Max 5nm - do you?

[mattpayne]

5nm is surprisingly not very tight!

I've always in the past just cranked bolts up to fugging tight with no issues.
For my Carbon/ti bike I bought a little topeak 5nm torque wrench, while I understand this is less accurate than a proper TW it's a lot more accurate than my hands... It didn't stop the stem crushing a carbon steerer! Luckily having a friend in Motorsports carbon fab it was deemed salvageable...

Moral - torque wrench is a great learning tool for how strong you really are!!

 

[Tootyred]

Things only need to be as tight as required to hold them in place correctly. So, when the brake lever, bars, whatever, stops moving with the natural force of use on them.....stop tightening them.

As for carbon.....yes i always use a torque wrench, set low, then follow above......up to the max stated if really needed.

The biggest risk to carbon is burrs. Make sure what your putting together is clean and free from sharp points and edges. I've even seen new stems with ( yes you Mr Easton) with poor machining leaving a burred edge that would kill a pair of carbon bars first ride.

 

[frkl]

Torque to the spec'd value. 5nm is not much but small bolts aren't rated much more than that anyway, in terms of their normed torque rating, so its easy to over tighten.

I use a torque wrench, primarily on crank, bb, and chainring installation. Gives me peace of mind. I got a topeak twisty one with removable bits for up to 12nm for about 20 euro, and then a generic old school bar and pointer type for all the higher torque values for less than the topeak.

The advantage over the click type is that only the most expensive click type register torque on reverse threads, so aren't much use on bsa bbs. The bar type reads in both directions. Plus calibration is way easier than a click type, and i have been known to knock tools off the bench

I tested it against a calibrated click type i have for our car, and it was accurate.

Thing with torque specs on bikes--sometimes they are the norm torque rating for the bolt type, but sometimes it's about clamping force, or the strength of the threaded hole--in a steel bolt in aluminum hole, the norm rating of the bolt might pull out the threads... This is why i like seeing captive nuts on aluminum parts (eg seat post collars) rather than threads tapped directly into the alu.

 

[Chopper the ex Copper]

The temperature of the garage at the time has more affect on variance.

My Mag was about 18% out when I finally got round to having it done. The only thing I can recall that might have upset it is when I fumbled it and dropped it, and it wasn't that much of a smack.

 

[mattr]

hate it when people say "my hands are like torque wrenches", no . . . no they a re not. i think it was Park Tool who did a competition at the bike show, proving that most people massively over tightened bolts by thinking they have feel.

Might just be bike mechanics then, or useless punters.
We did the same at my work a few years ago and most of the skilled fitters were within spec just doing it by hand.
A couple of them could even tell when the (specially prepared) torque wrenches were out of spec...

They still use torque wrenches and full traceability for actual work stuff though.

 

[frkl]

The practice of marking torques on parts is relatively recent, it seems to me (recent by the standards of this forum, anyway, s0, 21st century). I always assumed it was a way to try to limit manufacturer liability.

"Oh, your handle bar slipped and you fell? Did you tighten all four bolts to precisely 4.35NM? No?"

Anyone in the industry know if that's the case?

 

[mdvineng]

For the smaller things in life that I work on.

 

[mk one]

I tighten all my bolts by hand and feel. Learnt back in the 80's/90's on bmx's, specifically the hollow stem bolts, not to overtighten. Now i work on the simple principle of tight enough to not come undone, not too tight as to strip/sheer. Never had a problem with a stuck or loose bolt in those 40 or so years. I also take into account things like brake levers being slightly looser to allow twisting in an accident instead of snapping etc

Am curious about the Park comp and its meaning on say my bolts, if they were shown to be not to spec, though my bolts have proven to be, and still do, to be sound!?

 

[MattiThundrrr]

Does that red mark on my palm from closing the qr lever count as a tension measurement?

 

[frkl]

Does that red mark on my palm from closing the qr lever count as a tension measurement?

Only if the word "closed" is legible in the redness.