Zoom adjustable threaded stem?

Alan Hoyle said:

I have a Zoom adjustable threaded stem that I'm trying to use on a
80's road/fixed gear conversion. I've got two problems with it: one real
and one potential.

The demonstrable problem is that the stem seems to be "loose" at the
adjustment joint. If I pull up to climb, the whole thing seems to pop
up a fraction of an inch. Is there some trick to tightening these
down? I can't find documentation online for torque specs.

Also, I don't have the packaging for it anymore and I'm not sure what
the clamp diameter is on it. The bars I have are 26.0 (Italian) and
it seems to clamp down well enough to where it doesn't seem to rotate,
but I don't know how I can measure the clamp.

-alan

--
Alan Hoyle - [email hidden] - http://www.alanhoyle.com/
"I don't want the world, I just want your half." -TMBG
Get Horizontal, Play Ultimate.

I have one of those stems that used to be on a hybrid I have, I don't
know the torque spec, but I had the same problem, mine seemed to loosen
over time and I just torqued the heck out of it. I think you would
really have to gorilla it to damage it.

Ken

Just A User said:

Alan Hoyle said:

[...] the stem seems to be "loose" at the adjustment joint.

[...] I just torqued the heck out of it. I think you would
really have to gorilla it to damage it.

Wow, I could not disagree more, if this is the same kind of adjustable
Zoom quill stem I bought about eight months ago.

This was the type where you tighten a bolt to draw a triangular,
ridged aluminum block up against a ribbed section of the moveable part
of the stem to lock it in place.

I was using a standard Allen key, just holding the stem in my hands
(it wasn't clamped to a stand or anything). I was just playing with
it, and voop, the threads on the aluminum wedge vanished.

Maybe I got the crappy kind, and there's a good kind, though. The
experience definitely soured me on "adjustable" anything, though.

Alan Hoyle said:

I have a Zoom adjustable threaded stem that I'm trying to use on a
80's road/fixed gear conversion. I've got two problems with it: one real
and one potential.

The demonstrable problem is that the stem seems to be "loose" at the
adjustment joint. If I pull up to climb, the whole thing seems to pop
up a fraction of an inch. Is there some trick to tightening these
down? I can't find documentation online for torque specs.

I've only used the threadless version of this stem. I heavily greased
every mating surface of the clamp parts to make sure there would be no
creaking and no binding when the bolt was tightened down. I had no
problems for the few months of service I put it to use.

amakyonin said:

Alan Hoyle said:

I have a Zoom adjustable threaded stem that I'm trying to use on a
80's road/fixed gear conversion. I've got two problems with it: one real
and one potential.

Quoted message said:

The demonstrable problem is that the stem seems to be "loose" at the
adjustment joint. If I pull up to climb, the whole thing seems to pop
up a fraction of an inch. Is there some trick to tightening these
down? I can't find documentation online for torque specs.

I've only used the threadless version of this stem. I heavily greased
every mating surface of the clamp parts to make sure there would be no
creaking and no binding when the bolt was tightened down. I had no
problems for the few months of service I put it to use.

The loose one I saw (think it was Zoom, but not sure) used plastic
teeth in the gearing. The plastic teeth were partially stripped. If I
were U, I'd disassemble it to inspect exactly what the problem is. If
it is worn plastic gear teeth, I wouldn't ride it. Although I don't
know how catastrophically they may or may not fail. It may be possible
to order only the plastic gear for replacement.

Good luck, John

Alan Hoyle said:

I have a Zoom adjustable threaded stem that I'm trying to use on a
80's road/fixed gear conversion. I've got two problems with it: one real
and one potential.

The demonstrable problem is that the stem seems to be "loose" at the
adjustment joint. If I pull up to climb, the whole thing seems to pop
up a fraction of an inch. Is there some trick to tightening these
down? I can't find documentation online for torque specs.

All adjustable stems do this, they're [censored]. You're much better of (and
safer!) to get the measurements from the adjustable stem then purchasing
an standard stem in that shape.

