How much thread on the axle?



D

Daveb

Guest
I've just been doing some work on my rear wheel and noticed
how little of the axle is being used to support the frame.
It looks to me that the weight of the bike may even be being
supported by the quick release screw. Anyway, I'm hoping
someone can let me know if this is normal or a recipe for
disaster. Seeing I'm only just recovering from a headstem
stuff up, I think I might get banned from cycling if another
mechanical failure occurs. I dropped some pics onto the
following url to show what I mean.

http://members.optusnet.com.au/~dbuerckner/bikestuff/axle.h-
tm

Dave B.
 
"DaveB" <[email protected]> wrote in message
news:[email protected]...
> I've just been doing some work on my rear wheel and
> noticed how little of the axle is being used to support
> the frame. It looks to me that the weight of the bike
> may even be being supported by the quick release screw.
> Anyway, I'm hoping someone can let me know if this is
> normal or a recipe for disaster. Seeing I'm only just
> recovering from a headstem stuff up, I think I might get
> banned from cycling if another mechanical failure
> occurs. I dropped some pics onto the following url to
> show what I mean.
>
> http://members.optusnet.com.au/~dbuerckner/bikestuff/-
> axle.htm

After checking your pics I would suggest that you need to
recentre your axle in the cones/nuts. It is too far over to
the LH side.

Back off the LH nut and cone several turns, then tighten the
RH cone to readjust the bearing and lock in place. This
should give you about 4mm of axle protruding on each side.
At present you have about 2mm on the right and 6mm on the
left. With the axle centred you'll have no problems.

Cheers Peter
 
Peter Signorini wrote:
> "DaveB" <[email protected]> wrote in
> message news:[email protected]...
>
>>I've just been doing some work on my rear wheel and
>>noticed how little of the axle is being used to support
>>the frame. It looks to me that the weight of the bike
>>may even be being supported by the quick release screw.
>>Anyway, I'm hoping someone can let me know if this is
>>normal or a recipe for disaster. Seeing I'm only just
>>recovering from a headstem stuff up, I think I might get
>>banned from cycling if another mechanical failure
>>occurs. I dropped some pics onto the following url to
>>show what I mean.
>>
>>http://members.optusnet.com.au/~dbuerckner/bikestuff/-
>>axle.htm
>
>
> After checking your pics I would suggest that you need to
> recentre your axle in the cones/nuts. It is too far over
> to the LH side.
>
> Back off the LH nut and cone several turns, then tighten
> the RH cone to readjust the bearing and lock in place.
> This should give you about 4mm of axle protruding on each
> side. At present you have about 2mm on the right and 6mm
> on the left. With the axle centred you'll have no
> problems.
>
> Cheers Peter
>
>

Even then though I'll still only have about 4mm at either
end, so I'm wondering if that is normal. Is that what the
frame is supported by? My MTB (which is certainly getting on
in years) doesn't have quick release so obviously the axle
goes well out either side of teh frame for the lock nuts,
and when I look at the MTB compared to the road bike
something just doesn't look right.

Dave B
 
DaveB:

> Even then though I'll still only have about 4mm at either
> end, so I'm wondering if that is normal. Is that what the
> frame is supported by? My MTB (which is certainly getting
> on in years) doesn't have quick release so obviously the
> axle goes well out either side of teh frame for the lock
> nuts, and when I look at the MTB compared to the road bike
> something just doesn't look right.

4-5mm of thread contact with dropouts is typical for both
MTBs and road bikes. There hasn't been any significant
problems because of this. The only concern is if you have
ultra-thick dropouts and your skewer rod then becomes too
short; I think this is a non-issue though.
 
"DaveB" <[email protected]> wrote in
message
news:[email protected]... <SNIP>
> then though I'll still only have about 4mm at either end,
> so I'm wondering if that is normal. Is that what the frame
> is supported by? My MTB (which is certainly getting on in
> years) doesn't have quick release so obviously the axle
> goes well out either side of teh frame for the lock nuts,
> and when I look at the MTB compared to the road bike
> something just doesn't look right.
>
> Dave B
>

It's the friction which keeps your axle in place, by
pressing the lug against the retaining bolt. You would ruin
the thread if you would put all the weight directly on the
axle. Just look at the lug of a road bike, the axle is often
not positioned at the back of the lug opening, but somewhere
in the middle and has to be kept there by pressing the nut
against the lug. Also when you have an axle which protudes
on both sides and is attached with locking nuts, the forces
are transmitted metal to metal, via the friction.

