We thought hard about a Paketa. Two things dissuaded us. 1) our number one criteria was stiffness. Rightly or not, my thought was the ability to custom size the carbon tubes in the Calfee best served that criteria. 2) living on salt water, I was concerned about the paint and corrosion issues with magnesium.

If we lived inland, we might well have got a Paketa.

Magnesium stiffness is more like Aluminum, so not lacking in this measure I should think. Much more a factor of frame design. If climbing is an indicator of stiffness, Paketa rocks!
Hmmm. Probably defer to Dave Walker or others on this point. I followed the _heated_ thread a while back about a corroded frame and came away thinking that there wasn't much there technically, and customer support-wise they were doing the right thing. As buyer of competition, I would never bash Calfee or other builders, rather, think that we should encourage all the players in this field. I'm a sucker for posts describing custom builds from yet smaller shops: Quiring, Rodriquez, Landshark, etc. I only wish I could acquire one of each!

Though this thread was not initially about carbon -vs- magnesium, this was a conclusion that I lept to. It seems like the "conventional wisdom" is to go CF. I think Paketa is the only Mg bike maker out there. I'm not sure why this is. I would imagine that a metal tube frame bike must be less labor intensive than a CF layup. The material itself isn't terribly expensive and it is just a matter of cutting the tubes & welding them. Dave Walker once gave me a tour of his "factory". All else being equal, I would think that a custom made Mg bike should cost less than a custom made CF bike. However, I think the Paketa frame costs more than the Calfee frame (right?).

I think colotandem is one of the few who have owned both and likely has the rare perspective of riding both a lot. Most make the choice without ever having ridden both (like me).

I think the only way to really evaluate magnesium vs CF is to ride both which is pretty much impossible unless you travel to both Colorado and Santa Cruz, even then they may not have your size to demo. Looks like you live in Colorado so maybe you could and should demo a Paketa?
It does seem Paketa is the only builder of tandems or single bikes using magnesium. Pinarello used to make a magnesium version of the Dogma. I think the cost of making a custom frame from metal tubing whether it is steel, titanium or aluminum is underestimated. There is considerable cost in the materials and to make a good frame requires a high level of skill and experience. Custom frames made from metal cost in the the same range as CF frames made in molds in Taiwan. There are glaring differences in that CF frames in general have a much higher level of R&D, higher cost of production tooling, sophisticated assembly lines and high volumes compared to a one man shop with metal working tools, jigs and a welding torch. On a recent vacation to Santa Barbara, we ended up riding with a guy who was riding a custom Lighthouse frame made from Columbus tubing made in Santa Ynez, it looked really nice and he was raving about how good it was. I am pretty sure I wouldn't trade my Cannondale EVO for it, but if I had the money and could justify a second bike that might be it.

Well said. Carbon has a lot of advantages but the disadvantages are illustrated by looking at fork options. A custom steel fork can be had form a number of US makers with any rake, any crown race height, any brake setup plus with any cosmetic treatment desired. Of course the really big downside is that it will weigh multiple times its carbon competition.

I know of only one US carbon fork maker which has only limited offerings and is itself on the heavy side for a carbon fork. Others take advantage of economies of scale and are mass produced overseas with an extremely limited choice of geometry wheel size. Like a Cannondale EVO, you can get anything you want long as it is one of the limited number they make.

No, Di2 still requires that you decide when to change the front ring.

I'm not a big lover of disc brakes on a single road bike, but I would think they'd be pretty damn nice on a tandem. Shimano now has an Ultegra level Di2 hydraulic STI lever. A little blockier than standard Ultegra, but I rode with a guy that had them (on a single) in Park City and it looked like a nice setup.

I agree that homework is very important. We love our Calfee but Paketa is pretty cool too.

It may be obvious but a carbon fiber is probably the easiest to customize. The frame can be as strong, light, compliant, or rigid as you like. This means thinking hard about the intended use, geometry, fork type, Di2, wheel clearance, etc.

The less obvious point is that carbon fiber is easy to repair or modify (eg. straight to tapered head tube). Calfee and other CF builders can repair virtually any damage to a carbon frame. It's much more difficult to repair an aluminum or magnesium frame.

I'll chime in here at the risk of being flamed for being a Paketa owner.

