Shim orientation with a 1" steerer

I have an all-carbon fork with a 1" steerer tube, and am using a shim to
allow me to use a 1 1/8" ITM Millenium stem. The question is, should the
slot in the shim line up with the slot at the back of the stem (i.e.,
facing the back of the bike) or should it be placed opposite the slot in
the stem (i.e., facing the front of the bike)?

Also, the shim that came with the stem seems to be fairly crude - it is
less circular than either the steerer or the inside of the stem: is this
likely to cause problems, or when it's tight will everything be just fine?

Thanks in advance,

Tom

Tom Wright wrote:
I have an all-carbon fork with a 1" steerer tube, and am using a shim
to
allow me to use a 1 1/8" ITM Millenium stem. The question is, should
the
slot in the shim line up with the slot at the back of the stem (i.e.,

facing the back of the bike) or should it be placed opposite the slot
in
the stem (i.e., facing the front of the bike)?

Also, the shim that came with the stem seems to be fairly crude - it
is
less circular than either the steerer or the inside of the stem: is
this
likely to cause problems, or when it's tight will everything be just
fine?

Thanks in advance,

Tom

Slot should go toward the back. It enables you to see the amount of
compression on the shim. In other words, if the shim is oversized, you
will be able to see it compress in the slot of the stem. Structurally,
doesn't really matter though, Michal Knudsen

Tom Wright wrote:
I have an all-carbon fork with a 1" steerer tube, and am using a shim to
allow me to use a 1 1/8" ITM Millenium stem. The question is, should the
slot in the shim line up with the slot at the back of the stem (i.e.,
facing the back of the bike) or should it be placed opposite the slot in
the stem (i.e., facing the front of the bike)?

Also, the shim that came with the stem seems to be fairly crude - it is
less circular than either the steerer or the inside of the stem: is this
likely to cause problems, or when it's tight will everything be just fine?

Thanks in advance,

Tom

Either front or back is correct but don't put the slot on the side.
Your bike will tip over if you do.

Tom Wright wrote:
I have an all-carbon fork with a 1" steerer tube, and am using a shim to
allow me to use a 1 1/8" ITM Millenium stem. The question is, should the
slot in the shim line up with the slot at the back of the stem (i.e.,
facing the back of the bike) or should it be placed opposite the slot in
the stem (i.e., facing the front of the bike)?

Also, the shim that came with the stem seems to be fairly crude - it is
less circular than either the steerer or the inside of the stem: is this
likely to cause problems, or when it's tight will everything be just fine?

Remove any sharp edges on the shim and turn it so it does
not line up with the other slit.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

Tom Wright asked:

I have an all-carbon fork with a 1" steerer tube, and am using a shim
to allow me to use a 1 1/8" ITM Millenium stem. The question is,
should the slot in the shim line up with the slot at the back of the
stem (i.e., facing the back of the bike) or should it be placed
opposite the slot in the stem (i.e., facing the front of the bike)?

Also, the shim that came with the stem seems to be fairly crude - it
is less circular than either the steerer or the inside of the stem: is
this likely to cause problems, or when it's tight will everything be
just fine?

Andy Muzi replied

Remove any sharp edges on the shim and turn it so it does not line up
with the other slit.

Hmmm...Why should the slits not be lined up with one another? That
would have seemed to me to be the obvious way to do it.

I recall seeing bikes with separate seatpost clamping collars where
users would put the slit in the collar at 180 degrees from the slit in
the seat tube. This would generally result in insufficient clamping
force on the seat post.

I'll admit to having no experience with plastic steerers. I also want
no experience with plastic steerers, especially not in the 1" size. I'm
not a daredevil.

Sheldon "Curious" Brown
+---------------------------------+
| If you understand everything, |
| you must be misinformed. |
| --Japanese Proverb |
+---------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

Tom Wright asked:
I have an all-carbon fork with a 1" steerer tube, and am using a shim
to allow me to use a 1 1/8" ITM Millenium stem. The question is,
should the slot in the shim line up with the slot at the back of the
stem (i.e., facing the back of the bike) or should it be placed
opposite the slot in the stem (i.e., facing the front of the bike)?
Also, the shim that came with the stem seems to be fairly crude - it
is less circular than either the steerer or the inside of the stem:
is this likely to cause problems, or when it's tight will everything
be just fine?

Andy Muzi replied
Remove any sharp edges on the shim and turn it so it does not line up
with the other slit.

Sheldon Brown wrote:
Hmmm...Why should the slits not be lined up with one another? That
would have seemed to me to be the obvious way to do it.

I recall seeing bikes with separate seatpost clamping collars where
users would put the slit in the collar at 180 degrees from the slit in
the seat tube. This would generally result in insufficient clamping
force on the seat post.

I'll admit to having no experience with plastic steerers. I also want
no experience with plastic steerers, especially not in the 1" size. I'm
not a daredevil.

Sheldon "Curious" Brown

I've seen them every which way. And very few failures.

Where I was going with that was to avoid a situation where
the edges of the slit dig into the steerer, less likely if
the slits aren't lined up. Especially with stems that are
thin, the edges under the clamping bolts do tend to dig in.

