CrowSeph

My torque wrench is broken, I can't set up more than 8nm.
yesterday I removed the crankset for maintenance, now i have this problem with my torque.
Can I ride safe with every bolt (chainring and crank) settled to 8nm instead of the required 12?
Sunday I have a race too, what a bad timing to lose my wrench

SoSmellyAir

If your torque wrench is broken such that you cannot set it at 12 Nm, how would you know whether the 8 Nm setting is still accurate? Better to borrow another one or to have a shop check the torque for you.

CrowSeph

Yea u right but I tested and the setting is right. I just want to know if 8nm can be problematic

choddo

I reckon 50% higher is a big chunk missing

Iride01 

You aren't likely to have a catastrophe if you torque them to the 8Nm. They very might well loosen up. They might not. If you catch it getting loose quick enough you might prevent damage. Particularly to the crank arm, if these are crank arm bolts.

However you could just go a little bit more. You'll be in unknown territory, but if you aren't ham fisted and are able to tell when the threads are about to strip or the bolt about to break, it's no big deal.

If you take it to that point where the threads start to strip or the bolt begins to stretch and break, well then you better watch out. From that point on there is no fix if it's not a bolt or nut that can be replaced easily. But still, I doubt your bike assplodes and puts you in the hospital.

However, if you are doing this stuff on the bike of some other, you probably better go get a new torque wrench if you don't feel experienced at sensing how tight it is. Especially if you are charging money for the fix.

Camilo

Why not just buy a new torque wrench locally? Auto parts stores, LBS, Home Depot, etc. etc. will have them. FWIW, I use a simple beam-type torque wrench. They're fool-proof and inexpensive.

FBinNY 

If you've been working on bikes for any length of time you should have some sense of what various torques feel like.

After all, torque wrenches don't magically produce torques, you do.

You may not be able to produce exactly 12nm based on muscle memory alone, but should be able to get much closer to it than 8nm. Especially immediately after tightening to 8. Think, tighten to 8nm, then half again more.

Or, tighten to 8nm choking down 1/3rd of the way on the handle, then move to the end and retighten to the same feel.


FWIW, this problem is a perfect example of "over reliance on technology" which is being written about in all kinds areas, from folks who get lost close to home when th we cell phone dies to pilots who can't fly anymore.

Even with my 50+ years experience, I don't claim I can match a torque wrench for b precision, but I can get close reliable, and can use feedback to sense when the numbers are leading me astray.

Bill Kapaun

If torque wasn't important, would you have started this thread?
How much can it cost you if it isn't sufficient? Don't you really want a torque wrench that works? Peace of mind.......

FBinNY 

Which brings up a question.

Which is better..... reliably close or unreliably precise?

I'm not arguing against using torque wrenches. But they shouldn't be a reason to not develop hand skills.

Failure to develop decent, though less than perfect, skills puts you in a position analogous to that of the folks who follow GPS navigation apps onto airport runways, into rivers, the wrong way down one way streets, etc.

Good tools are not a substitute for good skills.

Bill Kapaun

IF the poster was using a torque wrench on a regular basis, I'd agree. Back when I was working on cars, about the only thing I used a torque wrench on were head bolts and maybe an occasional "odd value" that wasn't in my "torque feel memory list". Now, since I haven't touched a torque wrench in a couple decades, about the only thing I'd trust is spark plugs in the old "iron" engines.
I think a bigger question is "how trustworthy is a Torque Wrench that only goes up to 8, but should go higher"?

FBinNY 

Not a bigger question, it's exactly what I meant by "unreliably precise".

Blindly trusting instruments without a frame of reference to "keep them honest" invites disaster.

Kontact 

Use a normal length L allen wrench and tighten quite firmly. Close enough.

Biker Pete 

Amazon had my torque wrench set to me overnight.

veganbikes

How did you test? I am confused how that would happen one is broken but some how you were able to confirm it was still calibrated at 8nm.

Regardless you will probably be fine and in the end you can use a properly sized quality hex wrench and tighten it up a little more as needed or I would just go to a bike shop and ask them if you are worried.

