Servicing Wheel Bearings

[JonBuoy]

Your 130mm hubbed wheel would fall out of the 135mm dropouts, given the chance.
How can the central part of the axle be in tension yet sufficient friction be exerted to stop that? Friction from the outside of each dropout (by the axle nuts) is not enough to secure the wheel. Friction from the inside (the cone lock nut) is needed for security.
Think about that, while you try to get to sleep tonight, 'as a thought experiment'.

Assuming I have the terminology correct - the right hand dropout is nipped up between the right hand locknut and the right hand axle nut in the same way that the left hand side is. There is plenty of friction without any tension in the central portion of the axle. Remove the hub, rim, spokes etc in your thought experiment and just leave the axle behind now saw through the centre of the axle and the dropouts will spring back to 135mm spacing - showing that the axle was under (a tiny bit of) tension. If you had a QR and could somehow just saw through the hollow axle this wouldn't happen as the axle is under compression from the QR.

 

[CharleyFarley]

I agree that tightening a QR will compress the axle and reduce the clearance in the bearings but I'm not convinced about the bit that I have emboldened. Surely tightening up the nut on the end of the axle puts the dropout into compression and the (very short) bit of the axle passing through the dropout into tension. There are also frictional and torsional things going on that I will conveniently ignore. You do this to both axle nuts independently but that has no effect on the length of axle between the dropouts and hence no effect on the clearance in the bearings. Or have I misunderstood something?

That sounds like an excellent hypothesis, one that I can easily go along with.

 

[CharleyFarley]

I'm thoroughly confused with all the technical talk, so all I can say is (using my fat bike for example) I've done about 4,000 miles between bearings servicing, and I've had no problems with it. It appears I must have done something right.

 

[Ajax Bay]

Assuming I have the terminology correct - the right hand dropout is nipped up between the right hand locknut and the right hand axle nut in the same way that the left hand side is. There is plenty of friction without any tension in the central portion of the axle. Remove the hub, rim, spokes etc in your thought experiment and just leave the axle behind now saw through the centre of the axle and the dropouts will spring back to 135mm spacing - showing that the axle was under (a tiny bit of) tension. If you had a QR and could somehow just saw through the hollow axle this wouldn't happen as the axle is under compression from the QR.

Hope you slept well
"the right hand dropout is nipped up between the right hand locknut and the right hand axle nut in the same way that the left hand side is. There is plenty of friction without any tension(1) in the central portion of the axle. Remove the hub, rim, spokes etc in your thought experiment and just leave the axle behind [with its two locknuts] now saw through the centre of the axle and the dropouts will spring back to 135mm spacing - showing that the axle was under (a tiny bit of) tension(2)."
Which of the emboldened statements is true? If there's tension in the "central part of the axle" there is a dearth of friction (between the locknut and the inner side of the dropout).

This nutted axle has locknuts the outside faces of which are 130mm apart.
The axle nuts are tightened (let's say equally) against the outside of the dropouts until the 135mm spacing of the frame has compressed to 130mm OLD. The axle is in serious tension (let's hope this is a steel frame btw): the frame stiffness is generating that tension.
The forces on the locknut are equal: it has the same tension pulling (applying force inwards to) the centre as it has from the axle nut/dropout interface pulling outwards.
Therefore there is no additional force between the inside of the dropout and the locknut (applies to both left and right).
Thus there is no force to generate friction between the locknut and the inside of the dropout.
In order to to fasten the hub securely in the frame, the axle nuts need to be tightened further, first to overcome the tension and then to create sufficient 'nipping up' force between the inside of the dropout and the locknut (applies to both left and right).
And that then means the main central axle is in compression.
QED and HTH

 

[JonBuoy]

Hope you slept well
"the right hand dropout is nipped up between the right hand locknut and the right hand axle nut in the same way that the left hand side is. There is plenty of friction without any tension(1) in the central portion of the axle. Remove the hub, rim, spokes etc in your thought experiment and just leave the axle behind [with its two locknuts] now saw through the centre of the axle and the dropouts will spring back to 135mm spacing - showing that the axle was under (a tiny bit of) tension(2)."
Which of the emboldened statements is true? If there's tension in the "central part of the axle" there is a dearth of friction (between the locknut and the inner side of the dropout).

This nutted axle has locknuts the outside faces of which are 130mm apart.
The axle nuts are tightened (let's say equally) against the outside of the dropouts until the 135mm spacing of the frame has compressed to 130mm OLD. The axle is in serious tension (let's hope this is a steel frame btw): the frame stiffness is generating that tension.
The forces on the locknut are equal: it has the same tension pulling (applying force inwards to) the centre as it has from the axle nut/dropout interface pulling outwards.
Therefore there is no additional force between the inside of the dropout and the locknut (applies to both left and right).
Thus there is no force to generate friction between the locknut and the inside of the dropout.
In order to to fasten the hub securely in the frame, the axle nuts need to be tightened further, first to overcome the tension and then to create sufficient 'nipping up' force between the inside of the dropout and the locknut (applies to both left and right).
And that then means the main central axle is in compression.
QED and HTH

Apologies - I should have said: 'There is plenty of friction without any tension or compression in the central portion of the axle.'

Did you actually try sawing through the nutted axle to see whether it was in tension or compression?

NB I recommend doing this as a thought experiment but feel free to trash an axle if that helps your understanding.

 

[Ajax Bay]

Apologies - I should have said: 'There is plenty of friction without any tension or compression in the central portion of the axle.'
Did you actually try sawing through the nutted axle to see whether it was in tension or compression?
NB I recommend doing this as a thought experiment but feel free to trash an axle if that helps your understanding.

'There is plenty of friction without any tension or compression in the central portion of the axle.'
Sorry: If there's "no compression" in the central (130mm) section of the axle then there's zero pressure/force on the inside of the dropouts (and the wheel will drop out, given the slightest chance).
"Did you actually try sawing through the nutted axle to see whether it was in tension or compression?"
Certainly did . With the nuts as described when I tried to hacksaw through, the axle just fell out of the dropouts in the first few cut strokes. Perhaps I should have turned the frame upside down. When I tightened up the axle nuts so the axle was held securely in the dropouts (which is, remember what the axle nuts are for), I got half way through (really hard going) and then the compression in the axle nipped the blade and could cut no more. I eased off the axle nuts and, with the compression gone, I got the blade out.
This result didn't really "help my understanding", it confirmed it. Hope you too can benefit.
Rather than using a 130mm OLD axle in a 135mm frame, I used an old 126mm OLD axle in a 130mm OLD frame.