We have in fact owned a Calfee Dragonfly and now own a coupled Paketa (and before the Calfee, we had a DaVinci). All bikes are pretty sweet. It would appear that Calfee has a stronghold on the high end tandem market (if you look at this forum). I think there are a lot of happy Paketa owners that are not joining these discussions, myself generally included. I don't have any desire to get in a pissing contest over my bike being better than your bike (this holds true for my previous Calfee, current Paketa or mtb tandems). There was a thread a while back about Paketa stiffness (I think) that got off the rails in my mind, since that time I don't really get into many of these threads.

Most of the small differences in one high end bike vs another, or one wheelset, or component group are so small that it is not worth the time to debate, b/c we all have OPINIONS. People tend to advocate for what they own. That is why there is a Porsche club and a Corvette club (or think Harleys and sport bikes) - never the two shall hang out together.

Having ridden both bikes, I REALLy like our Paketa. Can I point to the particulars of why? Not sure. Is it the frame? Is it the build? Is it the components? Is it b/c it's lighter? Maybe it's just because it is what I have NOW? But I am sure that I would buy another one if I needed a new bike for some reason.

If you get the chance to ride both, you should. Maybe go ride a Landshark, or an Eriksen while you're at it?

Sorry to take the Di2 & Discs thread further off topic...

The best part of all this is the fact that we can make choices… Rim /disc, CF/ Mag, Mech/ electric, paint / nude, Wide rims / narrow rims, drop/ bullhorns I am pretty sure you will have a nice ride whatever you choose.

Very much agree. I am REALLY glad the cycling community is not so tribal that we only ride with others of the same brand or even type of bike. We never get any grief about not belonging with our one of a kind 650B tandem from any other riders. It may be the opposite. I think some give us undeserved credit for being strong enough to ride such fat tires at anything like a normal speed.

Ride what you like and have fun.

I don't think anyone's bashing Paketa. For us, it came down to a choice of Paketa, Calfee, or Landshark. I don't think anyone of those would be a mistake.

I think you're right Merlin - all three of those are "drool worthy" machines - and was not implying that anyone in this particular thread is bashing Paketa. :)

Hey, why leave out the titanium bikes?

Seriously though, buying a tandem bike is like buying a nice car.
Every choice have their own advantages, disadvantages, and idiosyncrasies.
It would not be any fun if every one drives Porches, Mercedes. or BMW.

Pick one you like, have fun with the options, and enjoy.
CJ

I'll jump in also as a Paketeer, having just ticked over the 1,000 mile mark on our V2r (we received it end of April AND it has Di2 with hydraulic discs, to stay on topic). As said above, it all comes down to personal opinion, experience and aesthetics of what a bicycle "should" be. "It should be made out of some sort of metal", or carbon fiber, or corrugated paper or macaroni elbows from Italy.

The final product is both functional and aesthetic at the extreme, like furniture. More so than any other conveyance in my opinion. Motorcycles are a close second, but the simplicity of the bicycle strips everything down to the essentials. I've never heard of anyone slagging Di2 or discs on aesthetic grounds. Rather it's argued whether they're needed - heck, whether multiple gears or brakes are even needed. Then again, Harley Davidson took over 20 years to adopt ABS because they were afraid the tracking ring would ruin the look of their wheels!

I love the no-nonsense-industrial-utilitarian look of the Paketa frame and the ride quality is sublime. I think most Calfees are pretty, but that distinctive organic lashed joinery just doesn't do it for me. The buttressed lugs on his short bikes are more to my liking. I guess I like bikes to look like machines. The ride quality might lead me suppress such superficial qualms if I owned one, but the qualms would remain. And so, if I wanted a carbon tandem, I would likely choose a Landshark for no other reason than it wins out in the aesthetics department.

I'm positive I would not be able to say which one were "better", Calfee or 'Shark, if I had one of each built to the exact same specifications and geometry and rode them one after the other (I'll even throw in a 2-3 pound difference either way).

Back on topic: Di2 on a tandem is a no-brainer in my opinion. The advantages far far outweigh any perceived or real (are there any?) disadvantages. The lack of a triple option notwithstanding only because it will come to pass. The hydraulic discs are very nice, indeed. But for 90% of the time they are overkill. The stoker loves them on a peace-of-mind level. Her first experience with hydo-discs are the two pot Magura Gustavs on our Ventana. So that convinced her to spec discs on the Paketa. If it were just my decision I would have leaned more towards calipers (feigns weight concern). It had to be hydro though. Mechanical discs don't rate for much more of and advantage. Not enough overkill ;-)

Would you happen to have a picture online somewhere of your Paketa? I'm still gathering intel on which company my wife and I will go with to upgrade from our current Cannondale. I don't think I've seen a Paketa yet with front and rear disc brakes.