Recently, in a long discussion with a manufacturer, trying
to get a straight answer on recommendations for securing
their carbon bars, that seemed the gist of their concern.
Just ensure there aren't sharp edges and make sure the edges
or corners don't 'dig in'. In the two cases I've seen of
split carbon bars, the cracks started with a faceplate
tightened unevenly so one edge notched the handlebar.

If we can keep clamping pressure evenly distributed we're
ahead I think. If it were a nice beefy stem turning the
slits to line up shouldn't matter.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

A Muzi wrote:
Tom Wright asked:

I have an all-carbon fork with a 1" steerer tube, and am using a
shim to allow me to use a 1 1/8" ITM Millenium stem. The question
is, should the slot in the shim line up with the slot at the back of
the stem (i.e., facing the back of the bike) or should it be placed
opposite the slot in the stem (i.e., facing the front of the bike)?
Also, the shim that came with the stem seems to be fairly crude - it
is less circular than either the steerer or the inside of the stem:
is this likely to cause problems, or when it's tight will everything
be just fine?

snip

I've seen them every which way. And very few failures.

ahh, which gets to the original motivation for my post...

Where I was going with that was to avoid a situation where the edges of
the slit dig into the steerer, less likely if the slits aren't lined
up. Especially with stems that are thin, the edges under the clamping
bolts do tend to dig in.

This is exactly what I found when I took apart my headset for regreasing
last night - the shim has dug into the steerer by perhaps as much as 1mm
I'm now trying to decide whether I fitted it wrongly, or whether it
was just bad luck. I did do the bolts up pretty tightly, but only
because the headset was working loose over the course of a few rides
when they weren't so tight.

Recently, in a long discussion with a manufacturer, trying to get a
straight answer on recommendations for securing their carbon bars, that
seemed the gist of their concern. Just ensure there aren't sharp edges
and make sure the edges or corners don't 'dig in'. In the two cases
I've seen of split carbon bars, the cracks started with a faceplate
tightened unevenly so one edge notched the handlebar.

I did sand the shim before inserting it, but perhaps didn't round off
the edges as much as I could/should have done.

If we can keep clamping pressure evenly distributed we're ahead I
think. If it were a nice beefy stem turning the slits to line up
shouldn't matter.

So the question now is get another full carbon fork, go for a carbon
fork with steel/alloy steerer, or just get a full steel fork (frame is
Columbus Nivecrom steel). Can't say I'm that keen on the first option
(especially since the other options are cheaper and the fork I had was
less than 2 years old). Suggestions welcome

Would it be safe to cut off the notched bit of the steerer and use the
fork on a frame with a shorter head-tube/fewer spacers?

Thanks for all the replies so far,

Tom

Tom Wright wrote:

So the question now is get another full carbon fork, go for a carbon
fork with steel/alloy steerer, or just get a full steel fork (frame is
Columbus Nivecrom steel). Can't say I'm that keen on the first option
(especially since the other options are cheaper and the fork I had was
less than 2 years old). Suggestions welcome

In my opinion, only a fool would buy a fork with a plastic steerer.

Sheldon "Risk/Benefit" Brown
+--------------------------------------------+
| To see what is in front of one's nose |
| needs a constant struggle |
| --George Orwell |
+--------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

Sheldon Brown wrote:

I'll admit to having no experience with plastic steerers. I also want
no experience with plastic steerers, especially not in the 1" size. I'm
not a daredevil.

Something I've always wondered about (something that Sheldon brings up
above...).

What is it that makes anyone assume that a fork manufacturer would
have different ultimate strength specs for their forks with different
size steer tubes? In other words, why would they say "x" is fine in
terms of ultimate strength for a 1" fork, but in order to release a
1-1/8" fork, the ultimate strength must be 1.y?

My contention is that no matter what the size of the steer tube, the
manufacturer has done the testing and has determined how best to build
a fork that will withstand whatever will be asked of it, no matter if
the steer tube is 1", 1-1/8", or 1-1/4".

I, for the life of me, can't imagine why they'd do otherwise.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

Mark Hickey wrote:
Sheldon Brown wrote:


I'll admit to having no experience with plastic steerers. I also want
no experience with plastic steerers, especially not in the 1" size. I'm
not a daredevil.


Something I've always wondered about (something that Sheldon brings up
above...).

What is it that makes anyone assume that a fork manufacturer would
have different ultimate strength specs for their forks with different
size steer tubes? In other words, why would they say "x" is fine in
terms of ultimate strength for a 1" fork, but in order to release a
1-1/8" fork, the ultimate strength must be 1.y?

it's not just the ultimate strength, it's the stiffness too. 1"
steerers can be just as strong as 1.125", but the larger diameter is
stiffer, in exactly the same way as large tube diameter frames are
stiffer than standard tube diameter frames. both are engineered for
about the same ultimate strength.

my preference in carbon forks is to have one with a steel steerer for 1"
frames, carbon or aluminum steerers for 1.125" or greater frames, based
on stiffness.


My contention is that no matter what the size of the steer tube, the
manufacturer has done the testing and has determined how best to build
a fork that will withstand whatever will be asked of it, no matter if
the steer tube is 1", 1-1/8", or 1-1/4".

I, for the life of me, can't imagine why they'd do otherwise.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame