# lugged carbon



## PoorCyclist (Oct 14, 2010)

Does a lugged carbon frame mean the frame is a lower quality construction?
Are there any advantages lugged carbon offer over a mono frame?

I only saw the lugs from seatstay to chainstay, where are the other lugs?


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## Dave Hickey (Jan 27, 2002)

Certainly not lower quality....Here are some examples of lugged carbon frames

http://www.calfeedesign.com/dragonfly.htm

http://www.crumptoncycles.com/superlight_carbonframes.html

http://www.parleecycles.com/z5/


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## latman (Apr 24, 2004)

You can have a monocoque front triangle with the stays externally "lugged", they can also be internally lugged then "wrapped" with carbon fibre and sanded/sprayed to "hide" the joint


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## laffeaux (Dec 12, 2001)

Dave Hickey said:


> Certainly not lower quality....Here are some examples of lugged carbon frames


Here's another lugged carbon frame that looks really neat and is certainly not low end.

http://www.ifbikes.com/OurBikes/Road/Corvid/


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## PoorCyclist (Oct 14, 2010)

I saw a CX frame with lugs and want to know if the lugs are supposed to help with the rugged environment for CX.


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## ewitz (Sep 11, 2002)

...and many others


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## Dave Hickey (Jan 27, 2002)

And many people think this is monocoque but it's lugged too...they are internal lugs.


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## DaveT (Feb 12, 2004)

As well as Serotta:


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## serious (May 2, 2006)

PoorCyclist: *I saw a CX frame with lugs and want to know if the lugs are supposed to help with the rugged environment for CX.*

Not at all. Overall construction (CF type, layout schedule, tube shape, etc) dictate what terrain is appropriate. Lugged construction is simply a bonding method for non-monocoque frames.


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## Gimme Shoulder (Feb 10, 2004)

PoorCyclist said:


> Does a lugged carbon frame mean the frame is a lower quality construction?


I have no first hand knowledge of Independent Fabrication, but they they seem to be very well regarded. They sure make purdy (and purdy damned expensive) lugged carbon frames. The XS is carbon tubes with Titanium lugs. The Corvid is carbon tubes and carbon lugs.

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## Mike T. (Feb 3, 2004)

PoorCyclist said:


> Does a lugged carbon frame mean the frame is a lower quality construction?


Ask Mr Colnago that question.


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## JacksonDodge (Mar 26, 2006)

Dave Hickey said:


> Certainly not lower quality....Here are some examples of lugged carbon frames
> 
> 
> 
> http://www.parleecycles.com/z5/


The Z5 isn't a lugged frame.


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## moonmoth (Nov 8, 2008)

Seeing these lugged carbon frames makes me wonder why the smaller craft builders (that I've seen, anyway) aren't offering carbon frames in addition to steel, aluminum, and Ti.


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## DaveT (Feb 12, 2004)

moonmoth said:


> Seeing these lugged carbon frames makes me wonder why the smaller craft builders (that I've seen, anyway) aren't offering carbon frames in addition to steel, aluminum, and Ti.


Some are; Carl Strong, John Slawta among others though it requires a different skill set. Some guys are busy enough with their normal orders. See here, Nic Crumpton's review of his carbon build process: http://www.velocipedesalon.com/forum/f26/carbon-building-18058.html


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## Ride-Fly (Mar 27, 2002)

Dave Hickey said:


> Certainly not lower quality....Here are some examples of lugged carbon frames
> 
> http://www.calfeedesign.com/dragonfly.htm
> 
> ...


I am almost certain Crumpton frames are tube to tube. I don't know about the Z5, although the other Parlees (Z1, Z2, Z3) are tube to tube as well. I agree lugged carbon frames are not lower quality. If anything, they are generally higher quality.


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## Gnarly 928 (Nov 19, 2005)

I have an opinion. 

Lugged carbon frames are not taking full advantage of the engineering advantages of carbon fiber as a material. 

They are a hold over from the days when you could only get tubes of metal to build from. So at every junction of a metal frame, you had to end the tube and start with another...some frames did that with welds, some used brazed and cast lugs at those junctions. But carbon fiber can be shaped and given strength any way an engineer decides might work best for the characteristics he wants from the bike frame..or the wing or the F-1 Chassis..whatever.

So engineers don't make sheets of carbon fiber and then rivet them together for airplanes, they don't take hundreds of small tubes and stick em together for 'space frame Formula One chassis, we don't make 'planks' of carbon fiber and then screw them onto carbon frames to build boats... ..They decide the load paths and how much fabric needs to be in there to make the frame do it and they shape it to best carry the loads. They run the fibers right around the junctions, with no interuption, no lug, no joint, no "hard spot" or fatigue point.

