Does anyone use torque wrenches?

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fritz katzenjammer

Der Ubergrosserbudgie
that’s why 8nm is stamped on the clamp
6 on some, 5.1 on quite a few higher end carbon hobbies.

the last properly buggered up carbon bike through our shop had an improperly tightened seat with a 5.1 Nm spec on it. The customer was complaining of creaking and he’d messed with every adjustment that could be messed with on that bike. Our tech loosened off and then properly torqued all the adjustment points magically curing the noise
 

presta

Guru
We regularly get bikes through the shop which have been damaged because a timid home mechanic didn’t tighten something enough, leading to an assembly falling apart
Upthread I mentioned that my frame was replaced under guarantee, that was because Dawes didn't tighten the BB sufficiently when they built the bike, so after two weeks and 150m it worked loose and chewed all the threads ot of the frame.

When the time came to replace the BB I found that the LBS had glued it in with what I took to be threadlock, but it looked a bit like Isopon body filler, and as they hadn't used any grease, the threads were badly rusted. Having spent hours carefully cleaning out the compound and rust, the threads were quite badly eroded so I wasn't optimistic, but after I treated it to lashings of grease the new BB withstood full torque without stripping.

Then I had a choice: risk wearing out what was left of the threads by repeatedly removing it to inspect it, or leave it alone and hope the grease would do the job. I did the latter for ages, but then curiosity got the better of me and I removed it for no good reason. The grease hadn't dried out, but it hadn't stopped the rust either, and what came out was a load of both, it was a bit like a mixture of olive oil and breadcrumbs.

Anyhow, that was it, by the time I cleaned it up and reassembled it the thread stripped, so it's had a threadless BB in since then. I should have just left it alone until the BB wore out.
 
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CharleyFarley

CharleyFarley

Senior Member
Location
Japan
I use one regularly but never slacken off the tension when not in use. Apparently that's a bad thing? :whistle:

The instructions with my torque wrench say to slacken it after use. It also says to send it to the manufacturers every couple of years for recalibrating. I would assume that to be necessary if it's not slackened after use.
 
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CharleyFarley

CharleyFarley

Senior Member
Location
Japan
We've got one at the bike charity where I work and I've never seen it outside its box. That said we never, ever, have a carbon bike come in for service or repair. Obviously customers aren't daft and would rather take their expensive steeds to their LBS to have things done properly 😉

When I got back into cycling about seven years ago, I began to frequent a LBS, and bought three bikes from them. Although I'm not a pro mechanic I recognize botching when it's done. This LBS were professional botchers, causing a total of seven problems across the three bikes. I suspect their trainee was doing much of the work and nobody was checking it. I kept forgiving them and after the last one I had to go somewhere else, but it did get me into learning how to do my own work on my bikes. So it's nice if you have a really good LBS that you can trust.
 

Peter Salt

Bittersweet
Location
Yorkshire, UK
Do have a set of good quality torque wrenches - use them for my bikes as well as automotive repairs.

Reading through this thread, half the problems could be avoided if people just greased the threads before putting the bolts in. I do this with quite literally every bolt - even ones for the bottle cages.
 

Sallar55

Veteran
Do have a set of good quality torque wrenches - use them for my bikes as well as automotive repairs.

Reading through this thread, half the problems could be avoided if people just greased the threads before putting the bolts in. I do this with quite literally every bolt - even ones for the bottle cages.
That could open up a can of worms ,see this.

Screenshot_20230508-115707.png
 
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fritz katzenjammer

Der Ubergrosserbudgie
That could open up a can of worms ,see this.

View attachment 688771
On the other end of the scale are all the fasteners with pre-applied dry thread lock which come with modern bikes.
Did the designing engineer take the change that thread lock material will have into account when specifying the torque for that fastener in that assembly? If so, why don’t they require that the bolt be replaced after each use as the effect on the torque is greatly altered when a bolt with dry thread lock is reused.

This is the problem with being a retired process engineer... I second guess the factory all the time.

And in the above case, application of torque specifications to bolts with dry threadlock compounds pre-applied, I’d bet the factory didn’t take the effect of the thread lock product into account when setting out the torque specifications because I regularly torque these bolts to spec and end up with marginally loose assemblies.

Actually, it would be near impossible to place a specification against this type of fastener because you can’t control the amount of thread lock material applied very accurately. (Not cheaply anyway...)
 
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