Is it worth getting a torque wrench for bike repair? And if so which one?

[halloleo]

In bike part assembly manuals I sometimes read phrases like "Tighten the screw to 13nm".

I assume they mean to use a torque wrench to not over-tighten (or under-tighten the connection). Some connections are vital for safe riding, but over-tightening might damage the connection. (Once, I think, I have damaged a tread by overtightening.) Is it worth getting a torque wrench for bike repair?

And if so which one (brand? model?) is recommended? I certainly need something which can measure the torque while tightening allen screws (4-8mm) and standard hex nuts (10-15 metric).

[P!N20]

Is it worth getting a torque wrench for bike repair?

If you're dealing with carbon fibre, then yes.

If you're dealing with steel and aluminium, probably still yes, but not quite as critical.

I got a Venzo torque wrench which is on the 'budget' side of things, but has been fine for my purposes.

[blizzard]

Unless you are regularly working on your bike, a beam type wrench is probably a good buy for a few reasons:

1. They don't require calibration
2. You can see as you approach the desired torque (less risk of over torquing due to being out of calibration / failed)
3. Don't require "warm up" to be accurate (click wrenches should be clicked 10-20 times to lubricate the mechanism if they haven't recently been used)
4. Cheap


Downsides are that they are less accurate than a properly calibrated and correctly used click wrench. Can also be awkward to use, as you have to be able to see the scale on the wrench.

I have 3 beam wrenches a 2-10nm and a 10-20nm Super B. Also a 0-60nm Park Tool to pretty much cover all torque ranges, but you could probably get away with just the 2-10 and 10-20nm wrenches.

Also note, the same Super B wrench can be bought under different names for cheaper, as far as I know they are all the same.

[twizzle]

If you like shiny tools...
https://wbtools.com.au/products/torque- ... nches.html
I have a few.

And a Park deflecting beam, mostly because it can do BB cups reverse thread.

[find_bruce]

With the torque range you're after you will be looking for a 1/4" square drive & should be able to get hex bit sockets

[halloleo]

@P!N20, @blizzard and @twizzle Thank you for your comments! I guess I will look for one.

I might try the Super B beam wrench...

[Duck!]

Is it worth getting a torque wrench for bike repair?

If you're dealing with carbon fibre handlebars and/or seatposts, then yes, as those parts can be crushed and fractured if their clamps are overtightened. As far as the frame itself goes, only a band-clamp front derailleur could cause a problem with compressing and fracturing the seat tube; every other interface is supported by a component inserted to the frame

If you're dealing with steel and aluminium, probably still yes, but not quite as critical. Some aluminium alloys can be quite brittle, which can result in stripped threads if overdone, especially on higher-level parts.

Supplemental edits added in red.

[AUbicycles]

I may get shot down - but will share my thoughts on a torque wrench. Yes, a good idea and there are a few things to look our for.

Typically a smaller format (typically 2 - 15Nm) ratchet click torque wrench that tightens clockwise is all that is needed. I mention this as rarely counter clockwise is needed and some tools don't have this, For some bottom bracket there are larger formats and higher torque is needed (so for tools maybe 10 - 50Nm) but I this is really an exception and you are looking for the smaller versions.

GCN Tech recommend name brand torque wrenches such as Park Tool. Wera also have a good reputation (and good prices). You can get cheaper tools but sometimes they miss details such as accuracy (of displays) or increments (1/2, 1/3, 1/4 or 1/5 increments). One tip, see if the torque wrench has sockets.. some don't have them.

As a tip, when you are finished using the wrench, always set it back to zero. Sometimes recalibration is suggested, for home use I think this is less important than for a bike shop where it may see a lot more use and wear and tear.

[P!N20]

Supplemental edits added in red.

Approved

[Nobody]

Torque wrenches aren't very accurate when it comes to getting the bolt stretch correct. Probably in the range of 30% accuracy. That is assuming application on dry fasteners (factory coating only, not too dry from alcohol cleaned or anything). If lubricating, then according to Ajax fasteners handbook, you need to set the torque wrench for 70% of the rated torque.

As to torque wrenches. I use Warren & Brown beam type for automotive use as they should be less prone to going out of calibration than the internal spring type. Also according to the calibrating service provider I last used, torque wrenches need to be warmed up with use for 2 minutes to give a more accurate reading. I usually use a car lug nut to work the torque wrench against for 2 minutes before using it.

For bicycle use, I don't have any carbon parts and I have enough experience to know what stetch I should be getting on different fasteners these days. As in the clamps don't slip and the bolts don't break. If in doubt, use less force and see how it goes.

