jPrichard10 

This should be an easy one.

Picked up a Cinelli stem from the Co-op for some Cinelli bars I have (26.4).

Someone tightened the handlebar bolt down, and I can't unscrew it enough to remove it or get handlebars in. Turning the bolt from the back only causes the front to spin:





I tried leveraging the stem "open" as I unscrew to give some more purchase to the nut, but hard to do with just two hands and also makes it difficult to apply the right amount of pressure that lets me turn the bolt.

John Nolan 

Dremel a slot?

jPrichard10 

​​​​​​I'd prefer something that isn't altering the stem this drastically, and figured with how many Cinelli stems are out there that there would be some easy trick that all the Italophiles are doing.

John Nolan 

Yes, I hope someone does have better idea ;-)

wrk101

If the entire bolt is spinning, time to drill the bolt out. You will need a drill press.

Kabuki12

Possibly hold the bolt with the wrench and carefully hacksaw through the clamping slot . I’m not sure how hard the bolt is but use a new fine pitch blade.

jPrichard10 

Dang, was hoping this was easier than replacing the bolt.

What normally prevents the bolt from spinning? I assumed it was knurled in some way on the inside?

Kabuki12

Either knurled or keyed. I really can’t remember. You may try penetrating oil and tapping on it while gently turning the wrench back and forth . ATF mixed with acetone is great if you don’t have Marvel Mystery Oil. Vibration helps the penetrating oil penetrate. I use a brass hammer for this

jPrichard10 

Okay, looking up replace bolts ($60! Bonkers) I now see what I'm working with here. For such a storied piece of equipment, this seems like one of the dumbest designs.

I suppose sawing through would allow me to salvage the nut (if it's worth salvaging; clearly it has no "bite" left) and maybe replace the bolt.

Would be nice if someone made little shiny Allen bolt caps. Then you could have an Allen head on either side and plug the cap when you're done. Plus think of all the money you'd make reselling caps when they eventually rattle out of the stem!

It seems like a whole new stem may be my cheapest option here, unless someone has some really creative ideas.

Kabuki12

Hit the smooth head with a sacrificial bolt and hammer to try to lodge it into the stem hole . The serration should still be there and may just need to be driven in.

Kabuki12

For sixty bucks you could probably buy a complete stem!

obuckler

Maybe a SMALL drop or two of permanent loctite under the front cap delivered at end of a toothpick and apply pressure to create anerobic-ness so it will lock. Danger is too much and you lock the threads more.

Worth a try, but a long shot…

Do you think you might have a 26 bar in a 26.4 stem that created over-tightness?

jPrichard10 

This bar and stem are both new to me, but I'm certain the bar is 26.4 the stem fits onto the sleeve, but I would mar the sleeve if I forced it any more. Plus I wouldn't be able to tighten the pinch bolt anyway even if I got the stem in place!

I tried hitting the bolt head into place with another bolt and it still spins, but I did a good job of marring the nice clean face of the bolt... Might try the locktite trick? I'm about ready to just find another stem.

SurferRosa

Friction on the nut is needed. Pry a 3 or 4mm allen key in there to add friction while you turn the bolt.

And/or check this thread to see if you can find a replacement or replacement parts:

A Stem Exchange Thread

oneclick 

a) Spread the clamp better:
Two large screwdrivers of the flat-blade variety may work, opposed, as wedges; arrange it so they will stay in position after you tap them together
I'd find a way to hold the stem in a vice and support the handle ends.
It should be pretty easy to adjust the amount and it may be enough to break the screw free.

b) Saw the screw & nut:
You'll need to keep the screw from rotating.
Put a hex key in the screw socket, and fix it to the stem with a hose-clamp, then put the stem in your vice and hack away.

Trakhak

Slide a handlebar into the stem and twist as if you were trying to get the handlebar to wobble, while turning the bolt with the Allen wrench. Maybe use a full-circumference soda can shim to protect the bar. (Probably a 3- or 4-hand operation, so have a helper nearby.) Make sure that the handlebar fits pretty tightly in the stem before applying the twisting pressure.

You should be able to apply enough pressure to force the stem farther open, thus seating the knurled portion of the stem bolt

gearbasher

I only use Cinelli 1A stems and most of the bolts were keyed. I only had one that was knurled. I just thought I would throw this in.

John Nolan 

Is it possible that isn't the right bolt? Looking at it, I would have expected it to be closer to flush with the front of the stem.

velomateo

I would suggest using a non metallic wedge or shim to spread the opening, that would add some pressure against the forward nut.
You may find plastic shims or scrapers (that could be modified to the width you need) at the local hardware store.
Once wedged in, you should be able to work hands free.

repechage

Only if you have a drill press - punch center of stem nut and Kroil it, the hopefully enough depth to use an easyout. I do not see using this nut again, maybe the bolt.
‘I have one right now that is recalcitrant, but it is half way out. Hoping to avoid destructive methods. This seems to happen most often when the 26.4 stem was paired to a 26.0 bar.

Mr. 66

I would try a pair of hemostats, the thin surgical steel pliers may have enough grip to hold for removing

Mad Honk 

I think there is an easier way than all of the destructive methods being proposed. Take a small nut and epoxy it to the spinning part. You can then use the nut as a leverage method to remove the bolt. When finished heat the epoxy, it breaks down at 350* so the nut can be removed. Then clean the chrome with something like Simichrome, or Quick Glo chrome polish. HTH, MH

Kabuki12

If his bolt is the same as what is pictured , he would be holding the wrong side of the fastener.

jPrichard10 

Wow, lots of ideas here!

My sacrificial bolt marred the chrome a bit when K was trying to hammer it to get the knurls to bite.

I agree, it does look like the nut isn't flush with the end; maybe it's the wrong one? The stem is as I found it at the co-op, so no knowing if it was original or not.

​​​​​​I may try the epoxy trick if various wedges don't work.

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SJX426 

One of my 1A stems