What metals?
 

I have a Schwinn Crisscross, like this: http://www.bikehounds.ca/wp-content/...3482-Large.jpg

via google, I found out that the frame is probably aluminum. But, what are the seat post and stem made out of?

I ask, because my bike is rusting and it needs some work. I'm trying to decide between bluing/blacking, auto painting, or electroplating (if I can make electroplating affordable!) in various areas.
But, I need to know what kinds of metals they are to make those decisions.

Thanks for your help!

Aluminum doesn't rust, but steel will if precautions aren't made.

Googled up a manual on the bike for ya- http://bikecatalogs.org/SCHWINN/MODELS/Crisscross.html

Sorry, Corrosion on the aluminum. Thanks for correcting me.

The manual says that my bike has an aluminum frame, and it was nice to have that verified.

I'm still looking for into on the stem and seat post. :thumb:

If a magnet sticks to the stem and seat post, then they're steel.

If a magnet doesn't stick, it's aluminum.

If your bike is like the one in the link, it's not aluminum. The bike you pictured has a lugged frame. Aluminum is rarely used in lugged frames and certainly not in low end frames made by Schwinn. Further, corrosion of aluminum doesn't look like "rust". It's not red but white.

The parts on the frame...seatpost, stem, crank, hubs, rims, etc...are mostly aluminum. You really shouldn't have to worry too much about those. Aluminum is a reactive metal but it oxidizes almost instantly and forms a protective layer that is much tougher than the aluminum.

You can find all kinds of information on protecting frames on the Internet. Surly provides this. There's lots more out there.

If it's EXACTLY like pic in OP, then it has a steel frame, an aluminum seatpost and steel stem.

I wouldn't go nuts with paint or plating on that bike, just wash and wax. I spritz WD40 in bolt heads on occasion to keep them from rusting. Clean and grease the inside of the seattube and the seatpost, same with steerer/stem. I get a lot of old bikes with rusted bars and stems come into my work and frequently remove grips/shifters/brake levers, separate bar and stem, quick sand, wipe with alcohol and hit them with flat black primer and that improves the looks of the cockpit fairly easily.

I'll sometimes do that with thrashed black seatposts, also. Sometimes WD40 and 0000 steel wool on seatposts and bars if they're chromed.

Pic of actual bike and I could tell you what I'd do with it to spruce it up.

Since it's enough of a concern for you to have asked, I'd try the magnet test on the main frame tubes too. Then you'll know for sure.

I'm going to disagree with cyccommute about lugged aluminum frames. There was a window of time in which aluminum frames were commonly produced, even at the low end, by bonding the tubes into metal lugs. My Raleigh Technium frame is one of those. Your Schwinn might be one too.

I don't think Schwinn did much if any in the glued aluminum arena.

I think the CrissCross in the photo is a 1991 and they had DB CrMo main tubes and fork, with presumably HiTen stays.

The bonded frames usually consisted of a tube over a socket...look at the Raleigh Technium frame as the prime example...that was bonded in place. Steel lugs are tubes placed in the socket and brazed into place. If you fit an aluminum tube into the lug like a traditional steel frame, the lug would have to be huge to be strong enough. A steel lug has a wall that is about 1/8" thick. Aluminum, with a third of the strength of steel would have to be proportionally thicker leading to walls that are 3/8" to 1/4" thick. Even I would have to admitt that the lugs would be ugly...and I like the look of aluminum tubes. Even the glued aluminum frame lugs were less than pretty.

I also agree with LesterofPuppets. I don't recall ever seeing a glued aluminum Schwinn.

cyccommute doesn't like it when people disagree with him.

Classy. Don't address the issue, attack the person.

Did Schwinn ever make a bonded aluminum frame? The only bonded aluminum frames that I know of are the Raleigh Techninums that you referenced and Alan frames. If you look at the picture linked to by icor, it's pretty clear that the bike is a steel frame. no1mad linked to a catalog that clearly indicates the bike is steel. You made a mistake, got corrected, move on.

Hi,

The manual says the frame is chrome-moly, not aluminium.

Is is clearly a steel frame, steel stem, seatpost looks aluminium.

rgds, sreten.

It's absolutely a steel frame.

Just a note, that not all steel will cause a magnet to adhere.

So the 'magnet test' is not conclusive--though it has good probability.

If the magnet sticks it is steel. If it doesn't then it probably (which is not the same as certainly) isn't.


Also try the 'test' in a couple of locations, since bikes repaired with bondo type substances will not have the magnet stick in repaired areas.

I thought the lugged aluminium bikes used traditional steel lugs with aluminium tubes? If so, the lugs wouldn't have to be any thicker than traditional steel tube lugs (and the lugs I have seen were much thinner than 1/8")