obrentharris 

I don't think any of the interested parties need me to tell them how to run their lives, businesses, communications.
But if anyone here wants to talk about tandems...
Brent

reburns

Dean V

This is exactly why it shouldn't of been posted. It effects peoples livelihoods by an unknown person with unknown experience being critical in a public forum.
It is a one sided view point from the OP but also the problem is even if there is nothing wrong with the bike it would very hard for the builder/supplier to put forward an effective argument here.
Which is no doubt why they are not bothering to try.

124Spider

​​​​​​
Nonsense!

It's one-sided only because the seller went dark. If something's wrong with the bike, seller can explain what it is, and what they're doing about it. If nothing's wrong with the bike, seller can explain why it wasn't shifting right and why an experienced tandem team found it unridable.

Stifling the free flow of information doesn't help the consumer.

Dean V

How do you know how experienced they are as a tandem team?
I have one "noodley" tandem. An old Bob Jackson made from Reynolds 531. It is very flexible by any modern standard and it is no slower than our Cannondale.
We have a custom steel TT tandem which is just crazy flexible but also very fast.
21min for a 10 mile TT. Yes, you need to be smooth and no sprinting, but it is made for a purpose.
From initial reports it seemed the OP was very happy with how the Landshark rode and then suddenly it was terrible?

act0fgod

After reading this thread I'm more likely to buy a new bike through a tandem specific retailer as opposed to direct from the manufacturer. It seems TE has proven helpful.

merlinextraligh

Well having taken constitutional law, the 1st amendment involves governmental limits to speech.

By its express terms: "Congress shall make no law..."

The 14th amendment extends the protections contained in the Bill of Rights to the states. So the 1st amendment also limits state and local governments from curtailing speech.

But without governmental action, which is not present here, there is no 1st amendment issue.

mtseymour

Pic 1


Pic 2


Pic 6


Pic 3


Pic 7


Pic 4


Pic 8


Pic 5
I decided to talk to the parties involved because I’m surprised by the outcome, and also because our teams are similar in size (weight and body proportions). I had a short chat with John Slatwa and PM with Woodcycl to get some background info, and couldn’t connect with Mel. My conclusion is that good intentions were undermined by subtle design choices leading to un-intended consequences. Taken individually, these design choices would have minor consequences. When combined, however, the impact on ride quality was much more than expected.

1 Sloping top tube
To provide enough standover for the captain, the Landshark has a fairly sloped top tube (ie. compact geometry). The top tube is straight from the head tube all the way to the stoker’s seat tube. Since Woodcycl has a short inseam, the top tube has more slope than typical compact frames. The result is that the rear triangle is fairly small and requires a long seat post (see pic 1 & 2). Previously, Woodcycl rode a 2005 Cannondale. This design is less elegant but stronger because the rear compartment is properly sized (pic 3). The lateral tube doesn’t hurt either.

2. Seatstays are not supported by top tube
From a structural point of view, it’s better for the seatstays to join the stoker’s seat tube at the same point as the top tube. However, the sloping top tube means that the seat stays would be too flat (like the Co-Motion Periscope), and too flexy for an adult stoker. It would also require a really long seatpost (like the Periscope).

The decision was made to position the wishbone seatstay about 2” higher than the top tube (pic 4). This joint is weaker because the top tube is not directly positioned to oppose the team’s weight.

3. Smaller Rear Triangle
Even with the unusual seatstay joint, the Landshark still has a smaller triangle than the Cannondale. A smaller triangle combined with flatter seat stays with be more flexy than a taller triangle. The decision to use bowed and curved seatstays (reminiscent of the Cannondale Synapse SAVE design) also added more flex (pic 5). By way of comparison, our Calfee has a slightly bigger rear triangle with a solid junction of the top tube, seat tube and straight seat stays (pic 6). I prefer the Landshark’s looks, but our Calfee’s geometry is efficient and comfortable.

4. Weight distribution
Unless other teams riding a small frame, Woodcycl has more weight over the rear triangle because his stoker is almost the same size. A thicker carbon layup in the right places would have improved the stiff in the rear section.