Cheers

Joel

Alan Hoyle said:

I have a Zoom adjustable threaded stem that I'm trying to use on a
80's road/fixed gear conversion. I've got two problems with it: one real
and one potential.

The demonstrable problem is that the stem seems to be "loose" at the
adjustment joint. If I pull up to climb, the whole thing seems to pop
up a fraction of an inch. Is there some trick to tightening these
down? I can't find documentation online for torque specs.

Also, I don't have the packaging for it anymore and I'm not sure what
the clamp diameter is on it. The bars I have are 26.0 (Italian) and
it seems to clamp down well enough to where it doesn't seem to rotate,
but I don't know how I can measure the clamp.

-alan

--
Alan Hoyle - [email hidden] - http://www.alanhoyle.com/
"I don't want the world, I just want your half." -TMBG
Get Horizontal, Play Ultimate.

Hello,

I have a Jamis Coda with an adjustable stem and I had the same problem
last year.I can't remember which, but I either pulled up or pushed
down on the stem as I tightened the adjuster bolt, and the stem was
solid after that. Just a week ago I adjusted the bike and had the same
problem, totally forgetting what had worked the last time. I played
around for a bit, and "rediscovered" that trick. Since it worked twice
I don't think it was just a fluke, but it seems odd that pulling up or
pushing down would help.

My stem looks kinda like this one: http://nordicgroup.us/bikerec/images/stem2.gif
; on mine the bolt on the side loosens to adjust, and tightens to lock
into that position. I'm not familiar with other styles of adjustable
stems, so I don't know if they adjust via a similar mechanism or not.

Hope this helps,

Sean C.

Quoted message said:

Quoted message said:

Alan Hoyle said:

[...] the stem seems to be "loose" at the adjustment joint.

Quoted message said:

Just A User said:

[...] I just torqued the heck out of it. I think you would
really have to gorilla it to damage it.

Quoted message said:

Wow, I could not disagree more, if this is the same kind of adjustable
Zoom quill stem I bought about eight months ago.

This was the type where you tighten a bolt to draw a triangular,
ridged aluminum block up against a ribbed section of the moveable part
of the stem to lock it in place.

I was using a standard Allen key, just holding the stem in my hands
(it wasn't clamped to a stand or anything). I was just playing with
it, and voop, the threads on the aluminum wedge vanished.

Maybe I got the crappy kind, and there's a good kind, though. The
experience definitely soured me on "adjustable" anything, though.

These are not cold forged Italian equipment but they have been supplied
to the millions of pieces per year an new bikes for quite a while and
failure rates are low.

The wedge doesn't have threads. Did something fail? Just wondering.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

Joel Mayes said:

Alan Hoyle said:

I have a Zoom adjustable threaded stem that I'm trying to use on a
80's road/fixed gear conversion. I've got two problems with it: one real
and one potential.

The demonstrable problem is that the stem seems to be "loose" at the
adjustment joint. If I pull up to climb, the whole thing seems to pop
up a fraction of an inch. Is there some trick to tightening these
down? I can't find documentation online for torque specs.

All adjustable stems do this, they're [censored]. You're much better of (and
safer!) to get the measurements from the adjustable stem then purchasing
an standard stem in that shape.

FWIW, I've sold bikes with Ritchey and even Kalloy without a single
complaint. They certainly add an element of adjustability to a bike
that doesn't exist otherwise, and are a valid way to determine the
"right stem" even if you plan on replacing it with a lighter "fixed
stem" later on.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

On Wed, 11 Apr 2007 18:09:28 -0500, A Muzi <[email hidden]>

Quoted message said:

Quoted message said:

Wow, I could not disagree more, if this is the same kind of adjustable
Zoom quill stem I bought about eight months ago.

This was the type where you tighten a bolt to draw a triangular,
ridged aluminum block up against a ribbed section of the moveable part
of the stem to lock it in place.

I was using a standard Allen key, just holding the stem in my hands
(it wasn't clamped to a stand or anything). I was just playing with
it, and voop, the threads on the aluminum wedge vanished.

