Qu-ax with axle moving in hub

[ulph]

Hi everyone,

I read the threads in July regarding axles moving inside the hub, and in
particular the question of whether this problem had emerged on other
brands, such as the Qu-ax. This week I ordered and received a Qu-ax 20"
muni with splined hub. It looks awesome and feels awesome except that I
can feel the axle slipping inside the hub. I have of course made sure
that the cranks are really snug on the axle and also applied anti-seize
as would be appropriate.

Also the axle inside my right pedal was loose and when I opened it I
found that one of the bolts had fallen off and it was not possible to
tighten it. The threads on the axle must be damaged.

Anyhow, Fler Bollar i Luften in Sweden have been very helpful and I'm
returning the faulty parts today.

Ulf


--
ulph
------------------------------------------------------------------------
ulph's Profile: http://www.unicyclist.com/profile/7284
View this thread: http://www.unicyclist.com/thread/34369

[U-Turn]

I built a 24" MUni with Qu-AX hub and Halo SAS rim 3-4 months ago and
had it through some good testing so far, just not enough to verify it in
my eyes. So far no problems whatsoever, and the workmanship is first
order.


--
U-Turn - Member of Generation XO

Weep in the dojo... laugh on the battlefield.

'29er Tire Study' (http://u-turn.unicyclist.com/29erTireStudy/)

'Strongest Coker Wheel in the World'
(http://www.unicyclist.com/gallery/albup39)

'New York Unicycle Club' (http://www.newyorkunicycle.com)

-- Dave Stockton
------------------------------------------------------------------------
U-Turn's Profile: http://www.unicyclist.com/profile/691
View this thread: http://www.unicyclist.com/thread/34369

[jagur]

this is quickly becoming the plague of all brands.


--
jagur - #3649_all fluff i hear?

---------------------------------------------------
[image: http://gallery.unicyclist.com/albums/albup23/fc_1.jpg]

-Forget_Your_Life-

------------------------------------------------------------------------
jagur's Profile: http://www.unicyclist.com/profile/502
View this thread: http://www.unicyclist.com/thread/34369

[Sofa]

why aren't flanges just attached to the splined axle?


--
Sofa - you - pee - dee

'yea i no allot of mi frends an i r hecka smartr then othr peeple at mi
skool cus we can balense and we can ride farthar then other peeple wich
makes ur bran more exersised an it helps u consentrate an improves ur
mentel stamena' - 1wheelthrilla


'Unicycle Product Reviews' (http://tinyurl.com/368h6) *107* reviews on
*72* products

'London Unicycling Club ' (http://www.brianmackenzie.com/LUC/) (London,
Ontario, Canada)


------------------------------------------------------------------------
Sofa's Profile: http://www.unicyclist.com/profile/706
View this thread: http://www.unicyclist.com/thread/34369

[U-Turn]

Sofa wrote:
> *why aren't flanges just attached to the splined axle? *
Basic answer: The hub is made of aluminum to save weight, the axle of
steel for strength.


--
U-Turn - Member of Generation XO

Weep in the dojo... laugh on the battlefield.

'29er Tire Study' (http://u-turn.unicyclist.com/29erTireStudy/)

'Strongest Coker Wheel in the World'
(http://www.unicyclist.com/gallery/albup39)

'New York Unicycle Club' (http://www.newyorkunicycle.com)

-- Dave Stockton
------------------------------------------------------------------------
U-Turn's Profile: http://www.unicyclist.com/profile/691
View this thread: http://www.unicyclist.com/thread/34369

[john_childs]

Sofa wrote:
> *why aren't flanges just attached to the splined axle? *

That's the way the DM spline hub is made. The steel flanges are welded
to the steel axle.

The problem with pressing a steel axle in an aluminum hub is that the
manufacturing tolerances are very tight. They have to hold the
manufacturing to very tight tolerances. I'm not sure exactly how tight
the tolerances have to be, but it's in the range of just a few
thousandths of an inch. If they machine the hole in the aluminum hub
just a little bit too big then the press fit is not going to be tight
enough. If the keyway gets machined just a little too wide then the
keys will have room to move in the keyway. Getting a tight press fit
requires precision machining and careful quality control.

I'm also not sure what type of aluminum alloy they're using for the hub
body. If it's one of the softer aluminum alloys then that could be a
problem. Maybe if they went with one of the harder (and more expensive)
aluminum alloys, like something in the 7000 series like maybe 7075, then
maybe the hubs would hold up better. Maybe.

But the real problem is the need to keep very tight tolerances on the
machining for the press fit and keyway design to work. This is a
problem for the Profile design, KH design, Qu-ax design, Onza design, or
any other hub that relies on press fitting a steel axle in an aluminum
hub body.


--
john_childs - Guinness Mojo

john_childs (at) hotmail (dot) com
Gallery: '' (http://www.unicyclist.com/gallery/john_childs)
------------------------------------------------------------------------
john_childs's Profile: http://www.unicyclist.com/profile/449
View this thread: http://www.unicyclist.com/thread/34369

[Sofa]

Thanks John, but you left another question unanswered.

I have a sneaky suspiscion you know the answer...

Why don't all those brands just weld flanges to axles?

Why an alluminum hub body?


--
Sofa - you - pee - dee

'yea i no allot of mi frends an i r hecka smartr then othr peeple at mi
skool cus we can balense and we can ride farthar then other peeple wich
makes ur bran more exersised an it helps u consentrate an improves ur
mentel stamena' - 1wheelthrilla


'Unicycle Product Reviews' (http://tinyurl.com/368h6) *107* reviews on
*72* products

'London Unicycling Club ' (http://www.brianmackenzie.com/LUC/) (London,
Ontario, Canada)


------------------------------------------------------------------------
Sofa's Profile: http://www.unicyclist.com/profile/706
View this thread: http://www.unicyclist.com/thread/34369

[john_childs]

Sofa wrote:
> *Why don't all those brands just weld flanges to axles?
>
> Why an alluminum hub body? *

I don't know why one of the companies doesn't do a hub with steel
flanges welded to the axle. DM has one, but the only way to get the DM
hub is to buy a DMATU or DM Vortex.

One reason may be that they're all bicycle companies. They've already
got the aluminum hub bodies for bike hubs. They figure why not use the
same hub body for the unicycle hub. It is an easier solution for
them.

One other thing that might be influencing their thinking is that
aluminum flanges are better on the spokes than steel flanges. Aluminum
is softer and the aluminum will deform around the shoulder of the spoke
and support the spoke better. With steel flanges the steel spoke holes
can cut into the shoulder of the spoke because the steel has no give.
With steel flanges you're more likely to have a spoke break at the
shoulder. Also with steel flanges you cannot tension the spokes as
tightly because the spoke shoulders don't have as much support. So with
aluminum flanges you can build up the wheel tighter and have a stronger
wheel.


--
john_childs - Guinness Mojo

john_childs (at) hotmail (dot) com
Gallery: '' (http://www.unicyclist.com/gallery/john_childs)
------------------------------------------------------------------------
john_childs's Profile: http://www.unicyclist.com/profile/449
View this thread: http://www.unicyclist.com/thread/34369