Before Carbon Fiber There Was... Plastic?
 

Craziest looking bike I've seen in a long time showed-up on my local Craigslist...

https://milwaukee.craigslist.org/bik...115272850.html

I wonder if it's recyclable? :foo:

https://cimg3.ibsrv.net/gimg/bikefor...a2734d5df9.jpg

But in actuality CF bikes are plastic bikes too. They are just carbon fiber reinforced plastic resin. I know bike mfg that make a huge profit on their plastic bike would probably like to put out a hit on me, but it is the truth.

I think I saw a recycled cardboard bike on the web once, was pretty goofy.

And steel is just iron with carbon and alloy bikes are just aluminum with magnesium and other elements. Carbon Fiber is Carbon Fiber with some resin to bind it together., It isn't reinforced plastic. These materials are far superior to their base material. You wouldn't make bike from iron, pure aluminum or plastic. So what's your point?

That is an awesome find. To see how they engineered it with reinforcing ribs to add strength to the plastic. I wonder how much it weighs. Goes to show what a superior material composite/CF is over plastic.

Kinda interesting has drop bars on it. Last bike I'd think about aero or headwinds on.
Specialized sees it they have a new gravel bike

Wow that’s different
 

Crazy looking

Itera plastic bicycle - A failure after 3 years. First introduced 1981. Swedish. Weight - 49lbs.

"This bicycle has been described as heavy, flexible, and fragile, and is considered one of the worst bikes ever made!"

But - you'd have something much closer to a bike with just the resin, no carbon fiber than if you left out the resin. There was good reason fiberglass was called GRP (glass reinforced plastic or FRP (fiber reinforced plastic).

This from someone who has built ~50 frp boats, one with carbon fiber. It's just another fiber you have to lay out in a mold, wet out and cure. Yes, the wetout now is prepreg and the laying out is done in a dry state, molds are usually closed and the end result oven heated but overall, fundamentally the same. Workmanship is just as important but now no no one can see it, not the customer and often not even the supervisor.

Carbon fiber is a much bigger jump from the bare fibers than any metal form its raw element. You could make and ride an iron bicycle just fine, It might weigh 100 pounds but it would work, Same with raw aluminum or titanium. That bag of fabric will never get you anywhere.

Somehow I don't think the amount of resin in a CF would be enough to make anything close to a usable bike - just took at what it took to add enough strength to the plastic bike posted here. IMO it is clear that the CF is what makes the material, not the resin.

Such a bicycle may literally have been manufactured. There was a bicycle in the 1890s called the Lu-Mi-Num, the frame being a one-piece casting, and it's likely that the metal used was pure aluminum.

It's a composite. The combination of the materials makes the material.

The amount of resin in a CF bike wouldn't be enough to make a viable frame, because it's not reinforced. But if you used a lot more resin, it can be done as long as we don't end up volume-limited. The same cannot be said for carbon fiber, which by itself is just threads: even if you had boatloads of carbon fiber fabric, it's difficult to imagine how you'd create a usable bicycle frame out of it. This is why what we're calling "carbon fiber" is often referred to as "carbon fiber reinforced polymer", not as "polymer-bonded carbon fiber."

The drop bars are kind of a head-scratcher, especially given that it appears to be a single speed. They look to be newer than the rest of the bike, do make of that what you will.
I would have expected a coaster brake, but maybe the frame isn’t strong enough there.

Looks like the kind of bike you’d buy a bunch of for a lake/ beach resort that you can just leave around outside. (Solid tires, too)


Scott and YETI produced some plastic-framed MTBs in the 90’s, when CF was still too brittle for trail use. (They tried a lot of strange things in the 90’s)

https://cimg4.ibsrv.net/gimg/bikefor...6c8db605fe.jpg

Then, there's always this...
https://cimg8.ibsrv.net/gimg/bikefor...b19e81d950.jpg

Anybody remember the Kirk Precision cast magnesium bicycle?
https://mariposabicycles.ca/wp-conte...kirk_03355.jpg

His point was tongue-in-cheek, referring to the fact that what we commonly refer to as just "carbon fiber" is known technically as carbon fiber reinforced plastic.

