Trobules changing a headset...

"Ben Blaukopf" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I've unscrewed the locknut, the nut below that (the race?), and the long
vertical screw that runs from the stem down into the forks (the stem
bolt).

Oops. The stem bolt holds a wedge. You need to undo it a bit, then hit it to
dislodge the wedge.

http://sheldonbrown.com/handsup.html has a picture.

I'd try putting the bolt back in then hitting it. Or put the bolt in as far
as it will go, since you can't find the end.

(actually, if you can't find the end, has the wedge dropped off? Does the
bolt bottom out? If so, you just need to free the stem from the forks, which
possibly involves GBH. Handlebars and wheel help here.)

cheers,
clive

Ben Blaukopf said:

Bike is a Marin Larkspur, which is a hybrid bike with a threaded
headset. The stem goes all the way down into the headset. The headset
creaks, so I bought a new one from my LBS (they will be my next port of
call, but are trickier to get to than usenet. Have tried google, of
course). The bike is about 4 yrs old and has had no headset maintenance
for at least 3 years.

I've unscrewed the locknut, the nut below that (the race?), and the long
vertical screw that runs from the stem down into the forks (the stem bolt).

It's a quill stem. The long vertical screw (haven't had one of them
for _ages_) either engages in a wedge shaped nut, which pulls against
a wedge shaped face, or into a conical nut which pulls into a split
tube. The action of doing up the screw expands either mechanissm to
squeeze againstthe steerer. The way to do it isto undo the screw a
couple of turns then thwack it, using a block of wood to protect the
top end. This frees the wedge.

Quoted message said:

As I understand it, the forks should now drop out. No such luck. They
don't even twist relative to the stem.

So I gave up for the night, and put the bike back together. Except the
stem bolt won't engage with anything. I can put it all the way in, but
there's no corresponding thread for it to connect to.

A bit of fiddling around should re-engage the screw into the wedge.

Tim

Ben Blaukopf said:

I've unscrewed the locknut, the nut below that (the race?), and the long
vertical screw that runs from the stem down into the forks (the stem bolt).

As I understand it, the forks should now drop out. No such luck. They
don't even twist relative to the stem.

Have you actually removed the stem? If I've understood you correctly,
which I'm not sure I have, it sounds like the stem may be "seized" (aka
rusted) into the steerer tube, in which case you need to apply some
kind of penetrating oil to free it. And/or a lot of force.

In any case, you won't be able to remove the fork before you remove the
stem. Once you have removed the stem, you should then only have to undo
the top locknut to release the fork. The top bearing race will be held
in place by the locknut - I don't think this screws on, though I may be
wrong.

Quoted message said:

So I gave up for the night, and put the bike back together. Except the
stem bolt won't engage with anything. I can put it all the way in, but
there's no corresponding thread for it to connect to.

I think what Tim says is right - the wedge-shaped nut that the stem
bolt screws into has probably dropped down inside the fork. If you turn
the bike upside-down then attempt to screw the stem bolt back in, you
may have more luck.

Quoted message said:

I don't really understand how everything fits together. I've unscrewed
everything I can see. Any suggestions gratefully received!

<url:http://www.parktool.com/repair_help/howfix_headset.shtml>

d.

in message <[email hidden]>, Ben Blaukopf

(') said:

Bike is a Marin Larkspur, which is a hybrid bike with a threaded
headset. The stem goes all the way down into the headset. The headset
creaks, so I bought a new one from my LBS (they will be my next port of
call, but are trickier to get to than usenet. Have tried google, of
course). The bike is about 4 yrs old and has had no headset maintenance
for at least 3 years.

I've unscrewed the locknut, the nut below that (the race?), and the
long vertical screw that runs from the stem down into the forks (the
stem bolt).

Nope. Don't remove the long vertical bolt. If you remove it you can't
knock the wedge loose, and, indeed, now you've removed it you may find
it exceedingly awkward to get back in. But do that. Put it back in,
screw it up until tight, and then back off about three or four turns.
Then tap it gently on the top with a wooden or rubber mallet. This
should knock the wedge loose. If it doesn't, hit the bolt with
progressively bigger and more bludgeonly things until it does.

*Then* you can get the stem out.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/
;; If Python is executable pseudocode,
;; then Perl is executable line noise
-- seen on Slashdot.

Simon Brooke said:

Nope. Don't remove the long vertical bolt. If you remove it you can't
knock the wedge loose, and, indeed, now you've removed it you may find
it exceedingly awkward to get back in. But do that. Put it back in,
screw it up until tight, and then back off about three or four turns.
Then tap it gently on the top with a wooden or rubber mallet. This
should knock the wedge loose. If it doesn't, hit the bolt with
progressively bigger and more bludgeonly things until it does.

*Then* you can get the stem out.

If it's an expander bolt rather than a wedge, loosen the bolt a turn or
two and wrestle the stm out of the headset (being careful not to bend
the front wheel as you do so). Expanders are the work of Stan.

Simon Brooke said:

in message <[email hidden]>, Ben Blaukopf

(') said:

Bike is a Marin Larkspur, which is a hybrid bike with a threaded
headset. The stem goes all the way down into the headset. The headset
creaks, so I bought a new one from my LBS (they will be my next port of
call, but are trickier to get to than usenet. Have tried google, of
course). The bike is about 4 yrs old and has had no headset maintenance
for at least 3 years.

I've unscrewed the locknut, the nut below that (the race?), and the
long vertical screw that runs from the stem down into the forks (the
stem bolt).

Nope. Don't remove the long vertical bolt. If you remove it you can't
knock the wedge loose, and, indeed, now you've removed it you may find
it exceedingly awkward to get back in. But do that. Put it back in,
screw it up until tight, and then back off about three or four turns.
Then tap it gently on the top with a wooden or rubber mallet. This
should knock the wedge loose. If it doesn't, hit the bolt with
progressively bigger and more bludgeonly things until it does.

*Then* you can get the stem out.

I turned the bike upside down and removed the front reflector to get
access to the forks. There was an expanding bolt loose some way inside -
couldn't remove it completely, but managed to push it back in and
reconnect the stem bolt. So I now have a vaguely safe bike again. Gave
up on trying to remove the stem which appears to be completely seized.
I'll let the LBS deal with it!

Ben