5. Long Rigid Seatpost
A long rigid seatpost will exert more force on the rear triangle, especially when the seatpost claim is well supported by the top tube. A suspension seatpost like the Kinekt seatpost (aka Bodyfloat) will smooth out the stokers pedal stroke and reduce excess flex.

Although Woodcycl has returned the frame, there are three relatively simple modifications that will improve the ride. The first option is to add a gusset to the seat tube and seat stay junction. One example is the Santa Cruz frame (pic 7).

The 2nd option is to brace the rear drop outs. Calfee uses a brace on the left side to handle the stress from the hydraulic disc brake and 180mm rotor (pic 8). Adding this type of brace on both sides will increase stiffness.

The 3rd option is to add more carbon layers to the right chain stay. This would be similar to the Pinarello Dogma with the asymmetric chain stays to counter pedaling forces. This concept is useful for tandems because the pedaling forces are similar to elite single riders.

oldacura

Interesting analysis. Based on the OPs description of flex & shifting, I assumed that there must be something wrong (i.e. broken) with the frame. When I see the photos, that is a long, short frame. All else being equal, the torsional rigidity of the frame is proportional to the cube of the height. With no lateral tube, there is a lot of twist on that frame with little height to resist it. Kind of like making a convertible car by cutting the roof off of a regular car without making any provisions to provide stiffness beneath the floor.
If LandShark took the frame back, will they be able to fix the flex with some of the modifications proposed by mtseymour or is it just a lesson learned?

merlinextraligh

Very interesting analysis MtSeymore.

Points out the risk of one off custom builds.

From all this, I'd give a Landshark a plus for taking care of the customer in the end, but of a bit a question mark for building a bike that did't meet the customer's needs.

Hard to really assess "fault" without knowing what was discussed, but I would hope a custom builder would 1) get a good understanding of what ride qualities the customer wanted, and warn the customer off from design choices that might compromise what the customer was actually looking for.

mtseymour

Carbon is an easy material to modify or repair. A carbon frame is basically sheets of carbon fabric ("prepreg") bonded by resin with heat and pressure. It's much easier than repairing a steel or ti frame (aluminum is practically un-repairable).

Calfee has repaired/modified over 12,000 frames and offers a 10-year warranty: https://calfeedesign.com/carbon-repair/

I'm confident that Landshark can easily do the modifications. My brief conversation with John suggests that he had limited contact with Woodcycl (before and after delivery). It's possible the Mel was more involved, but something seems lost in the translation about the relationship between frame geometries and ride characteristics.

mtseymour

To be fair to Landshark, custom builds are challenging. I'm on my 3rd tandem and countless single bikes (aluminum, steel, ti, and carbon). Practically every build required tweaking (eg. custom stoker stem) after taking delivery. I also know a few factory-sponsored riders who test new bikes. It's unusual for a high-end bike to go from the drawing board (or CAD program) to production model without changes to the prototypes.

The good news is that carbon is the ideal material for custom builds and tweaks. I'm confident that this Landshark can be easily modified to provide a dream ride for the new owners.

bwebel

That is sadly an understatement. Even when one is completely clear to the builder, and the drawing reflects what you want, it can still come out wrong. I just took delivery of a very nice custom steel frame, that I was very specific about where I wanted the bottle cage (and it wasn't unusual positioning), and when I unpacked it and when to put the front derailleur, I realized he put the cage bolts too low. So I either use a pipe clamp on a very nice bike, or it annoys me every single time I reach for the water bottle, or I am a jerk and insist on a new frame be built because he didn't do it like I asked and is clearly indicated on the build sheet. Still not quite sure what the outcome will be, but it does leave a sour taste in the mouth when one shells out that much money.

Artmo 

Hear! Hear! Why should the problem have been discussed publicly before the manufacturer or supplier had been given the opportunity to rectify it? Had the OP dealt with this privately THEN reported the outcome, TE and Landshark would be viewed in a totally different light. 1st Amendment? What about commonsense?

merlinextraligh

Because it was discussed publicly, I think many of us learned something..

To me more information is usually better than less.

