Torque wrench on a carbon bike - do I really need one

sandy771

Subject says it all really !

gazeddy

imho you need one more on a carbon bike than on a alu/steel bike. it doesnt cope with being overtightened like metal does

Chunkers1980

Depends if you're ham-fisted or not.

Even then you need to be sure what both should be set for so you use the lowest common denominator

njee20

Often an over relience on them IMO - people buy a cheap torque wrench, don't have it calibrated, mistreat it etc, then develop no feel for how tight things really are - they just lean on their trusty torque wrench until it clicks, irrespective of whether that's the correct torque or not!

Giraffoto

Everyone needs a torque wrench! Get a good one, look after it, use it with care and never worry again about the tightness of your bike's bolts

sandy771

So would this be any good

http://www.chainreactioncycles.com/x-to ... -prod55950

Chunkers1980

Giraffoto wrote:

Everyone needs a torque wrench! Get a good one, look after it, use it with care and never worry again about the tightness of your bike's bolts

I don't. And don't

Giraffoto

Chunkers1980 wrote:

Giraffoto wrote:

Everyone needs a torque wrench! Get a good one, look after it, use it with care and never worry again about the tightness of your bike's bolts

I don't. And don't

You should. You really should

njee20

I disagree. They have a place, but do more harm than good for the majority of home mechanics.

coulddobetter

I don't on a carbon frame with a lot of carbon parts. I am more concerned re overtightening and stripping / damaging things. I am not saying I am a human torque wrench but nothing has broken or fallen off

njee20

Indeed, and blindly swinging on the end of a foot long torque wrench, to do a bolt which is right at the very bottom of it's range, in the faith that you can't strip things is a disaster waiting to happen!

FishFish

...but of course you can still do that with an ordinary spanner too.

cooldad

I think you miss the point.

njee20

FishFish wrote:

...but of course you can still do that with an ordinary spanner too.

As Cooldad says - you miss the point. Of course you can still do that, but a spanner won't 'tell you' when a bolt is at the correct torque, you're only going to strip things. Plenty of people just heave on a torque wrench until it 'gives', with absolutely no feel for how tight things really are. They just believe the tool they're holding.

With the sorts of torques involved in most bicycle applications, plus the fact that adding grease or friction paste or similar completely messes with the torque specs anyway, I still think there's plenty of reason not to use one.

I've never stripped a bolt and I use a lot of lightweight parts and alu bolts.

I do have a couple of the Bontrager torque keys, which are quite neat I must admit, but I'd still not put my definitive trust in them.

cycleclinic

Even when I use a torque wrench I use feel, some parts are tightened to as tight as I dare and no more, regardless of the manufactur's spec, there are a number of carbon parts that fall into that catagory and using carbon paste means lower torques are often possible and it is still secure.

Terrytibbs

Absolutely 100% yes. Why take short cuts on your precious carbon bike. There are some torque settings which are there for a reason and they should be stuck to.

Especially seat posts. Too little a torque and the seat post could slip and damage the frame depending on the design. Too tight and you could damage the carbon. As well as that you have things like 2 bolt clamps which are difficult to judge how tight you're at.

If anyone is telling you that you don't need a torque wrench for working on carbon then they're either, a) not bothered, b) Don't work in the trade and / or, c) they're bad mechanics.

Take your pic, but I would thoroughly recommend a torque wrench, even for non carbon parts. Have a look through manufacturers manuals or service instructions. They will always tell you to use a torque wrench.

You're also much more likely to not void any warranty if your bike is checked after a problem.

My only advice would be to get the right one. If you're only torquing small bolts get a wrench that goes to 15nm. If they're for bigger, higher torque bolts then get a bigger one. Don't use a big wrench that goes to 60+NM on a bolt you're doing up to 15NM.

Terrytibbs

thecycleclinic wrote:

Even when I use a torque wrench I use feel, some parts are tightened to as tight as I dare and no more, regardless of the manufactur's spec, there are a number of carbon parts that fall into that catagory and using carbon paste means lower torques are often possible and it is still secure.

I'd really recommend doing it to the manufacturers torque setting. There are zero carbon parts that meet that category you tell of. Don't pussy foot around thinking you're going to break it. Be careful not to go past it, but make sure you meet the mark otherwise there's no point at all.

njee20

So what if your stem has a torque setting that exceeds that of your bars? You're not achieving the torque on the stem, or do you risk damaging the bars? Ditto seatclamps and seatposts.

How often do you calibrate your torque wrench to put such blind faith in it?

Do you install all your bolts dry, or do you use grease? thread lock? Anti seize? What about assembly paste?

Posts like yours make you sound like a bad mechanic frankly, over reliance on a torque wrench is worse than not using one IMO. Don't pussy foot around with your maltreated torque wrench. It'll be fine, sod it, just lean a bit harder on your £400 carbon stem, the tool says it'll be fine. :roll:

Giraffoto

njee20 wrote:

How often do you calibrate your torque wrench to put such blind faith in it?

How often do you need to? Mine came calibrated (complete with a little certificate in the box) and live a distinctly mollycoddled life in their plastic cases, they don't get dropped or otherwise maltreated, so I'm guessing they can go a few years between calibrations.

The question of grease, threadlocker or other complications is not such a big deal - the same manufacturer's document that tells you the torque settings will also specify whether to put things together dry or not. Carbon assembly paste is more of a force multiplier: you use the same torque settings and get a better grip.

It's also worth pointing out that the image of someone blindly putting their faith in a torque wrench is somewhat wide of the mark. I always used to go by feel and managed thirty odd years without a stripped thread, but I don't delude myself that I can match the precision of the right measuring device. Nor would you just blindly yank away at it until it clicks, you still use your senses.

However, I accept that you don't feel the need for one, just as I accept some people prefer not to wear a helmet. It's the same deal. Your head, your choice or your bike, your choice.

njee20

It's also worth pointing out that the image of someone blindly putting their faith in a torque wrench is somewhat wide of the mark. I always used to go by feel and managed thirty odd years without a stripped thread, but I don't delude myself that I can match the precision of the right measuring device. Nor would you just blindly yank away at it until it clicks, you still use your senses.

For you, yes, well done. However I can assure you after years working in a bike shop that a lot of ham fisted people do just what I said. "I can't believe I cracked my seatpost, the seat clamp wasn't even torqued completely". Replace with stem/brake levers/bar ends as you see fit.

Of course this is more prevalent on light kit, with lower torque settings. Judging by your signature I'm guessing you don't use much of that stuff. The problem is more about bad mechanics as it is their tools!

I'm certainly not saying I'm a human torque wrench, I suspect I under torque things in a lot of circumstances, but I've never stripped anything or had bits come loose.