Duragrouch

Key to accurate torque is using a wrench where the setting is somewhere near the middle 80% or so of the wrench range. Most bike stuff is too low for typical 3/8" drive wrenches, unless labeled as a "microtorque wrench", common in 1/4" drive torque wrenches. Harbor Freight used to (and I think still does) have click-stop torque wrenches, 1/4", 3/8", 1/2", often on sale, any for $10 each (at least 5 years ago). (What you can do with chinese slave labor.) I matched the 1/4" one up against an old 3/8" drive micro from a quality company, torques matched (I torqued the two wrenches against each other, both clicked right on). The calibration ring came loose, but I adjusted it to just barely engage the spring when at zero, locked it down, checked again, perfect. Now Harbor Freight's adaptors, like 1/2" female to 3/8" male square, those are junk, but also due to the stress concentration of that particular one; Going the other way, 3/8" female to 1/2" male, not nearly as weak a design.

rm -rf

I got the 1/4 inch Harbor Freight 2-200 inch-pounds torque wrench for my left side Stages power meter crankarm. It uses kg-cm or inch-pounds instead of Nm on it's scale. The scale max is 200 inch-pounds = 22.5 Nm.

The crankarm instructions say 12-14 Nm, so I used 12.5 Nm = 110 inch-pounds.

It's $19 at Harbor Freight. I have a 1/4 to 3/8 adapter that stays on the torque wrench, and a set of Harbor Freight metric hex keys on 3/8 sockets. (I was using a drill-driver bits adapter, but that's harder to use, the hex key bits don't stay in the adapter very well.

I tested this torque wrench against my Park Tool beam wrench that only goes to 7 Nm, and it was quite accurate there. For an acceptable range of 12-14 Nm, the accuracy is more than enough.

I don't need to use this wrench very often, so I keep a hand written card attached to it. The card has the Stages info and a small list of Nm, kg-cm, and inch-lbs in 3 columns. From 4 Nm to 15 Nm. And a note: "store at minimum torque, not at all-the-way-open." "Maintenance: turn knob a few times to re-lube, then operate a few times at a low torque".

Hondo6

The OP is in southern Italy. He may have tool availability issues regarding reasonably-priced hand tools (e.g., from Harbor Freight et al) that we don't in the US.

We in the US often forget just how lucky we are with respect to such things.

That said: as noted above, as long as you don't go way overboard you're probably OK doing this by feel, particularly once you know what 8NM feels like.

ScottCommutes

This probably won't help because it's probably easier to just get a torque wrench, but one accurate way to measure torque without a torque wrench is to locate a "digital torque socket adapter".

This cool little gizmo fits between any socket and your socket wrench and digitally shows how hard you are pushing.

Kontact 

If we are talking about Hollowtech II pinch bolts, has anyone every seen one overtightened to where it broke anything? I sure haven't. It is two steel bolts running through a fair amount of threaded aluminum clamping down on a steel spindle. 12Nm is there largely to prevent undertightening - I wouldn't worry much about over - especially if you are using the appropriate length wrench handle.

Duragrouch

Thanks, I hadn't looked. If they have amazon, there's some deals there on 1/4" drive torque wrenches advertised for bicycle use, with several sockets and extension, $30, assuming they don't have high import taxes on such things.

Camilo

Again, OP should just check where they sell auto parts or hardware. A torque wrench is not really a special tool. Of course, I really don't know if there's any such local store where he lives, but that's my suggestion.

Duragrouch

3/8" drive torque wrenches, 150 lb-ft range, are very common. Microtorque wrenches in 1/4" or 3/8" are harder to find, at least in the past. But evidently now common on amazon, so I would hope, same in Italy.

mpetry912 

Exactly right ! what if there's an error in the web page you're using to determine the torque required for a particular fastener / applicationm ?

it HAS happened.

/markp

Crankycrank

+1. Beam torque wrenches don't go out of calibration and are less expensive. Yes, they are less convenient/slower to use with no ratcheting but if just for occasional use you buy once and won't have to worry about accuracy. To torque bolts that need a lot of turning to get to the tight point, just use a regular ratchet wrench and do the final torque with your beam wrench.

ScottCommutes

Some might argue that the beam torque wrench is actually more convenient for one or two bolts, if used as described above. No need to pre-set the torque on the wrench. Also no need to relax the spring in the wrench when storing it.