Only 6mm of thread engaged on rear skewer. Enough?

[Globalti]

It's a long story but my LBS has given me a new set of QR skewers for my Tricross disc after I found the standard ones coming loose.

I think the rear skewer is too short because when the drive side cap is tightened up and the skewer ready for camming over, only 6mm of the 11mm of available thread in the cap is engaged.

Is this enough? Whaddya think?

 

[4F]

How much is showing the other side ?

 

[simon.r]

FWIW I have a singlespeed (solid axle) with the axle thread only 1/2 way into the nut. (It's a 120mm wheel wheel bodged to fit in a 135mm frame). I keep an eye on it, but it's never moved.

Although having said that I think I'd be asking the shop for a set of QRs with a longer skewer in your position.

 

[green1]

Depends on the thread, if its M6 or smaller it's ok any larger I'd be concerned.

 

[potsy]

Mine were replaced too as I think I told you a while ago, will check it tonight.
Do you know which ones were used? Sure the lbs said they were deore that had been put on mine.

 

[mickle]

No. No no no no no no. Replace it before the thread strips.

 

[Globalti]

Thanks for the unequivocal advice Mickle!

In fact I've just phoned the LBS and they tell me they gave me a skewer for a 130mm rear when I need for 135mm. D'Oh!

 

[mickle]

Thanks for the unequivocal advice Mickle!

In fact I've just phoned the LBS and they tell me they gave me a skewer for a 130mm rear when I need for 135mm. D'Oh!

You're very welcome. Happy to reiterate if you wish.

 

[PoweredByVeg]

Yet the ISO standard for a M5 nut is 4mm thick

 

[TheDoctor]

No. No no no no no no. Replace it before the thread strips.

Don't shilly-shally about, say what you mean...

 

[Night Train]

Yet the ISO standard for a M5 nut is 4mm thick

That would be based on the nut being of a suitable tensile strength relative to the bolt, and there being a minimum of two complete threads exposed on the non load side of the nut, IIRC.

Are the skewer nuts different to the steel skewer? If so then you would want a longer thread engagement to achieve a similar pull out strength. There are also no exposed threads showing on the outside either.

 

[Globalti]

I don't know anything about formal engineering rules; all I know is that I wasn't happy with just 6mm of the 11mm of thread engaged.

 

[green1]

That would be based on the nut being of a suitable tensile strength relative to the bolt, and there being a minimum of two complete threads exposed on the non load side of the nut, IIRC.

Nope, as long as the engagement is the same as the diameter your okay. Effectively it only the first two threads that see the load.

I don't know anything about formal engineering rules; all I know is that I wasn't happy with just 6mm of the 11mm of thread engaged.

You were fine as was, at least now you have a spare. ( you did keep it didn't you?)

 

[Night Train]

Nope, as long as the engagement is the same as the diameter your okay. Effectively it only the first two threads that see the load.

It was many decades ago I learnt about the two exposed threads thing so I did a quick search and came up with these.
http://www.boltscience.com/pages/shortbolting.htm
http://www.portlandbolt.com/faqs/recommendation-on-thread-engagement

I do seem to remember something about the thread protrusion thing to counter the partially formed threads at the start of the bolt, but my MechEng degree was back in the 80's.

I wonder if it is convention or testing that supports this?

 

[Alun]

Nope, as long as the engagement is the same as the diameter your okay. Effectively it only the first two threads that see the load.
You were fine as was, at least now you have a spare. ( you did keep it didn't you?)

I dont think I'd be happy with my rear wheel held on by only 2 threads or even if the "engagement equalled the diameter" whatever the theory says. Especially if descending a long hill at 40 mph.