Looking at purchasing a new Jamis bike which employs the monocoque CF technique. Can someone explain the process and if it's that much better than non-monocoque CF frames?

Looking at purchasing a new Jamis bike which employs the monocoque CF technique. Can someone explain the process and if it's that much better than non-monocoque CF frames?

monocoque = all-in-one-piece

otherwise you have to build using lugs and glue or carbon welding.
as long as the frame is designed and constructed well, there should be
no issues. Look, Colnago and Time and others make frames with lugs,
many others build mono, like Kestrel, Felt(?), Trek, Cannondale, etc.

theoretically, with a monocoque design you can reduce the weight compared
to tube-&-lugs and adhesive, but in practice, complex shapes like the head
tube area and bottom bracket shell are complicated and expensive to fabricate.
for a monocoque design inflatable bladders are used to 'fill' the desired open
areas while the matrix cures. the major portions are usually 'layed-up' in high
precision molds and subjected to heat and high pressure. once the halves
of the frame are complete, they are lined up and wrapped with another layer
(or more) of carbon, bladders are inserted and cured again making the final
'closed' frame. the inflatable bladders are to compress('compact') the resin
and braided fibre matrix to squeeze out excess adhesive, to reduce weight.
this process is time consuming and labor intensive, especially when specific
lay-up schedules are required. this is one of the reasons why labor intensive
products move to where skilled labor is cheap(read: taiwan, china, india) - see
the aegis link.

newer techniques such as 'mitre, fit, wrap' and 'mitre, fit, weld'(either by induction
or by ultrasonic means) are also used by a number of other companies.

but rather than listen to me blather, here's some links from those who know:
(btw, i did not find anything about Jamis' construction techniques on their
website.)

http://en.wikipedia.org/wiki/Monocoque
http://www.aegisbicycles.com/about.html
http://calfeedesign.com/whitepaper1.htm
http://kestrel-usa.com/technology/production.php
http://www.colnagonews.com/en/tecnologia/ctb.php
http://www.time-sport.com/us/home.htm
http://www.velonews.com/tech/report/articles/10790.0.html
http://www.trekbikes.com/us/en/company/technology/oclv/

Thanks for the info!

Keep in mind that bicycle marketing folks like to use “monocoque” because it conjures up visions of speed, power and cutting-edge technology. Because advertising copy is written more to persuade than inform, the meaning of “monocoque” can be stretched until is has very little to do with its engineering definition. Unless you have insight into the frame-building process of a manufacturer, the term “monocoque” in their advertising copy doesn’t really tell you much. In some cases, the word is used to mislead.

I wouldn't worry about whether a cf bike is monocoque or not. If it rides well and feels good then buy it. As wim points out, its merely one of many processes used by manufacturers. Its no better or worse than any other process, it just sounds cooler.

riding a kestrel, perhaps the originator of the method, and riding a time, or colnago would be the way to see if you can differentiate between the two methods. I'd say the difference is negligable, and most people would never be able to tell the difference.

My lugged carbon feels slightly more plush to me than my monocoque frame. Whether that has to do with the lugs or not I have no idea. I have read that lugs can help absorb some vibration.

I've done a fair amount of research on CF processes used by numerous brands. I may have missed one, but I know of no manufacturer producing monocoque frames. There are various methods used that result in the appearance, but most first make subassemblies (main triangle, then seat/ chainstays), then align/ join using either epoxy (as in the case of Kestrel) or CF wrap. Some also start with internal lugs which are then CF wrapped - all variations resulting in a 'one piece' frame, but not really.

Does any of it really matter? The only thing I've ever read that seemed reasonable was that lugged construction (LOOK and Serotta to name two) is more ride tuneable (Flat Out's post seems to affirm it and he owns both).

Regarding Jamis as a brand, I'll share what I know because brands and their commitment to QC matters. Up to and including the '06 model year, Jamis had some manufacturing issues with their CF bikes. In '07 they changed manufactuer (Taiwanese - which the name escapes me at the moment) and their CF line improved noticably. I personally think their lower end CF bikes are a better value than the higher end - $1800 to $2500 range.

As for marketing hype, it's a given. The best example being little blobs of gel stuck inside tubes. Even if it does what they say, they call it Zertz? Sift through all the jargon and buy what's in synch with your abilities/ pririties/ finances and good luck to you!!

"Monocoque" is probably the most misused term regarding any bicycle frame. The term "monocoque" originally applied to aircraft construction wherein the external skin was the structural/load bearing component, rather than the skin being merely a "covering" over an internal skeleton - wood coming first followed by steel and aluminum tubing.

It then found it's way into race car construction, replacing an aluminum or fibreglass skin over a welded-up tubular chassis ( think Birdcage Maserati), starting with riveted aluminum and now carbon fibre.

In production cars it replaced the non-structural body on a ladder type frame (still used for most trucks and large SUV's.) It was generically called "unibody."

In that sense, virtually all bicycle frames are "monocoque", as none have an internal load bearing structure covered by a cosmetic or aerodynamic skin.

I would say that a lugged construction under a 'monocoque' frame would constitute a load bearing structure.

I would say that a lugged construction under a 'monocoque' frame would constitute a load bearing structure.

Not sure if you're saying this negates calling it a "monocoque." The "skin" is still load bearing.

If by "monocoque", the bike industry is referring to a frame in which the main triangle (i.e., the head, top, down, and seat tubes) is molded in one piece, as opposed to bonding together separate tubes (with lugs, internal or external, mitered, glued, etc.), then I give.

Call it a "monocoque.":D

Not asking you to 'give', your definition and examples of monocoque are inarguably correct.

I was merely saying that in one type of CF construction (lugs under the 'skin') some load bearing is internal.

If you disagree, we can call it NON monocoque, k?? :crazy:

If any of the main tubes are connected by lugs (internal or external) then, generally speaking, the "bike industry" would call it "non monocoque."

As earlier posters pointed out, good carbon frames come both "monocoque" and "non monocoque." And so do not-so-good-ones. There are far more factors in the equation.

All good info, but there's nothing like showing up for a Sun. morning club ride with a new bike and saying, "It's monocoque construction." It just sounds so cool to use words like that, especially when most of your friends aren't sure how to pronounce it. That's what cycling is all about...one-ups-manship. Yea baby! If you can't dazzle them with brilliance, baffle them with bs.