Joop
 
Joop:

>
> "DaveB" <[email protected]> wrote in
> message
> news:[email protected]... <SNIP>
> > then though I'll still only have about 4mm at either
> > end, so I'm wondering if that is normal. Is that what
> > the frame is supported by? My MTB (which is certainly
> > getting on in years) doesn't have quick release so
> > obviously the axle goes well out either side of teh
> > frame for the lock nuts, and when I look at the MTB
> > compared to the road bike something just doesn't look
> > right.
> >
> > Dave B
> >
>
> It's the friction which keeps your axle in place, by
> pressing the lug against the retaining bolt. You would
> ruin the thread if you would put all the weight directly
> on the axle.

No, the rider's weight is taken up by the axle threads in
contact with the dropouts. Look at your dropouts and you'll
see scoring where the axle threads make contact.

> Just look at the lug of a road bike,

Lug?

> the axle is often not positioned at the back of the lug
> opening, but somewhere in the middle and has to be kept
> there by pressing the nut against the lug. Also when you
> have an axle which protudes on both sides and is attached
> with locking nuts, the forces are transmitted metal to
> metal, via the friction.

The axle takes up the weight of the rider, not the nuts
nor QR knobs. These mainly keep the hub from going out of
the dropouts.
 
Replacement rear axles are typically 11mm longer than the
OLN dimension (eg 141mm for 130mm OLN, 146mm for 135mm OLN),
which means 5.5mm at each end. I've added a 2mm spacer each
side to use a 130mm hub in a 135mm frame, bringing it down
to 3.5mm each side and had no problems, so I would say
anything over 3mm or so is fine.

Nick

DaveB wrote:
>
> Even then though I'll still only have about 4mm at either
> end, so I'm wondering if that is normal. Is that what the
> frame is supported by? My MTB (which is certainly getting
> on in years) doesn't have quick release so obviously the
> axle goes well out either side of teh frame for the lock
> nuts, and when I look at the MTB compared to the road bike
> something just doesn't look right.
>
> Dave B
 
"Jose Rizal" <_@_._> wrote in message
news:[email protected]...
> Joop:
>
>
<SNIP>
> No, the rider's weight is taken up by the axle threads in
> contact with the dropouts. Look at your dropouts and
> you'll see scoring where the axle threads make contact.
>

The friction forces are very strong. If I position the front
wheel a bit down from the stops and I put my full weight on
it, the axle does not slip. So it can take 90+ kg on one
wheel with friction only. Also I often have one side of the
front axle to the stop and the other is a bit off for
propoer positioning: and it stays there (no shifting).

The scoring marks can be there as there always a slight
movement possible but I think they are mainly from when the
wheel is put in. If it would only rest on the threads, they
will be crushed with all shock forces from the bumps on the
road. As a kid I often failed to tigthen the bolts properly
and I often had an axle where I could not get the bolts off:
the threads were completely squashed.

>
> > the axle is often not positioned at the back of the lug
> > opening, but somewhere in the middle and has to be kept
> > there by pressing the nut against the lug. Also when you
> > have an axle which protudes on both sides and is
> > attached
with
> > locking nuts, the forces are transmitted metal to metal,
> > via the
friction.
>
> The axle takes up the weight of the rider, not the nuts
> nor QR knobs. These mainly keep the hub from going out of
> the dropouts.
>

I think it is the other way around: firstly the forces are
distributed via friction, the axle-dropout contact is a
second line of defence.

Joop
 
On Wed, 31 Mar 2004 02:01:53 GMT, Jose Rizal <_@_._> wrote:

>No, the rider's weight is taken up by the axle threads in
>contact with the dropouts. Look at your dropouts and you'll
>see scoring where the axle threads make contact.

That may be the norm but it isn't necessarily so I had a
bike which had a slight mishap and if the axle was put in
the correct place in the dropouts the wheel didn't run true.
It had to be out of position on one side but it ran like
this for years without the axle touching the dropouts on one
side and relying on the friction of the QR dobbie to hold it
in place - The QR was no tighter than normal
 

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