Have a Schwinn Sierra not sure what year but it's got an odd handlebar stem. It's got a flex shock absorber as part of the stem assembly. It looks kind of like the trucks on a skateboard. I can't seem to find any reference to this type of assembly anywhere. The reason I'm concerned is because the bolt that goes through it has snapped apparently and I don't know how to replace it. I don't even know what this part is called.

Pre-MTB?
Need help . Mostly just info.. much appreciated

ZenTropi

You're talking about the screw going through the shock-absorbing "puck" on the front (as opposed to the pivot bolt)? Can you get the screw out, or is part of it still screwed into the main stem? Can you tilt up the stem to remove the puck and show us the nature/location of the break?

If you cant find a replacement bolt at the local hardware store, I encourage you to purchase a replacement stem- one that mirrors your current stem's angle and length. Just buy a fixed position stem, since there is no upside to using an adjustable angle stem.

I don't think it's an adjustable angle stem - it's a suspension stem - I don't think the main pivot is lockable to any specific set angle. That being said, I agree that, if the OP doesn't need a suspension stem, just buy a rigid replacement with the appropriate reach and rise.

Oh, I thought it was adjustable AND suspension. Like you could set the angle, and then tighten down the suspension bolt to 'lock' in the angle...while that pivot point also took a beating from the forward forces.
Interesting- its just a loose angle...which makes it seem like the forces against the step at that pivot would be even more than I figured.

Huh, wild historical tech.

Welcome! As others have suggested it's a suspension stem but an odd one. I've never seen that particular type before. Can you find a brand name on it? Flexstem and Softride are the most common ones (I've used both and still have a couple around) but that one is news to me. If it uses elastomers you can expect them to deteriorate and/or crack with age.

Found a stem that is similar--don't know if yours was made by Girvin, but here is one: Girvin Flexstem Elastomer Mtb Flex Suspension Stem Mountain Bike NOS 135mm 25.4 | eBay

If you look up the bike, when you find the same color bike, you'll have the year. Typically bikes come in one to three colors a year. The stem, however, was most likely added after the bike rolled off the line.