That would have been just after the technique of separating aluminum using electricity was industrialized, where until that time aluminum was more valuable than gold.

It probably wouldn't have been lost on the producers of that bike that right up till then the public would have looked at an all-aluminum bike as literally a bike made for a king. Oh how times change. :-)

Found this for you all...


https://cimg2.ibsrv.net/gimg/bikefor...9979d04a3.jpeg

But it is CF reinforced plastic resin. Just like fiber glass reinforced plastic.

That’s kind of a gross oversimplification.

CF typically uses a catalyzed resin binder, as opposed to the thermoplastic in a typical FRP part.
This is why CF parts are lighter and stiffer than ‘plastic’ but relatively brittle. They’re good for where you would use a tube or monocoque structure, and where impact resistance isn’t a priority.

FRP is generally denser (read heavier) but tougher, particularly impact resistance and compression. I’ve seen it used a lot in applications where you might otherwise see an aluminum or magnesium casting.

Yeah, carbon is the softest element in the a Universe. Especially in that really clear form that brides tend to favor over the version that husbands prefer in the bbq. It’s all about how you use it, and how it is prepared. I’d love to see a raw iron bike. No prep, no smelting, no heating. Just a raw iron bike. Can’t wait.

See also, "harsh ride". Those wheels are almost identical to a great many wheelchair wheels (I worked in a wheelchair shop for 12 yrs). Nearly impossible to break, but give the ride comfort of cast iron. And yes, they're FRP, which is why they don't break. You could bend them, though, which makes me wonder how badly that frame flexed. And it looks like even the crankarms are FRP, which couldn't have been good at all.

If the OP's example were in pristine condition it might have some collectible value. As it is, it's not restorable; it'd be a flat-out miracle to find an OEM handlebar for it.

Plastic is an extremely generic name, sometimes called “polymers” or “resins”. The name plastics is usually reserved for cheaper consumer goods That are recyclable, but it’s a blurred line. The resins for bike frames used are a thermoset type which cannot be recycled. Their are literally millions of formulations and as different as flavors of soup. (Polymer) Soup is actually a great analogy.

The role of the resins is to protect the fibers and transfer the loads to the fibers. The resins themselves are relatively weak but in a liquid processing state wet out the fibers for a strong bond. The fibers have the majority of the attractive engineering properties we want. Carbon fibers being the most common for their high tensile properties and strength to weight ratio. The continuous fiber strands are also key, short fibers don’t have the aspect ratio to take advantage of the material properties for high structural applications.

The design and manufacture of these fiber-resin Composites is high level engineering stuff, essentially Aerospace level. These are not simple boat hulls. The directionality of the layers (lamina) are highly controlled and specifically designed for your strength and flex in different locations on your bike frame. A LOT can go wrong, which is why I would never trust a cheap no-name brand. These things are expensive for a reason And quality matters. Joe’s auto repair shop can’t just weld one or fabricate one up.

I got my Engineering degree in composites. I fondly recall Laminate Analysis being one of the most difficult classes ever as computers back in the early 90s weren’t what they are today for analysis. Yes, I calculated things by hand involving large matrices mathematics that still gives me nightmares 25 years later. Today’s computers handle the analysis much better... god bless technology. But computers don’t make the design decisions. Quality manufacturing has come a long way too.

The Itera is a major collectors item. If you have space and time in your life for a famous oddity buy this bike now.

In actuality this would seem to be an outstanding way to make a bike frame that is not that expensive. Once you have the mold, one fast high pressure injection, and you have a strong light frame. BTW notice how clean it is with its down tube shifters and the brake cable wrapped to the handle bars. No cables flapping in the wind.