I saw a link to what appeared to be a Carbon bike on amazon. The price was extremely lower than any carbon bike I had ever seen. After reading a bit, it seems that the bike frame is really made of "carbon fibre wrapped aluminum". What advantages would wrapping an aluminum frame in carbon have compared to just a regular aluminum bike. Is it just to get a carbon look bike more cheaply, or does it allow you to use a narrower aluminum frame, with carbon taking up some stress, creating a frame with a weight somewhere between carbon and aluminum?
That is purely marketing. It's a common ploy with components, but I've never seen it on an entire frame until now. Aluminum and carbon can be used in conjunction effectively, but not in this case. The carbon wrap on that bike is basically veneer.
While Schwinn was once upon a time a well respected brand, they suffered a major fall from grace after going bankrupt. Their bikes, even their bike shop level bikes (i think they call them their "select" series bikes) target the budget market. They're not horrible, but they're not great either. The bike you posted a link to is no exception.
One could argue that the combination of dissimilar materials would aid to vibration dampening, but that's really just more marketing jargon, at least in this case. That bike will still ride just like a full aluminum framed bike would. If you are considering that bike save yourself a few bucks and just go with a full aluminum frame.
For the carbon fiber to be of any use structurally, it has have multiple layers. If it says it is wrapped around the aluminum, my bet it is for show only so it gives the appearance of being an expensive frame when it is clearly not.
There is no way that a composite of the two will be very light without being very weak if it were compared to a full Carbon frame or an Aluminum. Both materials will not hold up to a stress test. The Aluminum would be very brittle and the Carbon fiber would be very squishy.
Carbon and Aluminum are very light as is. Carbon fiber is light and when wrapped certain ways can be stiff or supple. Aluminum is always stiff, that is the nature of the material.
To reiterate, it is most likely a way to mask a cheap frame and pass it off as Carbon fiber.
It would in theory combine some of the characteristics of both, while permitting a cheaper bike than straight carbon. The aluminum could be thinner, providing only modest strength but serving as a mandrel to support the carbon, and the carbon would produce a stiffer bike than straight aluminum.
Or it could just be hype. Or the "carbon wrap" could be used to conceal crummy joining of the aluminum tubes.
Mid range bikes commonly have a carbon-wrapped seat post which claims to reduce vibration and increase comfort. Basically, get some of the benefits of a full carbon seat post with less of the cost. I expect this manufacturer is using the same concept on the entire frame to get carbon-like ride at a reduced cost.
Personally, I cannot discern the difference between a carbon-wrapped and a non-carbon wrapped seat post. I know other riders who believe it makes a difference (but they were using a different brand of seatpost).
I think it's difficult to tell if the carbon-wrap would improve the ride any just based on the description. I've ridden aluminum frame bikes that ride far better than full-carbon frame bikes that cost quite a bit more. The frame material is just one factor in ride quality and a "carbon wrapped" frame could be a huge improvement for the right frame design or a huge marketing gimmick for the wrong one.