Kirk Tandem

[bhungerford]

Just saw this in Oakley Cycles, its half built up, and absolutely beautiful. Well done Dave! :beer:
sweet... (http://www.kirkframeworks.com/blog/?p=83)

[Sandy]

After you click onto the link and see the photo, click onto the photo and you will see a much larger image and you can really appreciate the work done in creating that beauty.


Sandy

[Sandy]

A question for you, if I may. How can you figure out the stresses that might exist at certain points within the frameset? Is there ever any concern that some portion of the frame may be overbuilt and more importantly some underbuilt resulting in an actual weakness in the overall structure as forces are transmitted throughout the frameset? How do you know a frameset is structurally sound? Experience? Confidence in the strength and integrity of the tubing? Confidence in yourself in the design process?

In essence, I am asking how do you know, with all of those tubes positioned at varying angles and joined together at certain points, that forces transmitted through the entirety of the frameset will not ultimately cause a failure someplace because of the design and positioning of the tubes?

This question is not being asked specifically about a Kirk frameset but all framesets, especially ones like tandems with so many different tubes and joints.

I hope my question makes sense and is meaningful.


With bad joints,


Sandy

[zap]

Pretty cool.

[Cinci Jim]

I stopped by to drop off the Captain's saddle and discuss where to put the cable disconnects. It does look amazing! Oakley will finish it up early next week - I'll take some pictures of the finished build and post them at that time. David at Oakley has had it in the window - I think it is the easiest place for him to store it. He said many people have stopped by to look at it or come in to ask about it. Maybe Dave will get another tandem order out of it. I'm thinking I need to take a 1/2 day next friday!

Going to do some little rides with it to start with - I don't have a hotel in Portsmouth so TOSRV is not going to happen.

I'm thinking it's first big ride will be STP as a one day ride.

By the way Dave - everyone who has seen it marvels at the fillets on the headtube.

[rwsaunders]

That's some serious plumbing. Nice bike...it'll be neat to see it built.

[bhungerford]

totally agree on the headtube fillets Cinci Jim. the whole package is very well done.

[dookie]

i don't know that DK uses it, but computer modeling using finite element analysis is a common method.

FEA (http://en.wikipedia.org/wiki/Finite_element_method)

Ah yes ... Finite Element Analysis .... More fun then a barrel full of
Stochastic Differential equations. :D

[goonster]

How can you figure out the stresses that might exist at certain points within the frameset?

Over 100 years of trial and error, with builders constantly pushing the envelope trying to build lighter bikes, plays a big role here, methinks.

[Sandy]

i don't know that DK uses it, but computer modeling using finite element analysis is a common method.

FEA (http://en.wikipedia.org/wiki/Finite_element_method)

Thanks. I considered that possibility. I assumed that larger manufacturers like Trek/Cannondale/Giant would incorporate that in an ongoing basis and would have employees who were well trained in the field. That is where I would think a larger company would have a distinct advantage. Greater expertise and qualified employees to spend the necessary time. Dave Kirk, does it all, with the exception of painting, if I am correct, and he only has limited time.


Computer model perfection,

Serotta Sandy

[Sandy]

Over 100 years of trial and error, with builders constantly pushing the envelope trying to build lighter bikes, plays a big role here, methinks.

Methinks you are correct. Dave Kirk undoubtedly received great experience at Serotta in not only building bikes, but in the development portion of the business. 100 years of trial and error and then great experience by Dave would be remarkably helpful.


Sandy

[slowgoing]

yeah, but what does it weigh?

:)

[Smiley]

Methinks you are correct. Dave Kirk undoubtedly received great experience at Serotta in not only building bikes, but in the development portion of the business. 100 years of trial and error and then great experience by Dave would be remarkably helpful.


Sandy
It will be interesting to see if Dave hit his build time estimates in making this tandem. I think sometimes tandems are best left to the guys that make them on a regular basis. Don't get me wrong Dave's work shown here is excellent as well as what I saw at NHABS with a Kent Erickson tandem there. But if your not making enough of these to set up your jigs and know the subitle issues of using a modified road/MTB grouppo that works with tandems you maybe in a pickle. I'd sure would like to see the final build and would like the owner post how easily this sucker packs in an S&S case since the tandem was designed as a coupler and this should be a large consideration in the design. I chose a Compac tandem by Co-Mo strictly on the basis on packing into a case. I trusted Co-Mo's expertise that this Periscope Torpedo design rode well. They did not let me down on both aspects of the purcase. I am sure the owner of this bike will be thrilled with his outcome too.

[Ti Designs]

yeah, but what does it weigh?

Depends on who is on it. The weight issue on single bikes is amusing 'cause there are so many 15 pound bikes out there with owners who could use to lose 15 pounds. Tandems are twice as amusing 'cause how they climb is as much a function of timing as it is power/weight ratio.

[David Kirk]

It will be interesting to see if Dave hit his build time estimates in making this tandem. I think sometimes tandems are best left to the guys that make them on a regular basis. Don't get me wrong Dave's work shown here is excellent as well as what I saw at NHABS with a Kent Erickson tandem there. But if your not making enough of these to set up your jigs and know the subitle issues of using a modified road/MTB grouppo that works with tandems you maybe in a pickle.

Whether intended or not I feel called out here in a way so I want to respond. I do my level best to not comment on my work here in someone else's house but when called out I will respond.