The one advantage of a lugged carbon frame is they can make many different sizes, use just a few sizes of lugs and come up with a wide size variety of bikes at cheaper cost. Bike builders are slow to change..."We always use lugs"...even though there is no real reason to make a carbon bike like that (at least no body has ever come out with one,) other than you can fudge the geometry around without building a bunch of different molds or having to pay a skilled work force that can produce good tube to tube joint consistently in carbon fiber.

OK, now I have to duck, because people really really are militant about *their* particular lugged carbon frames...


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## Fai Mao (Nov 3, 2008)

I doubt it would indicate quality at all. It might indicate that the OEM guys have figured out that small-medium-large size really doesn't fit everyone and a lugged approach could be a way to gain access to a greater variety of frame sizing and gemometry without requiring a new set of molds. The molds for monocot frames expensive and it might lower production cost to actually be able to use a lugged approach. If that is the case it is actually GOOD news 

Early carbon frames like the Specialized Epic were carbon tubes screwed and glued into aluminum lugs. They rode really nice but had problems similar to the old Vitus 979's because the adhesive would sometimes fail and the bike would literally come apart. However, I think that issue has been solved over the years. . 

It could also be simply a nod to classic bike design. 

Those are actually pretty frame pictured above. I'd kind of like to have one. Most carbon bike are uglier than ugly. I have a carbon Triathlon bike that I bought a while ago. I might should see if I can crash it and get a new frame that looks like a bike and not a part of a UFO


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## ciclisto (Nov 8, 2005)

I would agree that a mono layup allows specific placement of the carbon and any shaping desired.. but they are expensive and then most only have so many sizes.. Colnago uses lugged tubes and are very successful and the EPS the top of the line is still done up this way. Now the CX-1 is mono and according to Gnarly is a great frame ... I too have a lugged C-50 and would not part with it and I am looking for a CX-1 also.. no concerns.
I think beside tradition Colnago and others like the custom size available i.e. short top tube extra long seat tube etc. and many sizes. Curious if Gnarly has tried the EPS and his comparison to the CX-1 It seems to me and Colnago both work.


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## gearguywb (Dec 26, 2006)

Crumpton is tube to tube construction


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## latman (Apr 24, 2004)

Tube to tube wrapping is a very light/nice way to join carbon tubes that cannot be welded , it is very labour intensive to get a nice finish (sanding) which is why China(low wages) is the source of so many of these bikes .Lugging is heavier indeed and puts a stress riser at the end of each lug, but that appears to not be an issue . There is much more "control" when making each tube individually rather than an internal bladder and more variation in pressure and wall thickness of monocoques. I think the weight limits of durable frames have been found at about 900grams ,I personally think 1kg (2.2lb) is the go for my preferred 56 -57 cm need.


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## Dave Hickey (Jan 27, 2002)

Ride-Fly said:


> I am almost certain Crumpton frames are tube to tube. I don't know about the Z5, although the other Parlees (Z1, Z2, Z3) are tube to tube as well. I agree lugged carbon frames are not lower quality. If anything, they are generally higher quality.



My bad...I agree they are tube to tube and not lugged.. much like lugged vs Tig welded steel....but they certainly are not monocoque


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## moonmoth (Nov 8, 2008)

Given all of the CF frame cracks that you read about here and other places, wouldn't a lugged CF frame be easier to repair than a mono one-piece frame? And be able to be repaired by more than just a handful of specialists now, like Calfee?


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## rx-79g (Sep 14, 2010)

Gnarly 928 said:


> I have an opinion.
> 
> Lugged carbon frames are not taking full advantage of the engineering advantages of carbon fiber as a material.
> 
> ...


Lugged or tube to tube construction accomplish the goal of using material only where it is needed. The tubes used in that kind of construction are straight gauge with thicknesses optimized for the span, not the joints. The lug or overwrap do exactly the same thing as a butt or the thicker parts of a monocoque - add material in the higher stress areas that both connect the tubes and reinforce them.

Round tubes are still as effecient a shape for bicycles as any other. That is why tube to tube lugged or overwrap can yield frames that are competitive with molded frames for weight and ride, yet are costumizable and appealling to those who like a more classic aesthetic.

http://www.bgcycles.com/customgallery.html


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## Hank Stamper (Sep 9, 2009)

Once you get beyond all the BS I don't think it matters one way or the other. Someone could be a great frame and someone could make garbage with either method of construction.


