The other day, I rebuilt a rear wheel that was originally laced with a Neumen hub using a
DT hub instead (→here).
I want to explain what was wrong with the Neumen hub.
That wheel was originally built by an amateur who had the offset rim orientation reversed left and right,
so I corrected that while changing spoke gauges and relacing everything.
That was on May 23rd,
but afterward, when I tightened the thru-axle properly
(not over-tightened, but within the correct range)
the rear wheel would seize up like a fixed gear,
so in October I completely replaced the hub bearings.
After that, when I tightened the thru-axle normally again,
the rear wheel froze up once more,
and knowing it was dangerous but having no choice that day,
I loosened the thru-axle slightly and
rode home with play in the rear wheel from side to side.
The images below are from October when I replaced the bearings.
↑This is the bearing on the left side of the hub body,
and it's already been replaced here.
The bearing that was completely destroyed was the one on the freewheel body,
but the hub body bearing was also damaged
and the hub axle was wobbling slightly off-center,
so I replaced all the bearings.
I threaded the hub axle through from the right side of the hub body.
Since there are no threads cut,
the left end is a press-fit,
but it's not a simple fit tolerance—
it's a press fit relationship.
↑This is the left end viewed from the inside,
and this is press-fit all the way onto the hub axle.
The outside of the left end has threads cut for the
bearing cone adjustment nut,
and this piece alone must not be press-fit onto the hub axle, but
I did it anyway for explanatory purposes.
From this state, you cannot remove the left end by hand.
Even when the left end is fully press-fit all the way,
there's still a gap between the end and the bearing,
and in this state the hub axle can slide left and right.
The image above shows it shifted all the way to the left.
The bearing cone adjustment nut.
I installed the bearing cone adjustment nut on the left end.
The left end with the bearing cone adjustment nut
viewed from the inside.
The higher step contacts only the bearing inner race,
but since the hub bearing was damaged with off-center play,
other areas have also worn.
I turn the bearing cone adjustment nut toward the hub body
and tighten it at the point where there's just slight pressure
on the bearing inner race.
Since the left end is a very tight press-fit,
the force of pressing the bearing with the adjustment nut alone
won't pull it out of the hub axle.
Also, this bearing cone adjustment nut applies
quite a bit of force to the inner race, and since there's no place to fit a hub wrench,
you can only turn it by hand—but if you tighten it firmly,
even with brand new bearings you can make
the hub rotation quite heavy.
There seems to be one more reason for this (explained later).
↑This is the freewheel body before bearing replacement.
The seal on the outer bearing is already lifting,
and when I removed it, a cracked retainer ring came out too.
The bearing balls are heavily damaged.
I removed the front and rear bearings and
cleaned the freewheel body.
The ratchet mechanism on this hub is
the same design as the DT star ratchetknockoff,
so it works by fitting the pawl ratchet components onto a spline-like surface
that's basically a square wave rounded into arcs.
On most freewheel bodies, both the front and rear bearings
are press-fit from outside the freewheel,
but on this freewheel body, the rear bearing
is press-fit from inside.
The Lief hub freewheel body that we stock for nomLab wheels
also uses the rear bearing press-fit from inside,
so it's not completely unique.
I replaced the bearings by sandwiching them
from both sides of the freewheel body.
Yellow-sealed bearings are rare,
but these are made by DT.
Now, as you might notice,
this freewheel body has no spacer inside
that contacts both bearing inner races.
I didn't forget to install it—it wasn't there from the start.
There's just no way this could withstand
normal thru-axle clamping force in any reasonable sense.
The significant heaviness that occurs from a certain point onward
when tightening the bearing cone adjustment nut
is probably partly due to this too.
I don't see how this kind of cheap, petty weight-savings benefit
outweighs the detriment of severely shortening hub lifespan.
Another manufacturer doing the same thing is
Tactic Racing's freewheel body (→here).
Another fairly significant factor to consider
is that the freewheel body is for SRAM XDR.
Because the freewheel body diameter is small,
you can't fit bearings with large outer races.
So the size difference between inner and outer races is small,
which means the balls inside are also smaller,
making them weaker under compression.
It's possible that if it were a quick-release rather than a thru-axle,
and a Shimano freewheel body, the problems would have barely occurred,
which might be why they don't include an inner race spacer
in the freewheel body.
Here are some manufacturer images:
↑This is an image of a
SRAM XD freewheel body for Neumen,
but currently there's a Gen 2 (Generation 2)
freewheel body that's separate from this.
Shimano Microspline Gen 2
Shimano HG Gen 2
SRAM XDR Gen 2
There's a spacer inside the freewheel body—
must something bad have happened? (playing dumb)
This is an image I took on another day
of a Hyperon Ultra rear wheel that I
swapped to an XDR freewheel body.
I shifted it slightly to photograph the spacer,
so this is an image for this article.