[skyblot]

Also according to the calibrating service provider I last used, torque wrenches need to be warmed up with use for 2 minutes to give a more accurate reading.

I would dispute this for normal use. Perhaps it is valid when calibrating to a NATA standard but otherwise I feel it is just another myth. When the torque wrench manufacturer says in thier instructions that the wrench must be warmed up for 2 minutes I'll give it some credence.

This video dispells a bunch of torque wrench myths (and they have other similar videos as well).
https://www.youtube.com/watch?v=V1Y3aB9 ... estChannel

An interesting discovery at the end of the vid is that expired shelf life Loctite significantly effects the applied torque. And that the use of anti-seize leads to significant over torque if the torque figure is not adjusted accordingly.

[WyvernRH]

Also according to the calibrating service provider I last used, torque wrenches need to be warmed up with use for 2 minutes to give a more accurate reading.

I would dispute this for normal use. Perhaps it is valid when calibrating to a NATA standard but otherwise I feel it is just another myth. When the torque wrench manufacturer says in thier instructions that the wrench must be warmed up for 2 minutes I'll give it some credence.

Yes, sorry I don't believe this one either. Possibly for your own peace of mind you might want to test a wrench against a known torque, but I can see no reason in engineering or physics that a steel torque wrench would need 'warming up'.

Richard

[OnTrackZeD]

Also according to the calibrating service provider I last used, torque wrenches need to be warmed up with use for 2 minutes to give a more accurate reading.

I would dispute this for normal use. Perhaps it is valid when calibrating to a NATA standard but otherwise I feel it is just another myth. When the torque wrench manufacturer says in thier instructions that the wrench must be warmed up for 2 minutes I'll give it some credence.

Yes, sorry I don't believe this one either. Possibly for your own peace of mind you might want to test a wrench against a known torque, but I can see no reason in engineering or physics that a steel torque wrench would need 'warming up'.

Richard

Well the instructions for my Torque Wrench state's to warm it up by clicking it ten times.

[find_bruce]

I can see no reason in engineering or physics that a steel torque wrench would need 'warming up'.

You could be warming up the grease not the steel

[Nobody]

I'll just add a subjective observatinn that I once heard and found to be true. Some metals appear to relax after a short time once under tension.

Do up a bolt to what you think the tension should be. Wait for five minutes. Come back and wrench it again and you may find after everthing has settled that you may be able to put up to another quarter of a turn into the bolt before it has the same turning resistance as it had initially. You may not see it on all bolts, especially bigger ones like wheel studs etc. But it's something I have noticed and used to my advantage by going over bolts a second time before use.

Like many on here, I come here to learn and give where I can. So I'm only passing on what I've heard/seen/read/watched from what experts have apparently conveyed to me over the decades. I would trust that a person that calibrates torque wrenches for a living would have tested enough to know what he is talking about. If it is wrong, I apologise for leading everyone astray. Subjective as it is, I've noticed the Warren & Brown torque wrench gets slightly more flexible after after 2 minutes of hard work compared to when I initially tried it. It appears to click off at the same setting slightly more easily. Having said that, like I said earlier, even the best, most calibrated and well used torque wrenches are only 30% accurate translating to actual bolt stretch. So it's no big deal really.

[skyblot]

Having said that, like I said earlier, even the best, most calibrated and well used torque wrenches are only 30% accurate translating to actual bolt stretch. So it's no big deal really.

I was coming back to say exactly the same! And that how the torque wrench is used has a much greater effect on the applied torque than any supposed benefit of "warming up" a torque wrench.

I've spent over 40 years turning spanners in aviation, torque wrenches are simply a way of life and a major aid in maintaining consistency, though sometimes this is taken to extremes.

Many years ago at a small maintenance facility, we were queried about torque wrench calibration. (This was long before electronic torque checkers etc.) We showed a simple balance beam arrangement with calibrated weights. The inspector didn't like it, but the maths were irrefutable and we passed the inspection.

Fast forward to the recent past and as a result of the approvals and audit programmes the company decided that each use of a torque wrench must be recorded in the paperwork against the item it was used on (and then recorded in a database). This was deemed cheaper than providing torque testers throughout the workshops. At the time I asked what we were going to do if a torque wrench failed annual calibration, recall every job for the past year? Of course it happened, and the Quality and Management teams sat across the table from each other in silence.

Bottom line for the OP: yes, buy a torque wrench or two. A 1/4" drive covering 3-20 Nm, and a 3/8" drive going up to 50Nm will do 99% of bike work (the smaller one would be the priority in my book). Buy from reputable tool supplier and you can be confident it will work fine, but be aware that most of the lower priced ones only torque in one direction even though they might have a ratcheting head. I bought a 150 ftlb one from Total Tools and I'm pretty impressed with it.

