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Discussion Starter · #1 ·
Okay, I've got some dumb questions about chainring bolts. I tore up my fingers pretty good today...

How tight do I need to get my chainring bolts? Should I just locktight them on? I'm putting a single ring on some Sugnio cranks. I HATE the little tool for the back side, it always slips!
 

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From Parktool's torque specs, in inch-lbs

Chainring bolt- steel 70-95 Campagnolo® 84-120
Race Face&erg; 100
Truvativ® 107-124

Chainring bolt aluminum 44-88 Truvativ® 72-80

The little tool doesn't always work well with all of the bolts IME, but better than fingers...
 

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I don't like locktite for chainring bolts because itt wiil be too difficult to take them apart later since, as you well know, it's hard to hold the nut with those stupid two notch tools. .

You can use this trick to help keep the nut from spinning.

Apply a bit of medium grade lapping compound (about 80 grit, green can) to the flange area of the nut or the back of the crankarm. Be careful to only use it there and get none on the threads. When you start to tighten the bolts down the grit will bite into both the nuts and the arm and provide some traction to help keep them from spinning. (It's the same principle as using sand to get traction on ice)

You may use a bit of thin oil on the threads or assemble them dry. I use "oily" nail polish remover which gives some lubricity during assembly, and then evaporates so they stay put.

One more thing. Most of the nut tools have rounded edges and don't get a good purchase on the slot. Some are also a bit wide and don't fit into the bore of the chainring and therefore can't fully engage the slot. It's like using an old beatup rounded screwdriver to remove a tight screw.

If you have good hands use a grinder to touch up the edges of the tool making sharp square corners, and if necessary narrow it so it drops into the recess. Use a nut as a gauge for fit.
 

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leoh said:
Yes, but that didn't happen, for some reason I don't know...
Leoh- you're just lucky, don't question a good thing.

If the threads are very smooth and oiled, and the outside of the nut and the crank arm (or inner chainring) are absolutely dry, then there will often be enough friction to hold the nut from spinning. It's a question of the relative friction forces between the thread and the outside. In my experience anodized aluminum nuts are the most likely to spin, and the cheap plated brass or steel nuts least likely.

Also some track chariring bolt sets used to have knurled nuts designed to bite the crank arm to keep them from spinning, but I don't know if anyone makes these anymore.

BTW - don't bet the farm on published torque specs. They don't specify whether thay're for a lubed or dry thread (big difference) and don't allow for differences in material or thread quality. You''re better off developing "calibrated hands" and doing this by feel. Tighten them all the way home plus one more tug to be sure.
 

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I don't know how everyone else does it, but I've ever only used an Allen key or a Torx key (for FSA chainsets) to tighten or loosen chainring bolts.

The trick is to thread all the bolts on loosely by hand to locate the holes. Then use the tool to tighten opposite bolts a bit at a time (like you do with IS disc rotors).

Nearing the point where the bolts on the back will spin in your fingers on tightening from the front, simply push the bolt towards you from the back, apply sideways (or upwards or downwards) pressure on the tool whilst you are turning it to tighten.

To remove the bolts, just do the reverse: "break" (ie loosen just a bit so the bolt is not binding) the thread of each bolt with the tool, then loosen by turning the tool whilst applying sideways pressure to it.
 
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