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## DaveT (Feb 12, 2004)

Hank Stamper said:


> Once you get beyond all the BS I don't think it matters one way or the other. Someone could be a great frame and someone could make garbage with either method of construction.


<gets it>


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## Richard (Feb 17, 2006)

Hank Stamper said:


> Once you get beyond all the BS I don't think it matters one way or the other. Someone could be a great frame and someone could make garbage with either method of construction.


Exactly. The "advantage" of tube-to-tube and/or lugged construction is the ability to customize the sizing and geometry.

The fact that both the Colnago C-50 (lugged) and the CX-1 (monocoque) get pretty much rave reviews says a lot.

By the way, "monocoque" is somewhat of a misnomer. From aircraft and automotive applications, it means the "body shell" is load bearing without necessarily having internal reinforcing elements. From that, even a lugged steel frame is a "monocoque."

In the bicycle world, it simply means that the main triangle was made in one piece.


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## Quattro_Assi_07 (Jan 13, 2006)

*My one and only carbon bike...*

...has lugs and is not a frame of lower quality construction. 



















It will soon be joined by its carbon cross kin, the CX01. :thumbsup:


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## maximum7 (Apr 24, 2008)

I was always under the impression that lugging was a more expensive process. 
The way the carbon had to be laid up and then the high pressures that they were subjected to, to make a strong juncture..and that this process had to be done by hand. 

I also thought that you could tune the ride a lot more using lugs.


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## rx-79g (Sep 14, 2010)

maximum7 said:


> I was always under the impression that lugging was a more expensive process.
> The way the carbon had to be laid up and then the high pressures that they were subjected to, to make a strong juncture..and that this process had to be done by hand.
> 
> I also thought that you could tune the ride a lot more using lugs.


It is a more expensive process because it involves two sets of lay ups - the tubes, then what connects them. But really, all the carbon tubing needed to make one frame is a few hundred dollars. So the mitering and joint construction takes some labor, but it is labor that can be acccomplished with lower tooling costs than a shaped carbon frame.

The pressures are actually not that high. Vacuum bagging uses atmospheric pressure, which is going to be 14 psi or less. Electrical tape raps also produce an appropriate amount of pressure. Higher pressures force the epoxy out and that sparsity leads to a weak join.

For lugs, the proper bond line is .006" to .012", which is a pretty decent gap for the epoxy to fill.


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## maximum7 (Apr 24, 2008)

I suggest watching this video.

Look says the BB lug on it's 585 are compressed to 3600 psi and the other lugs are 360psi


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## Fai Mao (Nov 3, 2008)

maximum7 said:


> I was always under the impression that lugging was a more expensive process.
> The way the carbon had to be laid up and then the high pressures that they were subjected to, to make a strong juncture..and that this process had to be done by hand.
> 
> I also thought that you could tune the ride a lot more using lugs.



I would doubt that there is any hand work done on a monocot frame other than maybe taking it out of the mold. I think the process is completely automated


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## kbwh (May 28, 2010)

From 1:30. Looks like some handwork is needed on a non-lugged frame too:






But lugged carbon is oh so fine.


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## rx-79g (Sep 14, 2010)

maximum7 said:


> I suggest watching this video.
> 
> Look says the BB lug on it's 585 are compressed to 3600 psi and the other lugs are 360psi


My bad. I should have said "the pressures needed to form carbon aren't necessarily high, and with liquid epoxies can't be". Prepreg can go higher because epoxy flow isn't a problem, but they don't need to go higher - Look does that to make the surface uniform, not to make the lug strong enough.

Also, it is one thing to say "3600 psi", and another to know how that force is applied. Vaccuum bagging applies its meager pressure in all directions, while die forming involves a press and one direction. With a die the 3600psi is what is applied to the die, but not what would be uniformly measured on the carbon. The difference between standing on a sealed can and taking it 100 feet underwater. It may also be a question the kind of bonding agent being used - they might be using the pressure in leiu of direct heating.

Anyway, my point was simply that high pressures aren't a necessity to carbon construction. Excellent lamination can be had with somewhat trivial, uniform pressures. I would bet that Look's tubes are not bonded under much pressure, for instance.


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## Fai Mao (Nov 3, 2008)

I find a certan humor in a bike that says "Made in Italy" all over it equipped with Shimano componants. At least it is Italian Japanese and Durrra Ahhhce (Sounds kind of like Veloce)

But your point is well taken. But I don't know if Trek making 1,000,000,000 OCLV frames a years has that much handwork in their monocot frames though.


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