More important is how precisely the wrench can be set. I have 2 torquewrenches that are useless, simply because they can't be set precisely; on one the graduations are too coarse, the other has an optical window and the number set can change by about 5Nm depending on how you look at it!

[Andy01]

I might suggest that the "instruction" to warm up the wrench by clicking several times may be a means to providing a "reset" on the wrench for wombats who have left it stored for a period under tension (ie. still set to a specific torque torque setting). There is nothing to warm up.

I would also suggest that bolt stretch is not a "thing" at the vast majority of low torque applications used on a bicycle. Even if the bolts are small, they are unlikely to stretch at around 8-10Nm.

Bolt stretch certainly is a thing in large industrial applications where hundreds or thousands of Nm are applied. For the really big stuff (I am talking about bolts with a diameter of over 4" / 100mm, bolt diameter, not nut size), the best way of "torquing" is to hydraulically stretch the bolt, and spin the nut up finger tight and then release the hydraulics.

[blizzard]

My last torque wrench had instructions to click the head 10 - 20 times to warm-up. I believe it's more about getting consistent friction between the slip surfaces in the spring mechanism. I can't see that it hurts to do it.

I can see how any warm up is required for a beam wrench.

Torque on bolts depends on the bolt prep i.e. dry, grease, oil. Lubrication will decrease the required torque for same clamping force. Unfortunately, the bike industry is very poor at specifying torque, often the torque printed on the component is max torque but not always, also they don't specify the bolt prep assumed for their torque specs.

In terms of torquing and then double checking, it's very common to torque bolts and then retorque after a set time as mating surfaces bed in etc.

[warthog1]

Been a good read. I've learned a bit about torque wrenches.

[uart]

Well the instructions for my Torque Wrench state's to warm it up by clicking it ten times.

I think that "warm up" is a misnomer. I've always been told that it's to make sure that the pivot-clicker is properly lubricated. It's not necessarily the case that the pivot-clicker is always going to be dry (and therefore a bit tighter than it should be) if the wrench hasn't been used for a while, but clicking it a few times (on a medium torque setting) is just to make sure.

[WyvernRH]

Well the instructions for my Torque Wrench state's to warm it up by clicking it ten times.

I think that "warm up" is a misnomer. I've always been told that it's to make sure that the pivot-clicker is properly lubricated. It's not necessarily the case that the pivot-clicker is always going to be dry (and therefore a bit tighter than it should be) if the wrench hasn't been used for a while, but clicking it a few times (on a medium torque setting) is just to make sure.

Hmm, Ok if that's what it says...maybe clickers need to have the lube loosened up?
However, I hunted up the instruction leaflets for my set of SidiChrome deflecting beam torque wrenches and no mention of warming up, just stuff about taking care of the wrench and proper lubrication. This is from 35-odd years ago when I could claim them as a tax deduction mind you, so maybe the world has gone ahead. They are also overkill for most if not all hobby bicycle applications IMHO. No idea what the three wrenches would cost now but I'm guessing around the $1000?

I do also own a Park beam wrench (about $90 IIRC) for the 0-20 small stuff on a bike which really covers 99% of what needs to be torqued up on a bicycle for ease of use and accuracy. Most bolts on a bicycle are quite small diameter and not torqued up to the extent you have to worry about windup - and really, near enough is good enough for this sort of application. Mostly you are trying not to over-torque an item IMHO, it does not have to be dead-on.

Richard

[halloleo]

Unless you are regularly working on your bike, a beam type wrench is probably a good buy.

Hi @blizzard, had a look for torque wrenches and I think the Super B Beam wrench is appropriate for me. However in a bike shop somebody told me, that these type of torque wrenches don't stay well calibrated. What is your experience?

Happy cycling,
Leo

[blizzard]

There is nothing really to calibrate, it uses the deflection of the lever to measure torque which dependent on the cross section of the lever and stiffness of the material. As long as the scale is at 0 when not in use it should be ok. (The Park Tool beam wrench instructions actually tells you to bend the indicator back to 0 of its not on zero for "calibration")

They are generally less precise than properly calibrated click wrench, but should be close enough for most bike applications.

[halloleo]

Thanks! Makes sense.

[g-boaf]

I have one like this:

https://www.ebay.com/itm/323923881827

It has also been useful for other things like doing work on my computers where certain things have to be tightened to particular Nm values. Just very useful for many things.