If comfortable ride is your highest priority, then I think Ti may still be a viable option. Although I don't know that a lot of people are still building Ti tandems.

If priority is stiffness and weight, then imho, CF easily trumps Ti.

For us stiffness is huge on the tandem. To make a Ti tandem, as stiff as an extrastiff Calfee, my bet is that it would weigh at least a pound more.

Merlin,

I would hate to see you on a tandem race.
In fact, I have given up on going fast on my tandem. My wife likes her ride leisurely. No aero tuck for her. These days, I take out the single if I want to go fast or with the single group.
So my coupled titanium tandem is specifically built for comfortable touring. Even so, the frame weighs less than 8lb. I am sure if you want, the builder could build you an extra light, non coupled version at a comparable weight and stiffness to your Calfee. But you would still not like it as much as you enjoy your Calfee now.
It is like comparing cars. We can argue all day on the virtue of a Porsche 911 versus a Model S. At the end of the day, we each are going to be more happy with the car we have already decided on.
CJ

I doubt you can build a titanium tandem both as light and stiff as a Calfee Extrastiff Dragonfly. Ti, while light is springy. To get a very stiff Ti tandem, you're going to have to use more Ti, which adds more weight,

Also give that CF is anisotropic, as opposed to Ti, which is isotrophic, and that you can dial in the layup of CF specifically to make it stiff where you want it, you simply can build a lighter frame for a given stiffness, or a stiffer frame for a given weight in Ti, than CF.

This is clear from single bikes. There are numerous 700 gram CF frames that are very stiff at the BB and head tube. The only Ti frame I'm aware of approaching that weight was a total noodle. In fact, I don't believe there's an off the rack Ti frame currently made that approaches the weight of the current lightweight standard bearers in CF.

The weight advantage of CF over Ti should only be more pronounced in a Tandem where the additional loads makes stiffness an even greater priority.

None of this is to say. You can't make a very nice tandem out Ti. If ride quality, durability, and aesthetics are the criteria I can easily see a well made Ti tandem.


But back to my point, if weight and stiffness are the criteria, Ti is not the material of choice.

This is all true but although some may prefer the feel or handling of a stiff frame I still haven't seen anything to prove that a stiff frame is faster.

Agreed that carbon fiber can be anisotropic. And in a single frame application where blown mold construction was used, the material can be layered, molded, and oriented to build a light weight and stiff bike.

But, that is not how yours was built. The way Calfee build their bikes, they can not make full use of the properties of carbon fiber. They are still round tubes glued at the joints.

Why is your extra-stiff version weighs heavier than the regular stiff version? They did not alter the application of the material, they just added to it. The extra stiff package got you more or larger tubing and maybe a few more layers of carbon fiber reinforcement. That is no different than a metal bike builder changing the tubing schedule to alter the stiffness and weight of their bike.

Until you do the double blinded placebo controlled study, or at least a head to head comparison, you really cannot over generalize. Even then you are only comparing the work of two builders.

But all that isn't that important. We all have different tastes. Some prefer the stiff suspension of a sport car, other the comfort of a sport sedan. If speed is an important criteria, either can be faster than the other given the appropriate engine. If enjoyment of the ride is the important criteria, than both will do well when paired with the appropriate driver.

^ Admittedly, a molded CF tandem frame would have advantages over tube construction. But you definitely can vary the charecteristics of the tubes with CF moreso than Ti.

"The metallurgical composition of a metal tube can’t be varied over the length of the tube. In contrast, composites can be infinitely varied over the length of the tube. Some of the variations include: different fiber angles, different plies, different ply thicknesses, and different combinations of materials. So the properties of the end product made from composites can be tailored to precise specifications. It is also easier to customize a composite tube for varying degrees of stiffness than it is to customize a metal tube. Additionally, the tooling cost for metal tube production is several orders higher than that of composite tube production. "

http://calfeedesign.com/tech-papers/...l-white-paper/

A number of custom builders are doing this quite sucessfully with tubed CF frames, such as Parlee, Crumpton, and Calfee. Crumpton builds a 690 gram single frame using a tubed approach

In addition to the ability to custom dial in stiffness exactly where you want it, there's simply that the stiffness to weight ratio gives CF a huge advanatage in building a light stiff frame:

http://www.calfeedesign.com/wp-conte...hitepaper1.gif

And those numbers would be even more exaggerated if you looked at the stiffness to weight ratio of the Dragonfly tubing, utlizing boron and high modulus carbon fiber in the layup.

