, which is probably as accurate as you'd ever need to be, my draper one cost £20, I rebuilt my car's wheels and brakes with it and haven't died.

If you're capable of telling the difference between 4nm and 40nm and you're generally fairly mechanically competant you'll be fine without. Wrenches are useless unless they get calibrated regularly anyway.

As OP says, wrenchs for v. low torque applications are v. pricey - does your Draper go down to 4 Nm?

Yes, there are occasions when no lubrication would be used. I have seen (and had a hand in writing) the general assembly procedures for several large companies and it is illuminating the level of detail to which they will go to get uniformity in their processes..... and how easilty it can end up in court if things go wrong/the procedure isn't followed and bit start falling off!

what [i]anotherdeadhero[/i] said,

I checked the tighntess of my car wheelnuts after taking them off to check over the brakes. Aiming for 42lbft, every single one between 39 and 42.

I'd be interested in any articles (there must be one in one of the geekier magazines, practical classic, classic motorcycle mechanics etc) doing a grouptest comparing old V's new, cheep V's expensive wrenches.

There was one in MCN a few years back where they had an old set of leathers as a controll to test who made the most durable leathers in a crash situation. Conventional wisdom was that the old leathers should fall to pieces as the advice was to replace them every 5 years to be on the safe side. The rather supprising (and dissapointing for the manufacturers) was the older, cheeper leathers were tougher than their newer coputnerparts!

I'm wondering if the wisom that a £100 torque wrench calibrated yearly is so much better than a £20 one left in the cupboard isn't just a load of twaddle made up by britool?

TINAS - Not quite what you are looking for, but one procedure for a large industrial company requires that, if a torque wrench is to be used, it will be calibrated EVERY DAY and if the operator feels at any point during it's use that he's putting more force in than expected it will be recalibrated again. This will be done on a machine and then confirmed by assembly a specimen nut and bolt (the bolt has a loadcell in it and all test parts are thrown away....) For any critical application, you wouldn't even use a torque wrench - the bolt would be streched through the parts with a hydraulic jack and the nut nipped up finger tight and the jack released to guarantee the bolt force - I say again, you are trying to generate a pretension FORCE in the bolt and torque is a blunt way of doing that. You are kidding yourself in being super accurate with the torque if the rest of the assembly process isn't controlled/known.

Out in the real world - I agree - most decent wrenches won't drift by much over time. My Dad uses Snap-On kit at work and has his wrench calibrated annualy, so he has the certificate, but it's never drifted beyond it's allowable range (+/-5% IIRC)

Definitely get a torque wrench, over-tightening is bad for the components and the torques required on bike components are *very* small (you will not appreciate how small until you get a torque wrench). 🙂

I'd always use on on carbon frames, bars etc. Some are as low as 4NM, now way I'm risking it with mine or a customers bike. Worth every penny of the £140 it cost + calibration charges IMHO, but then what do I know...

Don't get me wrong - if you've got nothing else to go on but a recommended torque value then work to it. Having said that..... the bolts on, say, a stem will be designed based on their being adequate axial force in them to grip the bars. The NOMINAL torque to achieve this might be 4Nm. The TYPICAL variance on a measured torque to achieve that force is +/- 50% (and can be alot worse than that), so you might have a perfectly calibrated torque wrench, using it to the letter and hit exactly 4.000 Nm...... but the thread in the stem happed to be oversized, but in tolerance, and the thread on the bolt is undersized, but in tolerance, and whole thing is slathered in grease. So it's winding into the hole all very nicely thank you.... and at 2 Nm (which is a very small torque to start with) the design force is already achieved, but you keep turning until you get to 4 Nm....... and the bolt pulls out of the stem thread because the threads are sloppy and you've generated 50% more force in the bolt than you thought. Not your fault - you did the absolute best you could - but the mirad of variables in a seemingly simple operation have combined to leave you with a stripped thread in an expensive stem.

Hence, by all means use torque as a guide, but it's really not worth getting anal about the absolute values as there are so many other variables outside of your control. In that context, those Ritchey torque keys look like a good value way of doing it.

I can see the point with carbon and lightweight alloy stuff. But for normal bike use i have never bothered. Just don't hang on every bolt, and do them up gradually where there is more than 1

One of the points of torquing components to their correct value is to ensure that they move during a crash and not snap. Hence why stems, brake levers, gear levers will all have values that would probably be worth trying to stick to.

One anomaly, is that the torque value quoted on the side of a stem may vary with what might be required for a carbon stem to an aluminium stem.

Obviously, there are other areas where this is less vital - brake calipers, discs, derailleurs etc, where the difference between torquing above the recommended value is only likely to damage the bolts or possibly the component, but you'd have to be a real gorilla to do that much damage.

thisisnotaspoon mentions car wheels, where opinions vary quite a bit
http://www.honestjohn.co.uk/forum/post/index.htm?t=82119

But on bikes there is stuff like: Ritchey Liquid Torque "Creates extra friction between two surfaces, allowing tightening torque to be reduced
by up to 30%.
Particularly useful for use where over-clamping can damage sensitive components such as Carbon bars or steerer tubes.
Approved for use with carbon, steel, alloy and titanium surfaces.
Use with Ritchey Torqkey to ensure safe installation of Ritchey bars and stems."

Effeto " Carbogrip

Carbogrip is a special high-molecular weight silicone resin that, sprayed on a component, creates a strong grippy surface.

HIGHLIGHTS:
- prevents part slippage and the consequent overtorqueing of the fixing bolts
- facilitates clamping of smooth carbon parts
- anti-seizing
- perfect as threadlock (steel, titanium, aluminum, carbon bolts)
- waterproof
- very easy to use: no need for brushes as with other assembly pastes/liquids "

+1 for Lqd Torque/Carbogrip, or FiberGrip - all excellent.

Ritchey TorqueKey Great - only up to 5Nm so no chance of overtightening. Retails @ £12.99.

Or try Park tools torque wrenches - smaller one (part No TM1) goes up to 7Nm retailing at £50, larger one (part no TM2) goes up to 70Nm retailing at £60, neither need recalibrating.

Get in with your LBS and they may get them at a better price for you.

Most of my bolts are lubed with a proprietory "garrage toolkit muk"

its formulation is a carefully guarded secret, but it thought to be 1 part carbon, 1 part lithium grease, 1 part rust and a dash of WD40.

😀

Desk jockeys & their need to buy a torque wrench always makes me larff....

for the sake of £25 from screfix you can get one that goes down to 5nm, seems good enough to me. A desk jockey I may be but I've overtightened less stuff since I've had it