PMK

Yes and no to the easy to repair. On a molded frame there is no means to internally accomplish the mods unless you cut it open. On a Calfee with essentially a tube and fillet type construction, absolutely.

The key to being easy and making it right for the owners is you need to know where the flex is and how to add plies, at what ply orientation, while not building a stress concentration somewhere else.

Situations like this are difficult to be correct on all accounts. I have no dog in this fight, but certainly do not like disappointments nor like to read about others having issues. With all that said, there have been more than a few requests for me to quote and accomplish work on both bicycles and aircraft that I simply said not interested. Not interested because up front I could see that even perfection would not be acceptable. In a case though where more needs to be done to make a reasonable customer happy, discuss, devise a plan and go forward. Seems they did that.

As for the flexy tandem, my suspicion is the bike will be ridden by another team while the builder follows to see what is going on with it. At that point it is either going to be for a lighter team, or will see additional work to stiffen the frame a bit. I doubt it will be cut up and scrapped.

oldacura

I also think this is an example of the evolution of bike frames in general (both single & tandem). The traditional old school diamond frame had evolved based on round steel tubing for a reason. The strength-to-weight ratio was optimized based on the materials available at the time. Most older (steel) tandem frames had a lateral tube that added strength but added weight as well. As new materials and construction methods came available, radical frame designs began to appear (both single and tandem). Some of these designs pushed the limits of the geometry too far (this might be one of them). A frame designer probably doesn't know exactly where the edge of the cliff is unless he occasionally steps over it.

As others have stated above, this bike might be fine for a smaller, weaker team. If bikes are designed to handle the heaviest, strongest riders, they will be heavier than necessary for the average rider(s).

Leisesturm

I think it is more accurate to say that many of us think they learned something: avoid Landshark Tandems at your peril. And that may be an incorrect conclusion. I don't think the other poster was saying the situation should not have been discussed. The issue was when the reveal should be made. I don't know about you but it does not usually occur to me to report to a forum about something significant that is happening to me until quite awhile later. A number of recent purchases online have even come with highly visible request cards in the package asking me to avoid contacting Amazon or giving a negative review until after giving them a chance to resolve the situation. Clearly retailers are learning the hard way what uncontrolled negative feedback does to their business.

merlinextraligh

No, what I learned is some design consdierations in building a custom tandem

mtseymour

The construction method shouldn't affect the repair outcome. The majority of carbon fiber frames use a monocoque (or molded) front triangle, with the seatstays and chainstays fabricated separately (or bought off-the-shelf) and later bonded to the front section (eg. Specialized Roubaix, Cannondale Supersix, Trek Domane, Pinarello Dogma). The tube and lugged frames are less common, but are ideal for custom sizing (eg. Calfee, Parlee, Colnago). Both types of frames perform really well.

Leading repair shops like Calfee and Ruckus Composites have done many repairs with both types. If you go to their galleries, you'll see many examples of repair jobs for various top brands:

https://calfeedesign.com/carbon-repair-faq/#beforeafter
News & Tech | Ruckus Composites

It's even easier to reinforce the Landshark frame so that it has less lateral flex. I'm just surprised that Mel didn't offer to modify the frame. Although the Landshark may end up with another team, it's a waste of a beautiful paint job.

PMK

No doubt this being the internet, I have no reference of your experience or ability working with carbon composites, in the same way you have no gauge of my experience working with those materials.

While what you have posted is valid information regarding the means that small changes done to various stressed areas may be contributing factors in regards to the frames flex. Additionally, many of us that have ridden a Cannondale realize that those frames tend to flex less then most others regardless of materials used to construct them.

Your comments regarding construction methods and types is accurate. I still retain a differing opinion that in order to reduce the frames flex to an acceptable level is as easy as you present it. It may seem that simply adding more plies will solve most concerns, the logistics of possible increased stress, loads or flex at a secondary point becomes a concern. Add in that when plies are added externally, which in this case would be the method, the frames surface may require additional steps to obtain a a sleek smooth exterior surface, capable of flaunting a gorgeous paint scheme.

Within the composites industry, often, in jest, but also in truth, we state that paint hides a multitude of sins.