I've built more than a few tandems over the years. Not as many as some but lots more than other builders. One thing I do a bit differently than some other builders is that I don't rely on tooling to do the work for me. I'm a fabricator first and foremost and I make bicycles for a living. So some builders are framebuilders first and others are fabricators that build frames. For better or worse I fall into the later camp. This means that being able to produce a one off takes little or no time more than making a series despite the fact that a special jig isn't in the shop. Any extra time is spent in the design process and in sourcing materials I don't normally use. By being able to design and make my own tooling and processes I'm just as able to make single and tandems as I am to make unicycles and race car roll bars. It's all hooking pipe together and that is what I've spent my entire adult life doing.

As for the time frame. The frame was delivered ahead of schedule as I recall and I personally estimated that it would take two weeks to complete the build and it took one day less than that. After you've built this many bikes the guess work is taken out of the equation and hitting my times is pretty simple. I very rarely ever deliver a bike late. Not that is doesn't happen but I'll bet that I deliver 95% of my bikes early. If I don't hit my time estimates then I'm not doing my job.

dave

[pdbrye]

Dave, that frame is just plain OFF THE CHARTS!! Absolutely Killer!

Paul

[Ahneida Ride]

Nice Bike Prof. Kirk ..... :beer:

[David Kirk]

Nice Bike Prof. Kirk ..... :beer:

Much thanks. It was fun to build and I hope it shows.

dave

[Cinci Jim]

It will be interesting to see if Dave hit his build time estimates in making this tandem. I think sometimes tandems are best left to the guys that make them on a regular basis. Don't get me wrong Dave's work shown here is excellent as well as what I saw at NHABS with a Kent Erickson tandem there. But if your not making enough of these to set up your jigs and know the subitle issues of using a modified road/MTB grouppo that works with tandems you maybe in a pickle. I'd sure would like to see the final build and would like the owner post how easily this sucker packs in an S&S case since the tandem was designed as a coupler and this should be a large consideration in the design. I chose a Compac tandem by Co-Mo strictly on the basis on packing into a case. I trusted Co-Mo's expertise that this Periscope Torpedo design rode well. They did not let me down on both aspects of the purcase. I am sure the owner of this bike will be thrilled with his outcome too.

I wanted to comment on this as well. When I got on Dave's list just after NAHBS in 2008, I had the mind to have him build me a single fillet-brazed frame with Terraplane seat stays.

After talking with Dave a few times and thinking about it over the summer I decided to ask if he would build me a tandem. Dave said he had built tandems for Serotta and he would feel comfortable doing it again. Dave did not have to say that - he was going to build me a frame regardless - tandem, single or unicycle!

As time passed and we talked further, I could tell Dave was getting excited about the project. Don't get me wrong, I think Dave enjoys every frame he builds and really takes a personal interest in getting to know his clients, but this was different and I believe he enjoyed that aspect of the project. More than once Dave & I would be done with the "work" part of the phone call in less than 5 minutes and then spend over an hour talking about other topics - politics, cars, frame building, etc.

Dave built the frame in less time than he expected and he sent pictures everyday of the progress. If anything I delayed him as I was not as quick in replying with the contact point info and in replying to his follow up questions as I should have been - Dave took it all in stride though.

Dave was a pleasure to work with, shared his knowledge quite freely and I'm quite sure he would not have allowed me to talk him into making a poorly designed frame - no matter what. I'm planning to pack it into 2 boxes and Dave used that in his design process. Dave make a mockup S&S box to make sure everything would fit.

Several people, with far more experience than me are quite impressed with the workmanship as well and have marveled at the frame.

I honestly think the only thing better looking than the frameset will be the built up bike itself.

But I'm biased :rolleyes:

[csm]

let's see some built-up pics already!

[Cinci Jim]

let's see some built-up pics already!

On Saturday it only had cables, bar tape, captain's saddle & stoker stem left to go... the shop was closed on Sunday & Monday so it should be done very soon!

The blue on the inside of the drive belt perfectly matches the blue of the decals - too cool!

[JohnHemlock]

I'm just as able to make single and tandems as I am to make unicycles and race car roll bars. dave

What is the lead time on a unicycle? I graduate from clown college next year and want to treat myself.

[Ahneida Ride]

Ever once in awhile, I pick up a Stereo Magazine .... and of course
they review speakers and they always compare em to "reference speakers".
But they never tell ya what dem reference speakers are ...
I'd love to purchase if I could ever afford em, doz "reference speakers".

Well in the bike world, I humbly submit that that "reference quality" is
Prof. Kirk's work. ;)

[Dekonick]

Nice work - as usual.

Beautiful.

[whitecda]

Sure, I'm out of town otherwise I'd be at Oakley checking it out. Just my luck.

Don

[zap]

Dave & Cinci, what are the specs on that tandem.

At some point we will need a take-apart tandem and would love to work with a custom builder to try some different idea's. CoMo was great in the past with simple one off touches.

[Cinci Jim]

let's see some built-up pics already!

Here you go...

http://forums.thepaceline.net/showthread.php?t=58587&page=2&pp=15

[csm]

Here you go...

http://forums.thepaceline.net/showthread.php?t=58587&page=2&pp=15

that looks great! I think orange is the new black.

[Pete Serotta]

I love the looks and the color...VERY VERY nice..... :)


Pete