oldacura

I notice that Paketa is now a sponsor of this forum.

I have seen only one of these in person. I don't know that the owners frequent this forum. They have had the bike only about 2 - 3 months. They came from a steel tandem (wrecked in an accident). They seemed to really like the Paketa.

Most forum members who go high-end go carbon fiber. For those who have, did they consider the magnesium Paketa? If not, why not? If so, why did they choose CF over mg?

Anyone on this forum try or own a Paketa?

VaultGuru

Talk to Rick at Gold Country Cyclery. He is a Paketa dealer and can give you the pros and cons. Paketa is a beautiful bike.
https://www.tandems-recumbents.com/tandem.html

Stray8

Don't know about them personally, but they do look nice and we've heard that Paketa sales are reportedly booming...

I also see that it is the "Fastest Tandem in the World".













.

Ritterview

Magnesium as a material has been around awhile, but has never taken off as a bike frame material, though it is undoubtedly light. The magnesium Pinarello Dogma was raced successfully (including winning the Tour de France in 2006), but never became popular. The 2010 Dogma has reverted to carbon.

Do a search for magnesium on the weight weenie forum, and there is no evidence of magnesium making any headway against other materials in lightweight bike components. A brake here, a stem there, but that's about it.

Paketa makes magnesium single frames, but these haven't electrified the weight weenie world.

The reason a magnesium tandem frame is interesting is because there isn't any Taiwan factory-made carbon tandem frames. If there was, we'd all want that, and not be interested in magnesium so much.

oldacura

On a recent ride, a couple had just acquired a Paketa tandem. Coming from a steel Ericson, they liked the light weight of the Paketa. They didn't have a lot of miles on it and I didn't get a chance to talk at length about it.

The Paketa "factory" (big shed) is just about 2 miles from my house. I was given a tour by one of the principals. He is a metallurgist at NIST (National Institute of Standards and Technology) in Boulder. He claims that aside from the light weight of magnesium, the metal has an inherent damping factor that makes for a smooth ride.

Because their volumes are so low, I assume all tandems are built to order.

They buy extruded magnesium profiles (of their own design), cut them with a tubing cutter, cope the ends to fit together and weld them up - just like any other custom made aluminum or steel frame.

I did not take the opportunity to test ride either a single or a tandem.

Ritterview

FWIW, there is a review at Road Bike Review:


Hey, that bike sounds like the description of the Paketa shown at the RMBS, which is owned by one of the principals at Paketa. This may be a review is of their own bike. I think a little bias might have slipped in here.

WebsterBikeMan

Although they did say "yellow", which I take to mean the colour of the frame...

rmac

"Paketa Bikes V2 Racing Tandem

Summary:
Our V2 is our second tandem. We'd been riding an Aluminum framed C'Dale Ultegra equipped bike for about 7 years, and looked to upgrade to something faster when our C'Dale started to get tired. We looked at many top of the line tandems, including carbon frames. Being a Materials Engineer by education and profession, everything I read on the Paketa web site about their Magnesium framed bikes sounded appealing, and made sense. With Mg tubes, you get all the benefits of carbon, even more so (light weight, stiffness and vibration damping) with the addition of ruggedness. The Mg tubes are thick, stiff and almost dent proof, so no fear of breaking this frame."

Well, unfortunately friends of ours broke a seat tube. They sent it back and it was repaired but I don't think you can say "no fear".

Carbonfiberboy 

There might be a question of fatigue life. Aluminum and magnesium share the property of not having a "fatigue limit." That means there is no loading below which these materials do not fatigue. Steel and titatium have fatigue limits, meaning it's possible to engineer frames in these materials which will last indefinitely. Calfee says, "Carbon fiber also has a better fatigue life than steel, titanium, or aluminum, and the resins typically used to bond the fibers offer extremely good vibration damping."

Ritterview

Correct. And that they are shipping the bike to TX, not staying in Colorado. So, maybe it is a real customer. If so, this customer should be contacted, so he can tell us all about it here on the tandem forum.

It could be that the RBMS show bike is equipped just as they sell to customers. However, ZG brakes, with their literal, not figurative, neck-snapping performance, hardly seem like typical tandem spec.

JqNav

My wife and I own the yellow Paketa tandem under discussion. It was a custom build by Sixties Cycles in Lafayette, CO. I'll be happy to answer any specific questions on the bike.

JqNav

Here's a picture of us taking the bike for a test ride in CO before we had it shipped home to TX . . . . .

Ritterview

Welcome to the BF Tandem Cycling subforum, JgNav!

A couple of questions:

So, your magnesium frame has neither corroded to powder, nor burst into flames?

The ZG's provide sufficient stopping power?

And, might I suggest two threads?

Pictures of happy tandem couples?

What's your tandem weigh? [yours may be setting a record here]

mrfish

Just to scotch a rumour, it's actually very difficult to get bulk magnesium (like a bike frame) to burn, since it's a very good conductor of heat so just conducts localised heat away. Experiments on a Kirk Precision (injection moulded magnesium frame) showed that a lighter or match won't do it.

Regarding the Paketa, what spacing are the dropouts?

I'm also interested to see people using new CR420 wheels on the tandem. How much do they weigh? Is it a tandem specific hub? On my single bike I found they were OK, but with a really poor rear hub (too narrow flanges, difficult to adjust, bearings either loose or on the way to self-destruction as just too small). On my own single wheels I've replaced the rear hub with a far far superior Goldtec (UK made) and they work nicely now.

