merlinextraligh

Starting to get the itch for a new tandem. (Our Co-Motion Robusta is going into it's 6th season and has around 25,000 miles). I like the idea of getting a bike 3-4lbs lighter, but admittedly most of the reason to buy a new tandem is just to have a new toy.

The bike will be used mostly for training and fast group rides, and we'll race it a few times a year. (State time trial championship, Masters Nationals).

My concern with the Paketa, and to a lessor degree the Calfee is frame stiffness. We got the Robusta, instead of a Macciato specifically because we wanted a stiffer frame. (Team weight 340lbs).

The Robusta is acceptably stiff. However people riding behind us say they see noticeable flex in the rear end when they're following us at speed, and a couple of times there's been enough frame flex to bother me to the point of slowing down. (However, those were both extreme circumstance, standing sprinting in the high 30's, attacking downhill, pedaling a high rpm in the 50's).

So we need to new bike to be at least as lateraly rigid as the Robusta, preferably moreso. The open frame design of both the Calfee and the Paketa concern me in that regard. My thought is the Calfee can be built, perhaps with some modification to address the issue. I'm concerned that we'd find the Paketa too whippy.

Thoughts? Experiences?

waynesulak

I can only be envious of the power you put out flexing a Robusta at speed and look forward to the responses from large/powerful teams. The few Pateka and Calfees I have seen had teams that looked under our 280 lbs.

colotandem

Funny, I was thinking the same thing about flexing the Robusta. I'll be interested to hear the responses on this one.

I won't attempt to describe lateral stiffness of either bike. We are about 270 lbs and just don't generate the power that would likely influence lateral flex like you described. We have ridden both Calfee (several thousand miles) and Paketa just for a couple of test rides. We are big fans of both bikes. I will also add that our new Paketa is currently being built! I'll be happy to share any insights after putting some miles on it this spring.

merlinextraligh

Our raw power is pretty good. The w/kg not so much.

dfcas

When I was at Calfee a few years back Craig said at our team weight he would built up the stiffness somewhat from the normal level. I have no doubt Calfee can build your frame as stiff as you like. No experience with Paketa.

merlinextraligh

That fact has me leaning Calfee. I'm pretty sure it's pretty much a matter of the right layup to meet our desired riding charecteristics. Mind telling us your team wieght?

For the Paketa, I read their literature regrding stiffness, that the Paketa is "more efficient" than a stiff chrome moly frame:

We’ve compared the Paketa compact geometry to several other designs. One of the comparisons I made early on was against a conventional cromoly steel tandem frame with a lateral tube—one that scored highly in a Santana Tandems comparison test published in their catalog several years ago. Compared to the cromoly frame, the Paketa compact frame recorded about 1/3 less deflection in the front triangle, nearly identical deflection in the stoker compartment, slightly more deflection in the rear triangle…and weighs slightly less than one half as much as the cromoly frame. So, by my own “efficiency index” (a concept promoted by Santana) if you add up the three stiffness numbers and divide by the frame weight, the compact-geometry Paketa is more than twice as high as the cromoly frame and at least as high as any other tandem on the market today. What separates the Paketa from all the others is the ride quality, which is unequaled due to the special properties of magnesium.

The slight more deflection in the rear triangle concerns me.

dfcas

360 lbs. I know that he has heavy tubes to choose from, and further they can overwrap joints to stiffen up a given frame. I was surprised at the lack of a production line per say. I have a Luna pro single, and even those are made only after looking at the riders weight. So not custom per se, a Luna may be built up or down in stiffness, with a longer or shorter headtube or seat tube. There is no production line. Each frame is built one at a time.

akexpress 

We weigh at about 340 also. My wife stoker is a very fit strong rider whom can definitely put the power to the pedals. When Calfee built our frame they utilized our weights to optimize the ride for us. We did not need a custom size but they taylor each frame to the riders. We can both stand and put the power to it and it doesn't have noticeable flex but still has a supple ride. There was a thread sometime about Bill McCready at an event with a tool to measure lateral deflection under load at the bottom brackets and I believe the Calfee tested had the least deflection. Not sure how that correlates to the ride feel but it was a quantitative value none the less. It is also possible with a Calfee to alter it after the fact if needed. They have been great to work with for us.

Dean V

Also consider that if you are time trialing a large tubed stiff and light frame may not be as fast as a smaller tubed heavier frame.

Ritterview

Isn't it about time Santana released some of the frame stiffness data it has compiled using its device? This from March 2010. Was discussed last year, as well.





In a Calfee Dragonfly, boom tube deflection of 15.03 mm. What is the measurement for a Paketa? Surely Bill McCready has measured a Paketa too.

waynesulak

A agree. Too bad Bill didn't agree to provide the participants with the results of his little study.