Any reasonably competent person
wouldn't omit something like this.
DT hub instead (→here).
I want to explain what was wrong with the Neumen hub.
That wheel was originally built by an amateur who had the offset rim orientation reversed left and right,
so I corrected that while changing spoke gauges and relacing everything.
That was on May 23rd,
but afterward, when I tightened the thru-axle properly
(not over-tightened, but within the correct range)
the rear wheel would seize up like a fixed gear,
so in October I completely replaced the hub bearings.
After that, when I tightened the thru-axle normally again,
the rear wheel froze up once more,
and knowing it was dangerous but having no choice that day,
I loosened the thru-axle slightly and
rode home with play in the rear wheel from side to side.
The images below are from October when I replaced the bearings.
↑This is the bearing on the left side of the hub body,
and it's already been replaced here.
The bearing that was completely destroyed was the one on the freewheel body,
but the hub body bearing was also damaged
and the hub axle was wobbling slightly off-center,
so I replaced all the bearings.
I threaded the hub axle through from the right side of the hub body.
Since there are no threads cut,
the left end is a press-fit,
but it's not a simple fit tolerance—
it's a press fit relationship.
↑This is the left end viewed from the inside,
and this is press-fit all the way onto the hub axle.
The outside of the left end has threads cut for the
bearing cone adjustment nut,
and this piece alone must not be press-fit onto the hub axle, but
I did it anyway for explanatory purposes.
From this state, you cannot remove the left end by hand.
Even when the left end is fully press-fit all the way,
there's still a gap between the end and the bearing,
and in this state the hub axle can slide left and right.
The image above shows it shifted all the way to the left.
The bearing cone adjustment nut.
I installed the bearing cone adjustment nut on the left end.
The left end with the bearing cone adjustment nut
viewed from the inside.
The higher step contacts only the bearing inner race,
but since the hub bearing was damaged with off-center play,
other areas have also worn.
I turn the bearing cone adjustment nut toward the hub body
and tighten it at the point where there's just slight pressure
on the bearing inner race.
Since the left end is a very tight press-fit,
the force of pressing the bearing with the adjustment nut alone
won't pull it out of the hub axle.
Also, this bearing cone adjustment nut applies
quite a bit of force to the inner race, and since there's no place to fit a hub wrench,
you can only turn it by hand—but if you tighten it firmly,
even with brand new bearings you can make
the hub rotation quite heavy.
There seems to be one more reason for this (explained later).
↑This is the freewheel body before bearing replacement.
The seal on the outer bearing is already lifting,
and when I removed it, a cracked retainer ring came out too.
The bearing balls are heavily damaged.
I removed the front and rear bearings and
cleaned the freewheel body.
The ratchet mechanism on this hub is
the same design as the DT star ratchet
so it works by fitting the pawl ratchet components onto a spline-like surface
that's basically a square wave rounded into arcs.
On most freewheel bodies, both the front and rear bearings
are press-fit from outside the freewheel,
but on this freewheel body, the rear bearing
is press-fit from inside.
The Lief hub freewheel body that we stock for nomLab wheels
also uses the rear bearing press-fit from inside,
so it's not completely unique.
I replaced the bearings by sandwiching them
from both sides of the freewheel body.
Yellow-sealed bearings are rare,
but these are made by DT.
Now, as you might notice,
this freewheel body has no spacer inside
that contacts both bearing inner races.
I didn't forget to install it—it wasn't there from the start.
There's just no way this could withstand
normal thru-axle clamping force in any reasonable sense.
The significant heaviness that occurs from a certain point onward
when tightening the bearing cone adjustment nut
is probably partly due to this too.
I don't see how this kind of cheap, petty weight-savings benefit
outweighs the detriment of severely shortening hub lifespan.
Another manufacturer doing the same thing is
Tactic Racing's freewheel body (→here).
Another fairly significant factor to consider
is that the freewheel body is for SRAM XDR.
Because the freewheel body diameter is small,
you can't fit bearings with large outer races.
So the size difference between inner and outer races is small,
which means the balls inside are also smaller,
making them weaker under compression.
It's possible that if it were a quick-release rather than a thru-axle,
and a Shimano freewheel body, the problems would have barely occurred,
which might be why they don't include an inner race spacer
in the freewheel body.
Here are some manufacturer images:
↑This is an image of a
SRAM XD freewheel body for Neumen,
but currently there's a Gen 2 (Generation 2)
freewheel body that's separate from this.
Shimano Microspline Gen 2
Shimano HG Gen 2
SRAM XDR Gen 2
There's a spacer inside the freewheel body—
must something bad have happened? (playing dumb)
This is an image I took on another day
of a Hyperon Ultra rear wheel that I
swapped to an XDR freewheel body.
I shifted it slightly to photograph the spacer,
so this is an image for this article.
Any reasonably competent person
wouldn't omit something like this.