Just a quick tip - the only way I found to get the rear hub adjusted correctly was to buy two (19mm IIRC)cone spanners then adjust the hub while mounted on the bike to avoid the axle rotating then tighten and lock down until there's 0.5mm play at the rim. In my case this needed to be done monthly, and if you over tightened it at all then you were looking at installing new bearings as they're too small to take any pre-load. Basically the hub is crying out for a split-nut with allen key like Campag hubs use rather instead of its silly double locknut design.

merlinextraligh

How does it compare to the Cdale with regard to frame flex/stoker wag?

WebsterBikeMan

If we're derailing the thread... aluminum and even steel also burn quite well, if in either fine powder (dispersed in air) or thin enough wire form. The key is getting the oxygen to the fuel fast enough.

JqNav

Nope, has neither corroded to powder, nor caught on fire . . . . however, we're hopeful with more training, a decent downhill and a tail wind; the latter will be achievable . . .

The ZG's are significantly better than our Cannondale's XTR setup, but not quite as good as the Cannondale after I retrofitted it with front and rear Avid mechanical discs. By the way, the Avid retrofit was motivated by a "his and hers" hospital visit due to not being able to stop in a timely manner . . .

rmac

I would think that magnesium would corrode fairly quickly if left unpainted or if the paint were scratched. Is this the case?

Phantoj

The fatigue limit is a myth.

Stray8

Unpainted magnesium oxidizes so quickly in air that the magnesium oxide coating itself protects the rest of the metal. There are no worries about it turning into dust. Many high end compound bow risers are also machined from magnesium.


.

JqNav

Bulk Mg does not ignite that easily, but if it does, it's pretty spectacular. I'm a materials and metallurgical engineer, and my first job was in a foundry that cast magnesium components for the aviation industry. Molten magnesium exposed to air is pretty spectacular to say the least . . . Mg get's a bad reputation primarily from the aviation and motorsport arenas. Mg alloys have been the materials of choice for race car wheels forever and up to about 10 years ago when other alloys have been developed. They have excellent strength to weight ratio, good toughness, and display some "memory". This "memory" is quite interesting, but wheels would often come off race cars slightly "out of round" due to impact (especially rally cars), and left for day would return to their as cast shape. There's plenty of impressive footage around of Mg wheels burning, but the car is on fire first, and the Mg wheels catch on fire later. Even driving just on the rim with sparks spewing off the rim, they won’t catch on fire. Any case, getting side tracked, yes it will be very difficult to get an Mg frame to burn, but if you ever did, stand back as it will disappear in a spectacular white flash . . . . . .

Spacing on the dropouts is 130mm. This was the toughest call for us to make, as at a combined 330lb rider weight, we're pushing the envelope on wheel durability. It was a tossup between a greater selection of higher performance wheels to choose from at 130 mm, vs heavier, slower less available tandem specific rims to gain better durability. As it stands, I'm not completely comfortable running the AC420's. We have had no problems yet, but also haven’t posted that many miles. David Walker of Sixties Cycles is building us some Zipp 808's onto White Industries hubs. These will be bomb proof, and I'll be passing the 420's onto my single bike . . . . and keeping them as "back up" wheels for the tandem.

The 420's are not tandem specific, and I believe AC has done a redesign on the hubs???? Remember this coming up in conversation with the builder, but can’t recall the details. I think the weight is about 1650g for the set . . . . It's on AC's web site.

Thanks for the tip on maintaining the rear hub. I need to check it out to see if the supposed "new design" is different to that which you describe.

JqNav

Zero frame flex on the Paketa . . . it's unbelievably stiff. That's the weird thing about Mg, it's super stiff, but yet displays excellent vibration damping at the same time. The first couple rides are a little surreal because it feels like the bike is "gliding" over the road. You get zero buzz from the frame, and we don't exactly have the smoothest roads in Houston.

The C'dale was actually also pretty stiff, at least as compared with my Litespeed Ti single. Watching the BB on the Litespeed can be hypnotizing. It did have a little "BB wag", but completely livable. The C'dale was way more "buzzy" on the road though.

WheresWaldo

We had the same dilemma, deciding what rear spacing. Our decision was to compromise and build 132.5mm spacing, then we could use either a road or mountain hub depending on availability. Still hoping to build a set of carbon wheels with either a DT or WI MTB hub. If we do we will certainly use more spokes than what is in the AC420's.

BTW, beautiful tandem!

Ritterview

By ZG's, you must mean Ciamillo's more robust Negative G's, and not the lighter but wimpier Zero Gravity calipers.

The Negative G's are one of the stronger light brakes, according to the Velo News Review. I entered their data into a spreadsheet. Then I made a scattergram with Excel (and that not very well).

Anyway, the scattergram shows that there are two relatively strong (deceleration >8 m/s/s) light brakes. The eebrake and the Negative G.

tandemnh

My wife and I purchased a 2007 C'dale a year ago (Sept '08). We love the ride it is stiff, fast and straight and I find it very responsive. Back in July I saw and got to lift a Paketa tandem, I was amazed. With 3 kids in college right now the price is a bit challenging for now... but in the future....

Realizing you don't have a great deal of miles on it:

1. Which do you like better?
2. What are the significant differences?
3. What does the wife think, worth the money?
4. What was you motivator to step up to the Paketa, does it offer something the C'dale does not?
5. Are your rides on the Paketa similar to the C'dale rides or do you find yourselves riding maybe further?

Thaks, look forward to your response.