[DaveG]

I was replacing my handlebars and stem. I have an ITM Eclypse quill stem. Using a torque wrench I start tightening the stem bolt that tightens down on the bars. WHen I get to about 100inch.lbs I am tightenening but the torque is not increasing. After a couple of turns like this I hear that frightening plink sound and the bolt has sheared off. I was certainly not overtightening and eveything was cleaned and greased. What could have caused this? Just a bad bolt?

 

[velodog]

Too tight, cross threaded, bottomed out

 

[DaveG]

not sure

Too tight, cross threaded, bottomed out

Initially I thought cross threaded but the bolt backed out pretty easily after it snapped. Nothing to bottom out on - the end is open. Maybe my torque wrench could be off (its an old Craftsman beam-style). I installed a new bolt and torqued to 130inch lbs. No problems but the initial issue in concerning. This is going to keep me up worrying at night!

 

[Nick29]

are the recommended torque specs dry or greased? Lubrication makes it quite a bit tighter at a given torque reading.

 

[DaveG]

not sure

are the recommended torque specs dry or greased? Lubrication makes it quite a bit tighter at a given torque reading.

I don't have any instructions with the stem. I have always greased the binder bolt in the past. I was going for 140 inch-lbs, based on Zinn's book

 

[OES]

I don't have any instructions with the stem. I have always greased the binder bolt in the past. I was going for 140 inch-lbs, based on Zinn's book

It's hard to imagine you wouldn't 'feel' you were overtorquing that particular bolt. That's not a bolt you'd normally put the gorilla grip to. It does sound like a materials defect to me.

 

[big_papa_nuts]

are the recommended torque specs dry or greased? Lubrication makes it quite a bit tighter at a given torque reading.

Unfortunately we that work on bikes are usually not lucky enough to get information like that. We either have to guess or "know" how particular nuts and bolts need to be treated.

If I were to venture a guess on why this particular bolt failed I would either put it on the beam style toque wench, which are basically useless in my opinion or just a material flaw. It's hard to say with out seeing it and then even then it'd be hard to pinpoint the exact cause.

 

[Visitor302]

Ya know what,, sounds like it was just a weak bolt. It happens.
Also, there's nothing wrong with beam T wrenches, as long as you pay attention.