Got NR/SR cranks and a torque wrench?
 

I am certain that there had to have been torque specs for NR cranks but I’ve never seen them.
And while I’ve installed plenty of said cranks, It’s been years since I did my last set and my upper body strength and muscle memory have faded.
So here’s the deal: are you riding NR or SR cranks now? Do you have a torque wrench( here’s looking at you AdventureManCO )?
If so, could you apply said wrench to said cranks and see what they are torqued to?
Otherwise, I’m destined to ride around with a peanut butter wrench in my pocket till things get settled.
Thanks

Never used a torque wrench on those and not that sure I have a socket that will fit to use my torque wrench. The crank bolt doesn’t even need to be *that* tight, not even really needing an “oomph” when you cinch it down, as opposed to an Italian thread drive side BB cup which requires an “oomph!!” - two exclamations.

I usually do it by feel: When something snaps off, I feel that I’ve gone too far.

Yes. Just a check on an bolt that is currently on a crank that is in use. Start with a low torque, then increase it in say five ft lbs steps until it doesn’t click. Or if you have a wrench with an indicator, no need to take it in steps

That's a sort of misunderstanding of how tapered spindle cranks work. The torque measured on the torque wrench isn't tension, but a measure of the work to get the crank seated firmly on the spindle. Once the crank is seated, the bolt just keeps the crank from moving and it does that at a lower tension. The bolt should be snug, but not at mounting torque. If you apply full torque to it again, you will move the crank a little bit further onto the spindle.

Yes. Just a check on an bolt that is currently on a crank that is in use. Start with a low torque, then increase it in say five ft lbs steps until it doesn’t click. Or if you have a wrench with an indicator, no need to take it in steps

Torque settings are a guide.
There is enough variability in manufacturing tolerances alone to justify this, nevermind the possible intermixing of different manufacturer's parts and the effect of repeated fasten/unfasten cycles.

With experience[1], you can detect the change in effort required to get a threaded fastener to rotate.
For tapered cotterless cranks, there is more than one such change.
With a clean lubed crank the first stage just takes up initial clearances
The second stage is when the screw or nut forces the crank onto the taper; this steadily increases (due to the taper).
The third stage is when the crank resists being stretched by the taper enough that further rotation of the screw/nut starts to stretch that in preference to the crank.
This stage has a sharp increase in effort required.
The fourth stage requires continued higher effort, ending with either the threaded part breaking or the crank splitting.
Stop after the third stage.

[1] Studies have shown that the inexperienced tend to overtighten fasteners under some small-ish size, under 1/4" as I recall.
If you think that might be you, drill a few holes in something and put some screws and nuts in them and tighten them until they DO break - then you'll know what it feels like.

Campy recommends 28 Ft-lbs. / 38N.m on their 9 - 10 speed square taper alloy crank arms. I don't know if that is a good for NR/SR.

The Park Tool chart that I printed a while back says 312-324 inch-pounds for Campy square taper cranks. That equates to 26-27 foot-pounds. The specs for other brands are about the same, but my torque wrench only goes to 250 inch-pounds so that's the number I use.

ok, that puts it below the Shimano spec for cranks, 305-391 inch lbs, and the range is smaller, both of which I expected from past experience. Plus you’ve given me a figure that you’ve used in the real world so your number obviously works. Thanks. That’s what I needed.

Good one 🤣🤣

Why push the crank on further by doing this?

​​​​​​​If you carefully go through his scenario, the nut will never move. The last movement will be the torque wrench moving, and therefore "clicking". The fastener does not move when the torque wrench clicks.

Torque the bolt with the Campy tool. You will definitely not make it too tight.

https://cimg1.ibsrv.net/gimg/bikefor...7b457e1da5.jpg

Yeah, I’ve had one of those for decades. Never had an issue with the crank being too tight when I’ve used it. However, loose cranks are another story. Hence the torque wrench. That and a desire to have a measurable, reproducible results that don’t lead me to second guess my work.

Maybe add a short piece of PVC for a minor cheater, make a couple different lengths to graduate the torque up as you lean in?

I would expect that the the stretch and or wear? of the tapers in the crank arm may effect it some as we see some that bottom out and may not be tight enough, maybe? :foo:

And FWIW, I have shimmed the spindle and used washers that allow the spindle to protrude into them on stretched cranks. :twitchy:

Never ground the end of the spindle, yet but have always been able to find a spare with a tighter fit. ;)

Is that when you stuff a ball of duct tape in the hole?

That's only for pedals.

If the bolt is at torque. But as I already carefully explained, it probably will not be. So the bolt will turn however far it needs to for torque to get to the wrench setting, at which point you have moved the crank arm inboard by the number of threads times the number of rotations of the bolt.

If you keep retightening your crank with the same torque setting, you should second guess what you are doing.

I grease the tapers and the bolt threads/washer and use the Campy tool uncheated. Been doing that since about 1978. Never had any come loose.

Works fine for me.

So the best scenario is that the bolt is already properly torqued, and the worst case disaster is that the bolt becomes properly torqued.

thanks for the lecture.

Ever seen a deformed arm taper from retightening the bolt? Last year on flips, I saw three. They were all from the same owner that probably didn't have a clue aluminum could deform on steel. One was so bad on a drive-side Zeus that the inner chainring could only be used with the biggest two rear cogs, else the chain rubbed on the big chainring. The arm was toast, which was really unfortunate with such a rare component.

I wouldn't have any problem with someone removing the arm first before remounting it with a torque wrench.

I think it's also important that if you describe the amount of torque used for your particular crankset, you also mention whether or not grease was used and how much.

Yep me too, I'm a greaser who has never owned a torque wrench. I use a ratchet wrench most often but it's the same length as a peanutbutter, just a bit more comfy on the hand so I might get them a bit tighter than most people would with a PB wrench. I don't re-tighten them after riding, it's set-and-forget until the next servicing. My cranks stay on and don't split or get wallowed out. When I was racing I trained and raced in all weather, so my NR BB bearings got repacked on the regular, lots of removal/re-installs, so if I was doing damage to my cranks, I would have noticed it. Oh and I probably did my first in about 1971, a tad more years than Steel Charlie . Some of those years I was a paid wrench at a LBS.

I'm not trying to get anyone else to do it my way, I just know what works for me.

Yes, many times.

Have you ever seen a deformed arm taper from correctly torqueing the bolt?