Bicycle Mechanics - I have no idea what I'm looking at.

I started a thread a while back about trying to get my stem out:
http://www.bikeforums.net/showthread.php?642943-Another-stem-won-t-come-out-thread

After working on it some more, I've decided I have no idea what I'm doing. So I'm back for more help. It's a Modolo Race quill stem. I thought it had a normal wedge in it, but now I think not. My usual technique for stem extraction is to back off the stem bolt and whack it or the T-wrench with a hammer, driving the bolt and wedge down. I tell if this worked by backing out the stem bolt further and seeing if the bold head is coming up as I unscrew. It seemed on this stem as though the wedge wasn't moving. So I turned the bike over, squirted a large quantity of Kroil into the hole in the fork crown, and left it for a week.

I tried it again today, no progress, so I pulled off the front brake, screwed the stem bolt into what I thought was the bottom of the wedge, and tried a slide hammer puller. Nothing. Then I got to looking closer up the hole. Now I see that the stem bolt screws into a hole threaded into a solid horizontal cylinder that's inside what I think is the stem. This cylinder turns easily on its horizontal axis, so that it's tricky to get the stem bolt threaded into it.

So looking up the hole in the fork crown, I see what I think is the end of the stem. It's a cylinder with maybe 3 mm wall thickness that touches the inside of the steer tube all the way around. Then about 6 mm from the bottom of what I think is the stem I see this solid, rotatable cylinder with the stem bolt hole drilled in it, inside of what I think is the stem. What is going on here? How does this work? What am I looking at?

The stem is still immovable by normal means. I could loosely clamp the carbon fork legs in a large wood jawed vice that I have, up near the crown, and then put a 24" crescent wrench on the stem and see what happened, but I'm nervous about doing this for fear of ruining the fork.

When I pulled the stem bolt out, I could see a residue of anti-seize on it quite clearly, so I'm pretty sure I put anti-seize on the whole assembly when I installed it years ago. But I've forgotten how this stem works!

This is my personal bike. I am not a pro bike wrench, duh. And I'm sorry about ending the title sentence with a preposition.

WIth stems u have basically two options, a wedge as the one that shows up in the picture in the previous thread or you have a expander that is a conifyed cylinder that acts like a expander. In both cases u have to lose the long screw hammer it down so the wedge or the cone thing goes down releasing the stem.

If you hammer the stem bolt the wedge should be coming lose and more over, if you take the bolt out the stem that wedge should be falling off.

Of the frame is too small stems tend to get stuck, how big is the frame? a 50? 52? Is the stem all the way down also?

Thanks

Modolo stems are much like most others.

http://img140.imageshack.us/img140/8002/blncsygmkkgrhqqokiietln.jpg

Sounds like the aluminum of the stem quill has reacted with the steel steerer and bonded. I know you say that you used anti-sieze, but it doesn't sound like it worked.
I would flip the bike over in a bike stand and try pounding the stem out from the bottom with a hammer and steel rod.

Try pounding on the screw from the top of the stem (make sure the screw is mostly undone but still engages the threads, so the screw is pushing the cone at the other end), it should push the cone downward and release the pressure. Then twist the stem repeatedly and pull upward to get it out.

As I said, I've done the pounding on the loosened stem bolt thing with a dead-blow, then a 3 lb. hammer. I put the fork legs on a wooden block, to eliminate tire bouncing, and they made substantial dents in the wood block.

So do we think that the rotatable cylinder is attached to a cone expander in the stem? Why doesn't the cone just have a threaded hole drilled in it?

Above the cylinder I see another object that is a thin-walled cylinder concentric to the cylinder of the stem proper. Is this the cone? But the rotatable cylinder doesn't seem to be inside it, rather it's below it. OTOH, the cylinder must be attached to something, because it sure doesn't move up and down. If it's a part of the cone, how is it attached to it? I don't see any cone projecting down over the ends of the cylinder.

It's an aluminum steerer on a carbon fork. In any case, it should be an aluminum cone stuck in an aluminum stem, should it not?

The stem is all the way down, so that the curve of it is touching the headset. The headset adustment nut rotates fine.

It's a 52cm frame. The bottom of the stem is about 3" above the bottom of the steerer.

As I said, I've soaked the thing in Kroil for a week. What now?

