How important is torque?
 

I've got a new bike which has a hollwtech II 105 crankset. I need to change the rings on it, but the manual is VERY specific that the two left crankarm bolts be tightened to exact specs to insure the crankarm doesn't fall off. I've exchanged older square-taper stuff within minutes, but this is definately different, since the spider arm has no bolt at all.

How important is getting the torque correct?

I don't have one but in your case with the Hollow Tech. VERY !! I pay not much attention to torque wrenches per-say, I've read here a few times concerning how critical it is, if you can't spend or don't want to spend the 50 or 100 bucks, I'd say tighten it just a bit, take it to any shop,a car shop even, let him torque it, they won't mind, I never did in my shops

Auto repair shops probably won't have the appropriate tools. Bike shop will.

Harbor Freight has torque wrenches on sale for about $20.

With the Hollowtech stuff you have to be very careful about torqueing the pinch bolts down evenly and NOT trying to close the gap all the way. Some of the cranks have a little spacer that tells you when you have them closed enough, but if that is not there you have to wing it. You do not want to crush the hollow axle and you want even torque to both sides. Buy a torque wrench and use it as much as possible.

Yeah, i agree. Auto mechanics probably would not have a torque wrench & allen sockets, let alone metric ones. :rolleyes:

The arm cannot fall off, as there is a plastic screw bolt on the end. Providing you have that spinner tool(TL-FC16) just tighten that til it enoug it is flush(arm). Then alternately tighten allens (iuse hex keys) quite snug.

Crank bolts. Vital, I'd think. In a lawsuit, improper torque can sink one's shop?

You always believe the worst of people?

Auto shops will have torque wrenches (of course), but in-lb measurements are quite rare in auto mech, and small metric allens that need socket drives nearly as rare.

Besides, an auto shop isn't set up for some some guy to walk in off the street wanting his crank tweaked. They might humor you, but they're just as likely to give you a hard time or charge a bunch.

Torque is about 8 important.

IF you have no clue what 5 N-m or 44-in-lbs feels like. Get a torque wrench. Unless you are a pro mechanic, no need to spend hundreds of dollars either. ANy torque wrench is better than no torqure wrench. Be sure to get one in the right range though. Most bicycle fasteners would use a 1/4" drive TW, which is somewhat rare, but not impossible to find.

These days, with all the carbon fiber and ultralight components, proper torque is even more important. Once you've used a TW long enough, you might get away with going by feel.

And don't paint the threads full of grease either. Those torque specs are for dry mating threads. Having any type of lubricant on the threads will alter the torque reading and will likely over torque.

If you are worried about threads seizing (aluminum is notorious for galling) or galvanic corrosion from dissimilar metals (e.g. steel bolts into aluminum), get some anti-seize compound, which are formulated specifically to prevent seizing while allowing the fasteners to be toqued properly.

Clarify this one ^. Also what significance does it play here?

Are you REALLY sure about that?

But nevertheless, i do understand the theory of your over all post. It is theoretically useless.

No more rare or harder to find than .375,.5 or .75 drive.

Yikes. So if I installed my 105 Octalinks using improper torque, should I remove them and reinstall them?