Bicycle Mechanics - Attaching a Stem

I received a 1979 Motobecane on Friday. While reassembling the bike, I noticed the top bolt on the stem doesn't connect to anything... it just drops in the hole and moves around. I took the stem back off and the hole is wide open all the way until the brake bolt. I've never done one of these before so I don't know what's supposed to be there. Is it missing a part?

This is the bolt I am talking about:

http://i349.photobucket.com/albums/q364/Netdewt/bikes/6a02_3.jpg

The stem should have a wedge or expander on the bottom as pictured

http://www.sheldonbrown.com/images/stems333-220.gif

tightening the top bolt either causes the wedge or expander to lock the stem into place in the steerer tube of the fork.

It is very likely you have simply dropped the expander (as described by jsharr) inside the frame... turn the bike over and see if it falls out easily, or maybe take the loose bolt out of the stem and use it to try to push the expander out from the bottom. Any long thin object will do if the stem bolt does not - a straightened coathanger is one of my favourite tools for this type of job.

Also, I would love to see some pics of the bike :)

It doesn't look like that at all (flat on bottom with a vertical notch):

http://i349.photobucket.com/albums/q364/Netdewt/bikes/stem.jpg

PS, it's a Specialized stem.

yours is the expander type and you are missing the expander. It would be a cone shaped piece with a hole in the middle for the bolt.

http://i349.photobucket.com/albums/q364/Netdewt/bikes/68a6_3.jpg

This pic is from the sale. Got it for $255 + shipping on eBay. It's a Motobecane Jubile Sport with Shimano 600 components, Mavic G40 rims, Campy hubs, Cinelli bars.

I went to a bicycle junkyard and had no luck whatsoever. I don't even know if I would know what I'm looking for because I haven't seen the expander apart from the stem. The people at the shop where the junkyard is were not helpful at all.

Would either of these work (bikepartsusa.com)? How do I find out what size I need?

http://www.bikepartsusa.com/mas_assets/full/01-82268.jpg

http://www.bikepartsusa.com/mas_assets/full/01-82325.jpg

I really didn't want to have to order online...

I do not see how the expander could have gone missing - you implied you worked on it so maybe it is laying around somewhere?

Neither of your picture will work with your stem AS IS. That is, you use a expander and your top pic is a wedge and your bottom pic is a wedge with the bolt and a washer. You can replace the whole stem to a wedge systemm, but if you just want the part you need an expander.

I do not see how the expander could have gone missing - you implied you worked on it so maybe it is laying around somewhere?

Neither of your picture will work with your stem AS IS. That is, you use a expander and your top pic is a wedge and your bottom pic is a wedge with the bolt and a washer. You can replace the whole stem to a wedge systemm, but if you just want the part you need an expander.

No, I bought the bike on eBay and the expander is NOWHERE. I searched high and low, so did the seller. It disappeared.

Sorry, I thought maybe those looked less wedgelike than the others I've found. I can't find anyone who sells the expander, and I have no idea what an expander looks like.

It looks like a used cork for a wine bottle, with maybe a smoother taper instead of the bulging and has a threaded hole in the middle, incidentally like a cork that got pulled out. It is metal though, and usually heavy. A well equipped LBS with a parts bin might have one sitting around, and if so they'll probably give it to you for free.

At this point then I would ask the seller to provide you with a working stem and let him file a claim for loss/damage with his shipper. Internal stem expanders are not an easy find. Wedges, as you have found are a much easier find. A machine shop could fabricate one for you, but it would be easier and cheaper to just buy a new stem.

While it's an option to do that it seems like overkill over an expander.

The wine cork image isn't eally that accurate either since wine corks are generally cylindrical. The expander is strongly tapered and more like a rubber cork for flasks like you used back in chemistry class. Even down to the hole in the center. But in this case the center hole is threaded for the rod. The wedge types you showed in your picture won't work at all for your stem even if they do look less wedge like.

If you're handy with tools you can even make your own. Find a little round slug of steel and drill and thread for the bolt. Then hacksaw and file it to a roughly round tapered cork shape. Just do it by eye taking care to try to make it as round as you can and it'll work just fine.

Any bike that that's been around for more than 10 years will have something like this or can sell you a used stem of the shape shape and reach for around $5 to $15. If they want more than that for a used one go find another shop.

Alternately take your request for a spare expander to the vintage guys. I'm sure there's someone that could mail you one for a couple of bucks to get this old girl up and riding again.

Oh... here's a really silly thought...

Take out the stem again and look down inside the steer tube. I'll just bet you that the expander fell out when the seller removed the stem and it's stuck down inside the steer tube. It wouldn't fall all the way through since the front caliper bolt is in there. And if it got cocked over sideways and vibrated enough in shipping it may well be lightly wedged in there. If you remove the front wheel and then prod the big dark thing out from below with a very narrow and long screwdriver it should come loose and you can rattle it out. Or once it's loose turn the whole bike over so it falls out.

I definitely realize not to go to far with it. I'd just buy this if it got ridiculous: http://www.bikepartsplace.com/discount/handlebar-stem-1a-silver/

Then I'd have Cinelli bars AND stem. Heh. I'll make a separate post for the C&V guys.

Go check down inside the steer tube first. Knowing how these can stick and knowing that the guy taking the stem out didn't know about how this stuff works I'll bet it's in there.

If he knew how it worked properley he would have backed off the bolt a 1/2 dozen turns and then lightly tapped the end of the bolt with a plastic mallet to bump the expander loose and we wouldn't be having this thread.

Go check down inside the steer tube first. Knowing how these can stick and knowing that the guy taking the stem out didn't know about how this stuff works I'll bet it's in there.

If he knew how it worked properley he would have backed off the bolt a 1/2 dozen turns and then lightly tapped the end of the bolt with a plastic mallet to bump the expander loose and we wouldn't be having this thread.

I had already checked the steer tube with a flashlight... nothing but caliper bolt. I just checked it again and re-re-rechecked every piece of bubble wrap and tape and foam in the shipping box, including under each flap of all the boxes. I shook the box and shook the bike. I really don't think it is there.

Oh well, it was a thought..... Back to the Vintage guys.....

What about the idea of making your own?

Oh well, it was a thought..... Back to the Vintage guys.....

What about the idea of making your own?

That worries me... I'll probably buy a new stem first. Dang this is a lot harder than I thought it would be.

I blasted out an email to a bunch of local shops known for their used bikes and got one that says they have expanders. I'm hoping!

Before you buy a new stem: note that old French stems are (often) 22.0 mm diameter, while most other stems are 22.2 mm diameter. It's not easy to find a 22.0 mm stem, but it's possible to sand the .2 mm off.

Yeah I read that on Sheldon's site... I'm a little confused because my stem has not been sanded but it is clearly marked 22.2mm (not that I look closer).