So looking up the hole in the fork crown, I see what I think is the end of the stem. It's a cylinder with maybe 3 mm wall thickness that touches the inside of the steer tube all the way around. Then about 6 mm from the bottom of what I think is the stem I see this solid, rotatable cylinder with the stem bolt hole drilled in it, inside of what I think is the stem. What is going on here? How does this work? What am I looking at?

Your full description is hard to visualize. Any way you can post a drawing or even a photo from the bottom of the hole? Perhaps a piece of the recessed brake bolt or nut fell in and got stuck a long time ago. Or just some other foreign object. Did you shine a bright flashlight into the hole? Did you actually get the stem and bolt out w/o the wedge?



Modolo stems are much like most others.

http://img140.imageshack.us/img140/8002/blncsygmkkgrhqqokiietln.jpg

Sounds like the aluminum of the stem quill has reacted with the steel steerer and bonded. I know you say that you used anti-sieze, but it doesn't sound like it worked.
I would flip the bike over in a bike stand and try pounding the stem out from the bottom with a hammer and steel rod.

However something's stuck in there, this should work: keep the bolt loose (or even out of the steerer completely), and try pounding out whatever is stuck from the back side. You have to somehow suspend and immobilize the bike and fork, of course.

It's not a foreign object. Feeling down through the stem bolt hole from the top, with a thin metal rod, I don't feel anything inside the stem except this rotatable horizontal cylinder.

I shone a very bright flashlight up the crown hole. Nothing came out of the bike except the stem bolt.

I was wrong about the fork. It's an EC50 and while the threadless have alloy steerers, the threaded style has a CroMo steerer. So maybe this rotatable cylinder is somehow the wedge and it just doesn't drop down like a normal wedge? But it is loose?

Which would mean that the problem is not with the wedge, but that the aluminum stem has corroded onto the steerer. If true, that changes the problem to how do I get the stem loose from the steerer? I obviously can't heat it internally, though I could put a torch on the exposed top of the stem. I don't care if I ruin the headset, since I'm trying to replace it.

Kroil applied from the bottom does not drip out the top.

Hammer the whole stem down with large hammer to try to break it loose?

Not a great ideea since either the wedge or cone will be forced further, and can deform the steerer tube.

Have you tried twisting the handle bars relatively to the fork? does it move?

Not a great ideea since either the wedge or cone will be forced further, and can deform the steerer tube.

Have you tried twisting the handle bars relatively to the fork? does it move?Does not move.

Pound on the underside of the stem with a hammer. It may damage the stem, but it will probably get the stem out. I have seen this work many times.

If the stem is being replaced anyway, you can easily saw through the stem with the bolt removed (leave enough stem to grab with visegrips), then remove the fork and use a torch to loosen things up.

I have had this exact same problem with this exact same stem. Loosen the stem bolt but not all the way out- there should be one or two threads still in the bottom 'cone' part. The tap the top of the bolt head- JUST THE BOLT HEAD- using a socket extension or similar metal part to ensure that ONLY THE BOLT HEAD is being struck. Use a metal hammer to tap it- not a dead blow. The cone should drop right out and presto- stem-O-remove-O.

I have had this exact same problem with this exact same stem. Loosen the stem bolt but not all the way out- there should be one or two threads still in the bottom 'cone' part. The tap the top of the bolt head- JUST THE BOLT HEAD- using a socket extension or similar metal part to ensure that ONLY THE BOLT HEAD is being struck. Use a metal hammer to tap it- not a dead blow. The cone should drop right out and presto- stem-O-remove-O.Did that. The weird cylinder thing that the stem bolt threads into does not drop down, though it rotates freely on its horizontal axis. Used a 3 lb. metal hammer and hit it quite hard, to the point that I was worried about damaging the fork legs.

Pound on the underside of the stem with a hammer. It may damage the stem, but it will probably get the stem out. I have seen this work many times.

If the stem is being replaced anyway, you can easily saw through the stem with the bolt removed (leave enough stem to grab with visegrips), then remove the fork and use a torch to loosen things up.Yes, I'm considering sawing off the stem and dropping out the forks. I'm replacing the stem anyway after this. I'll replace it with one of those quill stem adapters and use a threadless type stem.

What do you mean by the "underside of the stem?"