There's still a case for Ti, but stiff and light isn't that case.

Looking at real world weights of bikes demonstrates that. A really good single Ti frame typically weighs around 1200 grams or more.(Litespeed Archon which is stiff for a Ti bike comes in at 1170; The current Merlin Extralight, designed to be stiff is 1400 grams.) Conversely, a number of CF frames that are quite stiff are at or below 700 grams, including the tube based Crumpton.

There's simply no reason to believe that this wouldn't carry over to Tandems given the basic nature of the 2 materials.

A Seven Axiom tandem weighs 7.7lbs. A Calfee Dragonfly weighs 6.25 lbs, and my bet is that a Landshark weighs even less.

And, having ridden Ti single bikes, I'm pretty sure the Axiom is not as stiff as either CF frame.

Now, none of this means the Seven, or any other Titanium tandem frame is a bad bike. And you can certainly make a rational decision that the extra pound and a half is worthwhile tradeoff for other advantages which may mean more to you.

I totally get you point, that different people like different things, and have different priorities. But I think you're fighting a losing battle in trying to maintain that you can make a Ti tandem frame that is both as light and as stiff as the current high end CF tandem frames.

I totally agree with that. I think the argument that stiffer is more efficient and faster is overblown, but that's a whole nother debate.

It may well be that people like the way Seven Tandems ride precisely because they are less stiff.

For us, given that a Co-Motion Robusta (which is a fairly stiff bike in it's own right) flexed enough that people would comment about how much the bike was flexing, and we occassionally had to back off in sprints due to the flex, stiffness was a high priority.

We really like the lack of any "stoker wag" and IMHO, that's the biggest benefit of a stiff tandem frame.

I like flexible bikes but we have to remember that stiffness is relative to the force being applied. We are a lighter and weaker team than merlin's so a stiffer frame may flex the same or more with their weight and power as a our frame flexes for us.

There is also some personal preference involved. I don't mind feeling a little more flex when standing or sprinting than some may like. Underlying it all however is the power in the motor. My feeling is that the stiffer is better mantra got its start because powerful riders have been able to flex any bike and have never ridden a really stiff frame like weaker riders have to deal with. Almost all builders are now or were in the past strong riders and often racers.

Merlin -

Interesting chart. Since the vertical axis is unitless there is no way to directly compare magnesium. However, I would imagine that the strength to weight ratio is about the same as the other metals.

It was explained to me that the reason that an aluminum frame can be lighter than a steel frame is that for the same weight of material, aluminum tubes can have a larger diameter without the tube wall becoming impractically thin. Larger diameter tubing leads to a higher area moment of inertia which increases bending strength. To achieve a large diameter tube with the same weight in steel, the wall would be so thin that it would dent with light pressure. I assume that since Mg has a lower density than Al, this holds even more for Mg.

This leads me to another (maybe not original) idea: If a metal tubing bike frame could be welded up airtight, the frame could be pressurized much like a soda can and the tubing wall thickness would be less of an issue. The danger would be that if it ever lost pressure, the whole frame would collapse in an instant (think of standing on an empty soda can). Maybe OK for a test bike but too much liability for a consumer item.

Merlin,
You are just repeating promotional materials supplied by carbon fiber builders.
Show me some independent studies comparing the various materials used on tandem frames.
Someone from Paketa, Seven, or Comotion can make any claim they want regarding their materials.
Until someone else verify, it is just promotional material.

Be objective in your observation. If you look at the your frame in nude form, there is not much that they can control beside the joints and the tubing schedule. Their promotional material also conveniently ignore the double and triple butted metal tubes.

Someone posted a Fairwheel study previously on crankset stiffness. By virtue of the carbon fiber material used, the lightning cranks should be extra-stiff. But it came in next to last. Behind the DA metal cranks. So it is not only the material but also what you do with it. But what does this really mean? Is stiffer better or worse? Since stiffness is your biggest concern; why did this not stop you from using the carbon fiber Lightning cranks? Is it because carbon is always better than metal?

My frame weighs less than 8lb with 4x2in. S&S couplers. Without the 2lb worth of couplers, it is about the same weight as yours.

I am not saying that it is better or worse. Just don't jump to conclusion too quickly without a fair objective comparison.