I do think there is a difference between rear triangle, main tube and fork deflection. They should feel differently and have a different effect on power transfer and handling.

While it appears Santana's machine measured a composite of all of them the results would make interesting reading.

jnbrown

I did not notice any reduction in stiffness going from an aluminum Santana Sovereign to the Calfee.
If anything the Calfee feels better when we are standing on climbs.
Our team weight is 250lbs and we don't put out a lot of power.
We did loose about 6 lbs in weight going to the Calfee but a good part of that was in the components.
What I notice much more than the weight loss is a much smoother ride which is not only more comfortable but allows higher speeds on rough roads.
As others have noted I am sure Calfee can make the frame as stiff as it needs to be for your liking but it may cost a bit more than a standard build.

Ritterview

The upcoming NAHBS would be the place to really look over all the tandems, and ask questions about things like frame stiffness. From the list of exhibitors:

BILENKY CYCLE WORKS
CALFEE DESIGN BOOTH: #728
CO-MOTION CYCLESNAHBS BOOTH: #417
DA VINCI DESIGNS BOOTH: #1117
ENGLISH CYCLES BOOTH: #705 & 707
KENT ERIKSEN CYCLESBOOTH: #423
PAKETA MAGNESIUM BIKES BOOTH: #441 & 443
RITCHEY DESIGN BOOTH: #933 & 935
SANTANA CYCLES, INC BOOTH: #1204 & 1206




Cyfac tandems allow options for greater stiffness. I think, like Calfee, you can get open tube, but double-diamond and lateral tube as well.

zonatandem

Here is a suggestion to folks that flex a frame under hard pedaling conditions:
Ride your tandem hard with single bike following you to notice if there is flex.
Now put pedals 90 degrees OOP, under same conditions.
We've done that and there was definitely less flex riding OOP. We are a light team @ just under 250 lbs.
Pedal on TWOgether!
Rudy and Kay/zonatandem

Dean V

Is there any proof that a stiffer frame is faster?

Homeyba

I think it's pretty obvious that if the power you are putting into the pedals is contributing to side to side movement instead of forward movement that you are not going as fast as you could be so the answer is a stiffer frame won't make you faster, the answer is that a whippy frame will make you slower. The million dollar question is by how much. I would guess that it isn't a lot but when you are racing a little bit can be the difference between winning and loosing.

I'm 220-240 myself and have raced with a 180lb stoker (see pic below) which put us over 400lbs (geez!). I can say that my Calfee is more than stiff enough. In fact, when running HED3 wheels it is too stiff, to the point of being a little squirrly at speeds above 60mph on bumpy roads. With the Zipps and Topolino's it's not an issue so I know it's the wheels. I don't know of a stiffer wheel than those HED3's. When I ordered my Calfee my weight and riding perameters were all taken in to account. I know they can/do taylor their builds to the specific riders. While I haven't weighed my frame I know that it is a little heavier than my friends, who weighs 60lbs less than I do.

merlinextraligh

I'm pretty confident based on the responses in this thread, and other discussions that Calfee can build what we want, perhaps with a little more stiffness than a garden variety dragonfly.

But I really like the idea of a Paketa VR2. Before we make I decision, I'll talk to Dave Walker, and also try to test ride one.

monsieur_cyfac

Hello everyone! Eric from Cyfac here. It's my first time posting and I'm glad to "meet" you all!

I thought i'd reach out to see if I can provide any information or assistance about our frames and how they'd potentially suit you.
As Ritterview mentions, we do have a variety of configurations available. Because we build in steel, alloy, and carbon, the budget and project criteria that we can meet are quite varied. Whether you want a fully-loaded touring rig, something for performance, or a great "does everything" set-up, we can dial in the project scope to meet your desires.

Relative to stiffness, we have both alloy and carbon that are going to deliver.

Alloy - certainly a very stiff material. Ours feature 7005 series, triple-butted, T5 heat-treated and variably shaped tubesets both from Columbus (Zonal) and our own (Nerv alloy). Alloy allows for a very stiff yet light frame and because of the shaping, butting and overall wheelbase of a tandem these frames are quite comfortable (some folks immediately dismiss alloy as being too harsh but this requires a second look). We have built road, touring, and track frames in this material for recreational, elite, and professional levels and have the experience necessary to adapt the project to fit the tandem pair.

This is a track version, featuring the extra transverse bar spanning front and rear triangles to really stiffen the front end (perhaps overkill on the road but very necessary on the track).



Here is another permutation with a more conventional alloy configuration.