Put some old junk drops on there and rotate 'em back, not quite this far, but so that the ends are flat on the floor with the bike inverted
http://farm3.static.flickr.com/2308/2159176773_23fd3f9a0b.jpg?v=0
Remove front brake.
Flip the bike upside down.
Take a length of pipe with an OD that'll fit into the steerer tube, or an old, long socket extension that you don't care if it gets deformed a bit
Stick it in the steerer tube and beat on it with a hammer.

Put some old junk drops on there and rotate 'em back, not quite this far, but so that the ends are flat on the floor with the bike inverted
http://farm3.static.flickr.com/2308/2159176773_23fd3f9a0b.jpg?v=0
Remove front brake.
Flip the bike upside down.
Take a length of pipe with an OD that'll fit into the steerer tube, or an old, long socket extension that you don't care if it gets deformed a bit
Stick it in the steerer tube and beat on it with a hammer.Front brake already removed. Hole in crown is about 3/8" D. If the bars are resting on the floor, and I am beating on the bottom of the stem inside the steer tube, then I am really just beating on the bars and nothing is going to move. I'd need to rest the bike on the top tube, and I'm nervous about that, for fear of denting the top tube.

Also, the stem walls are only about 3mm, so I'm thinking that if I really beat on the bottom of the stem, I'll just deform the stem walls and maybe screw up the steer tube, or make the stem even more firmly stuck.

What do you mean by the "underside of the stem?"

I mean the underside of the horizontal extension adjascent to the handlebars. Pretty much the only place you can hit the underside with a hammer. I suspect the closer to the quill that you hit it the more directly upwards the force will act on the stem, and the greater likelyhood of getting it out.

I do not mean beat on the bototm of the quill inside the fork... that is a last resort, after cutting off the extension of the stem and reaching inside with a hacksaw blade to cut through the wall of the quill.

Good luck!

i have to agree with what was said before about the the aluminum of the stem reacting to seize within the fork. the aluminum oxide that has likely formed can be dealt with by turning the bike upside down, and pouring ammonia into it through the underside of the steerer. let this sit for a good period of time (i.e. more than 48 hrs), and tap occasionally with a hammer to help the ammonia penetrate the interface between the stem and steerer.

after it has sat, pour out the ammonia, and see if you can first twist the stem within the steerer. if it can atleast rotate within the steerer, you're within the clear and it won't be much longer till you can start pulling it out. keep the handlebars attached to the stem to give yourself more leverage.

if you need more leverage still, keep the wheel on the fork. BE CAREFUL WITH THIS however, this is generally NOT recommended unless as a last resort, since using the wheel as leverage can damage both the wheel and the fork through the torquing.

hope this helps, let us know how it goes

Cut the darn thing... take the fork out and hammer your way out from the bottom of the fork :D

How far down the quill is the stem bolt? Is it aluminium? All of the Modolo stems I've seen have aluminium bolts that are deeply recessed down the quill. You have to remove it and replace with a longer steel bolt in order to pound it with a hammer/block of wood. And a 10-lbs sledgehammer is the more appropriate tool.

How far down the quill is the stem bolt? Is it aluminium? All of the Modolo stems I've seen have aluminium bolts that are deeply recessed down the quill. You have to remove it and replace with a longer steel bolt in order to pound it with a hammer/block of wood. And a 10-lbs sledgehammer is the more appropriate tool.The bolt is a long way inside the stem, but it is steel. I used a long T-wrench (correct size) in the socket and pounded on that. If I hit it any harder, I'm afraid I'll break the fork ends loose.

One my of problems is that I'm not sure what I'm pounding on. As I said, the horizontal cylinder into which the stem bolt threads rotates easily, so does that mean that whatever wedge or expander that holds the stem in place is loose? What is that cylinder, and how does it work with the stem? Thanks . . .

Dont' rest the fork-tips on the ground! The bike should be in a workstand off the ground so you can pound on the stem-bolt with a 10-lb hammer. I've used a 15-lb hammer on some particularly stubborn stem bolts (hence the need to replace the aluminium bolts with steel ones).

Modolo stems were recalled in the early '90s due to the quill snapping right above the headset due to the LARGE hole they bored in order to recess the expander-bolt deep down inside. This severely weakens the quill.

The new designs after '92 or so didn't have as deeply recessed bolt. I'm not sure if they changed the expander cone though. Perhaps someone lost it and replaced it with something else. Can you unscrew the bolt all the way and take it out? I think you need to take a picture or draw one as this is very difficult to imagine.