These are not cold forged Italian equipment but they have been supplied
to the millions of pieces per year an new bikes for quite a while and
failure rates are low.

The wedge doesn't have threads. Did something fail? Just wondering.

If it's the same problem I had, the aluminum threads in the stem body
stripped. Took me a couple years to break it, and to be honest, I
wonder if it was my fault for not tightening the bolts on either side
of the bars evenly. (The Nitto I replaced it with is lovely, though!)

Pat

Email address works as is.

Mark Hickey said:

Joel Mayes <[email hidden]> wrote:

Quoted message said:

Quoted message said:

Alan Hoyle said:

I have a Zoom adjustable threaded stem that I'm trying to use on a
80's road/fixed gear conversion. I've got two problems with it: one real
and one potential.

The demonstrable problem is that the stem seems to be "loose" at the
adjustment joint. If I pull up to climb, the whole thing seems to pop
up a fraction of an inch. Is there some trick to tightening these
down? I can't find documentation online for torque specs.

All adjustable stems do this, they're [censored]. You're much better of (and
safer!) to get the measurements from the adjustable stem then purchasing
an standard stem in that shape.

Quoted message said:

FWIW, I've sold bikes with Ritchey and even Kalloy without a single
complaint. They certainly add an element of adjustability to a bike
that doesn't exist otherwise, and are a valid way to determine the
"right stem" even if you plan on replacing it with a lighter "fixed
stem" later on.

This is what I'm going to do. It turns out that the model stem I have
is indeed a 25.4mm clamp, but the handlebars are 26.0mm diameter. It
seems like it fits, but I don't think it's a good idea to keep this
setup.

Now I just need to decide if I'm going to get a regular threaded stem
or get a threaded to threadless adapter, move the stem from my road
bike, and "upgrade" that stem. Clearly the cheaper way would be the
former, but I have wanted to get a stem 1-2 cm longer for the road
bike...

Thanks for the advice all.

-alan

--
Alan Hoyle - [email hidden] - http://www.alanhoyle.com/
"I don't want the world, I just want your half." -TMBG
Get Horizontal, Play Ultimate.

Patrick Lamb said:

On Wed, 11 Apr 2007 18:09:28 -0500, A Muzi <[email hidden]>

Quoted message said:

The wedge doesn't have threads. Did something fail? Just wondering.

If it's the same problem I had, the aluminum threads in the stem body
stripped.

I went out to my garage this morning to have a look, but I'm pretty
sure I threw it out. I'm sure you're right; I can envision the bolt
passing through the wedge and threading into the stem.

So, it must have been the threads in the stem that stripped. I was
even thinking to myself, "I should be careful". I'm not Mozart with a
wrench or anything, but I've never stripped anything that easy before
that wasn't made of cheese. Maybe I got a bum part.

Quoted message said:

Patrick Lamb said:

On Wed, 11 Apr 2007 18:09:28 -0500, A Muzi <[email hidden]>

Quoted message said:

The wedge doesn't have threads. Did something fail? Just wondering.

If it's the same problem I had, the aluminum threads in the stem body
stripped.

I went out to my garage this morning to have a look, but I'm pretty
sure I threw it out. I'm sure you're right; I can envision the bolt
passing through the wedge and threading into the stem.

So, it must have been the threads in the stem that stripped. I was
even thinking to myself, "I should be careful". I'm not Mozart with a
wrench or anything, but I've never stripped anything that easy before
that wasn't made of cheese. Maybe I got a bum part.

Not necessarily. Mine had a bit of slop around the bar, so you could
(and I probably did) screw it tight on one side, getting full engagement
of the bolt on that side, and then get only about half that much
engagement on the other side of the bar. With a bit of time, that
slowly stripped the threads, and when I readjusted, there was only the
other half of the threads left to hold it, which then stripped a bit faster.

Looking back, I suspect things would have been fine if Kalloy (or me)
had used bolts that were about 1/4" to 1/2" longer. But that would have
added 2 cents to the cost of the stem, and it wouldn't have been quite
so neat looking with bolts sticking out the bottom.

Pat