Here is alloy front paired with a carbon rear triangle.


With CARBON, we are using arguable the most advanced tubesets for tandems. The tubes are incredibly shaped, featuring various profiles adapted to the specifics of the rider pair. We get optimal stiffness and rideability through the use of different tubes, different configurations and the carbon stratification process that we employ at each tube junction. This changes the feel of the bike and perfectly dials it in to meet the requirements of the project. Additionally, we are the only builder to use Kevlar at each tube intersection to further enhance durability and stiffness. Last year, our best tandem pair won the paralympic world championships on our DUO CARBONE. The pair is about 330lbs and VERY fit. So, more important than weight, their output, handling abilities, fitness level, and competition demands were central to the project's success. We are building for Olympic pairs throughout Europe and Asia now!



Here's a private-label version we do for a partner in the UK.



And, here's another with just a paint variation to show a different look. On the paint, we really have the skillset to get the exact look a tandem pair desires.




I'm happy to help with any more information. I'm the co-owner of Cyfac but based in the US so it's very easy to work with us!
Please reach me at esakalowsky@cyfac-expert.fr with any questions.

merlinextraligh

^ Very cool. I'm betting the two guys with the Rainbow stripes put out a little power.

Krenovian

Beautiful bikes Eric! I've admired Cyfacs for years. Thanks for posting and welcome!

twocicle

During our initial shopping last year for a used Calfee frame, we came across a 2009 DragonFly* in our size Med/Small. It had the basic "stiffen" option which entails a larger (and perhaps thicker?) top tube for the complete length. Discussion with Calfee, Mel (Tandems East) and others, indicated the stiffen option was not needed for us (~165lb captain / 95lb stoker), alters the ride feel somewhat and that it does add some weight (.5lb or so). I believe they have additional frame stiffening tricks up their sleeve as well, but that is the only one I came across during our hunt.

Calfee has built so many tandems over the years for all types of teams including racers, that I would have confidence of them matching up any team type with the correct configuration.

For our new 2013 Tetra frame currently being built, the only election I made strictly for stiffness performance was to opt for a 1.5"/1.125" tapered headtube and matching ENVE 2 fork. However, Calfee noted that even a straight steerer version of the ENVE 2 is a noticable performance improvement over the AlphaQ fork provided with previous releases.

Another option we choose - S&S couplers, has the known side-effect (benefit?) of stiffening the bottom and top tubes a touch, as the fairly solid couplers replace equal sections of lightweight tubing. Yes, the couplers add some poundage, but that is a necessary compromise to get the travel tandem we desired. My target body weight this year will be -2lbs to compensate

I thought the 2007 Tetra frame was nicely balanced already, so it will be interesting to see how the new frame w/couplers and beefy fork/headtube feels by comparison. It should be nearing completion & shipping very soon. Last I heard, the target date (end of Jan) was still on schedule.

* AFAIK the TX shop owner still has the nude-finish Dragonfly for sale as either frame only or built-up to whatever components you want. PM me for contact info. FWIW, Calfee told me they would certify this frame from that dealer, plus do a full paint job for $600.

Team Fab

I have been drooling over a Cyfac track tandem for a few years now.

How much would a basic aluminum frame cost?

teamdonterri

I suggest you talk with Mike Moore at Calfee for info on stiffness and sizing as most all their frames are "custom" built. You will not have a flex problem with the large Enve tubing Calfee uses and with the way all the joints are wraped. Although a Paketa frame may be a little lighter for racing we chose the Calfee for the strength and ride qualities of carbon, and not needing paint (we got ours in the nude finish) we never have to wory about chipping or scratches in the paint that would expose the magnesieum of the Paketa.

Not bashing Paketa, we almost bought one. But for century rides and fast group rides the Calfee fits all our needs with no worries when caught out in the rain.

DubT

We also bought a Calfee and are extremely pleased with the ride. I personally would not even consider a magnesium frame, to many variables, the possibility of corrosion and as far as I know only one builder in the this country using the material. How many professional riders do you know who are riding on magnesium.

i may be wrong but it is my belief that if a frame is too stiff it will tend to bounce and the wheels will have a tendency to come off of the ground which would slow you down.

I am totally amazed at how our bike is stiff yet compliant, does that make sense? The ride is extremely smooth yet when we hammer it does not seem to flex at all. We are senior citizens and our team weight is right at 290 but we can still roll along at a decent pace when we want to. We own most of the Strava segments in our area.

Wayne

monsieur_cyfac

I don't want to be too sales-y on this site. Drop me an email at esakalowsky@cyfac-expert.fr and I'll be happy to give you more info.

Thanks!