Sorry, can't take a photo up that 3/8" hole in the fork crown. I haven't made the suggested drawing because I'm still not sure exactly what I'm looking at or how it's put together. I don't want to tell someone a wrong thing if I can help it.

I bought this stem new from Nashbar in about '03. Might have been NOS, I don't know. $30. Yes, the bolt was easy to remove, and screws into the bottom of the cylinder, too, which is how I was using a slide hammer puller on it.

Maybe if I put the rear wheel on a crib and grab the top tube right next to the head tube I can hit it harder without the workstand clamp spinning. I could try that, except that I'm not sure that the cylinder thing is supposed to drop down. I can't tell what it's attached to. I will make a drawing, but probably won't have it up until tomorrow.

Dont take the front wheel out... lose the bolt hammer it... lose it more... hammer it... is always noticeable when the expander is lose anyways... thats why i dont understand what are u doing. It is so simple that it is complicated apparently.

Dont take the front wheel out... lose the bolt hammer it... lose it more... hammer it... is always noticeable when the expander is lose anyways... thats why i dont understand what are u doing. It is so simple that it is complicated apparently.Yeah, if that had worked I sure wouldn't be asking about it here. It's really simple until it doesn't work.

Take it to an experienced mechanic in a good bike shop. The mechanic will have seen plenty of stuck-stem problems before and should be able to get the stem out without damage.

Hey Danno . . . I don't have to make a drawing. I didn't think the attached photo was the same as my stem, but upon looking closer, I can see that it is the exact thing. If you look closely at the wedge, you can see the end of the horizontal cylinder I've been yakking about. The wedge, instead of being solid as most are, is hollow, with about a 3mm wall thickness. It must have a thinner wall thickness than the stem, because I can see the stem above it. I thought the stem end was another structure inside the wedge, but that must be incorrect.

The purpose of the cylinder is to give a true lead for the stem bolt, even as the wedge moves from back to front to tighten the stem into place. Nice engineering, really.

So yes, I just have to get over it and really whack on that stem bolt. With luck, I won't blow the cylinder out the bottom of the wedge.

I will try that right now, now that I know what I'm looking at.

Ah, good job! That design appears to be for weight-savings and durability as well as the wedge is probably aluminium and the cylinder-insert is steel. As mentioned, most likely the aluminium wedge has corroded onto the steerer.

Got it out!

Here's what worked and what didn't work:
Worked: Grabbed the top tube in the workstand clamp close to the head tube. Loosened stem bolt and whacked on it for all I was worth with a heavy hammer. After a few minutes it started to move. Used a 3/8" bronze rod for a punch so I didn't bung up the bolt head. Backed the bolt out a bit and repeated until I was down to a few threads.

Didn't work: removed the stem bolt, turned the bike over and pounded on the bottom of the stem close to the headset, using a long 1/2" bronze rod as a punch. No movement. Pounded on the cylinder part of the wedge with a 5/16" rod and heavy hammer. No movement.

Worked: Demounted bars, and heated stem close to headset with a propane torch, wide flame, for quite a while, until the metal near the carbon fork crown started to get warm. Heard a few cracking noises while doing this, good. Of course this ruined the headset, but I had no problem with that. Then poured cold water down the inside of the stem to cool it. Lots more crackling. Pounded on the wedge again from the bottom, with the 5/16" rod and heavy hammer. This time it moved about 1/16" after several minutes of pounding. After it moved, I put the bars back on the stem and remounted the wheel and torqued on the bars. The stem moved! Then there was nothing to it - came right out.

The corrosion was just at the top of the stem and the wedge. Most of the length of the stem never got Kroil on it, and still had some anti-seize on it, very dry and dirty. I think the main effect of the heating was to make the stem longer, and longer faster than the steer tube, partly because aluminum conducts heat so well and was not well bonded to the steer tube. That broke it loose so that pounding could move it. Once it moved, it was easy.

congrats :)

With the front wheel in place, cut the stem just above the headset.
Use a large punch and hammer to drive the expander cone out of the bottom of the steerer tube.
Remove front wheel and feed a hacksaw blade through the stem then attach to a hacksaw frame.
Cut through the side of the stem from the inside.
Rotate the fork 180 degrees and cut the opposite side.

And thanks to all for their help and ideas!