No doubt Landshark will follow the path that works best for them, and life will go forward. The Landshark tandems I have seen first hand are very nice, and if we were looking to buy a new bike, would still keep them on the short list of builders to look into.

mtseymour

That's a fair comment because "easy" is a relative term.

If we were talking about a $3-5,000 tandem, it may be impractical to strip the paint and assess the work to be done. This $15,000 tandem is either going to be resold to another team at a significant discount, or returned to the factory where it may be stripped, modified and repainted.

The alternative was to ask Landshark or another shop to evaluate the frame and provide an estimate of the fix. This option might have been more cost-effective and avoided the unfavorable speculation.

It may interest carbon fiber owners to know that Calfee, Ruckus and other repair firms will provide free estimates based on photos or in-shop examination (visual or ultrasound). Having seen a local firm fabricate and repair carbon fiber components for sailing (masts, rudders, etc), adaptive sports (racing wheelchairs), and national team cyclists (track frames, aero bars, etc), I'm fairly confident that this Landshark fix is on the "easy" end of the spectrum..

diabloridr

I've been watching this discussion from the peanut gallery, but can offer my take from building a custom tandem and a pair of custom singles:

Our retired Co-Motion Speedster required custom geometry to accomodate my beloved stoker. Co-Motion does not do direct to consumer sales, and we worked through our local shop who is (1) a Co-Motion Dealer, (2) the owner rides and understands tandems, & (3) we had a long business and personal relationship with. This transaction went off smoothly and we enjoyed the Speedster for 18 years before obsolence forced its retirement.

The same dealer worked with a builder (who shall remain unnamed) when we purchased a custom single for my stoker. She's small, and the bike reflects it: nominally a 43cm frame with 650C wheels. She loves this bike.

Subsequently, we had a second bike for her made working directly with a second builder (who shall also remain nameless). This builder usually works only directly with the buyer and was local to us (at the time). During the specification process, we made her existing bike available for any measurements they wished to take.. Our message to the builder was "This bike works for her, we're not looking to change the geometry in any way". The bike produced has some significant changes from her previous bike (for example, significantly longer chainstays). Asked to chose between the two bikes, stoker prefers Bike #1 without question (Bike #2 is now relegated to being a trainer bike). Looking back, I should have been more engaged in the build process than I was (For example, requesting a geometry drawing for approval would have been a good step).

Having an experienced LBS with whom one has an established relationship can be a huge advantage when dealing with custom bulders.

Juke41

Within the composites industry, often, in jest, but also in truth, we state that paint hides a multitude of sins.


This should not be the case ! the only layer of paint capable of "Hiding" is the primer and that is only if you use high build primer / filler or spray filler.

The typical build up of layers for a paint system are :-Etch Primer 10-15 microns, Primer filler 30-40 microns, basecoat (depending on colour) 10-18 microns and Clearcoat 30-45 microns.

At these thicknesses, paint will hide virtually nothing, if anything it will only highlight defects.

Even at the top end specification at 118 microns, on a tandem you will add around a kilo of weight.

It is a miss conception that the thicker the paint the better, the actual opposite is true, the thinner the paint system is (as long as specification is met), the better it will perform in both mechanically and durability testing.

The above is applicable to steel, aluminium and the majority of composite materials. Good quality Carbon Fibre also falls into this category. However, some carbon can be very porous and requires excessive use of primer / filler, this followed by the subsequent layers will add significant weight to the finished product.

A manufacturer of lightweight sports cars I dealt with in the past, boasted, this is the lightest body we have ever made, the carbon fibre was soooo bad, it took 16kg of spray filler to "hide" the defects - not so light now

If teams are conscientious of weight on carbon, go with a nude finish, this will also show the quality of craftmanship in the finished frame.

Leisesturm

You are still assuming that the frame needs less lateral flex. Classic first post bias. Not your fault, I see it time and time again. The first person to get their truth out there is the one that gets all the credibility and support and the other side simply can't win. Another team might not think the bike too flexy. Mel knows that. From his calculation it might make better sense to save that beautiful paint job for a team that appreciates it (and its weight). It can't be sold as 'custom' again, but it won't be a total loss either.