Kirk Frameworks

[David Kirk]

Originally Posted by fiamme red

Dave, I recall you writing that you built mountain bikes at Serotta. I'm curious why I've never seen an MTB with your name on it?

Thanks for the question.

Yes I did build lots of mountain bikes at Serotta and of course I raced offroad for many years.

There are no Kirk mountain bikes I suppose because I have more than enough road bike work to keep me very busy and I've never pursued building them. I keep meaning to build one for myself and my good friend Steve Garro of Coconino even sent me some tubes and parts to get me off my ass and build one but I've never been able to carve out the time to do it. I used to think it would be a good winter project but I'm so busy in the winter that I don't have time then. Maybe a fall project?

dave

[Joachim]

Hi Dave... what % of your road frame output per year is the JKS model?

[David Kirk]

Originally Posted by Joachim

Hi Dave... what % of your road frame output per year is the JKS model?

It's grown in a big way over the past few years. I now offer the JKS original (OS tubes - sloped top tube), the JKS Classic (OS tubes - level top tube), the JK Cross (OS tubes - cross geometry and clearances) and the JKS X (XL sized tubes) so there are plenty of bikes that fall under the JKS umbrella. I'd say that about 75% of what goes out the door is a version of the JKS.

Thanks for asking,

dave

[FlashUNC]

Not to put you on the spot, but any plans to begin building road frames with disc brakes?

If a buyer were getting a custom frame, would you recommend they build for disc brakes over traditional calipers?

[mnoble485]

So many money shots! I had the pleasure of riding with a friend who owned a Kirk. He was allways riding the best bike in the group. Also had the chance of talking with Dave at two NAHBS and he was nice enough to spend time with a tire kicker.

A big ups for sharing your knowledge here.

Mike

[David Kirk]

Originally Posted by FlashUNC

Not to put you on the spot, but any plans to begin building road frames with disc brakes?

If a buyer were getting a custom frame, would you recommend they build for disc brakes over traditional calipers?

I think we will see lots of road bikes with disc brakes soon. I have a road bike with them and the set up works very well but it a bit overweight with the current stuff available. Word is that that will be changing soon and I look forward to it.

I think that the brake choice, be it rim or disc brakes, will largely depend on how and where the bike is to be used. Do you live in flat place like Miami and the only time you get wet is when you get caught in an afternoon rain storm? The discs will offer little advantage. Do you live in Sun Valley and ride regardless of the weather? Then discs could be a very good choice. It really does depend on what work will best for that rider and I do not think one size fits all.

I hear a lot of naysayers talking about disc brakes and saying stuff like 'nobody needs those things' and what I think they so often mean is that they themselves don't need them. Fine then. What I wish we could get past in this biz is the tendency of some folks to think what works best for them is what everyone else should use. It's just not that simple - oh what an easy life it would be if everything was so simple. I think discs are a very good option for some riders - not all - and the folks that need them will have their cycling lives improved by their use. And the best thing is that if the guy in Sun Valley loves his disc bike that doesn't make the guy in Miami's rim bike all of a sudden suck. Both bikes suit their purpose and are equally valid.

I have a number of disc brake bikes in my queue and some will be coming up soon.

Thanks again,

Dave

[firerescuefin]

Why the Lotus for autocrossing?

What mods have you made?/ what percentage of the tinkering is done by you.

[David Kirk]

Originally Posted by firerescuefin

Why the Lotus for autocrossing?

What mods have you made?/ what percentage of the tinkering is done by you.

Before I raced the Elise I ran a Birkin S3 which is a modern Lotus Seven clone and it was the ultimate solo car - 1250 pounds with more than enough power and handling that supercars can only dream of. I loved it and won a few state championships with it.

But after running the Birkin for 5 years I wanted a new challenge and frankly a bit more comfort. I drive my car to and from events and in some cases that is a few hours away and doing so in the Birkin meant I was freezing cold in the morning and cooking in the afternoon on the way home. It was very very hot in that car and it had no doors or windows or top to speak of. It was a race car with plates - fast but very raw.

So when it came time to replace the Birkin I was looking for a car that was more civilized and comfortable but still very light and race car like. I tried a number of cars out before settling on the Elise. It took awhile to find one I could afford and I did eventually find one that needed some expensive-at-the-dealer work that I could do........so I got a deal on it.

The Elise is much heavier than the Birkin at 1900 pounds but still a good 1000 pounds lighter than many 'sports cars'. The fact that it has doors and windows and AC and heat really is nice during a 2 hour drive to or from the event. It's like a real car!

I've done a lot of modification to the car - wheels, tires, coilovers, swaybar, seat, supercharger...........etc. I've done 95% of the work myself. The only thing I had a shop do was to install a limited slip differential which requires the trans coming apart. While they were in there I had them install an alloy flywheel and and stronger clutch to deal with the power the supercharger brings.

My favorite thing to work on is the suspension and the alignment settings. I do all the ride height, cornerweighting, shock setting and alignment myself and I really enjoy doing this stuff. It reminds me of doing bike design and work.........very small changes can give very large rewards. After two seasons of tweaking it handles very, very well. This season I took my first state championship in this car and class (SCCA class - SSP) and have taken 6 FTD (fastest time of day) and 5 firsts in PAX (an handicapping system that allows drivers of much different cars to compare themselves driver to driver). It is so much fun I can't believe it's legal.

I raced last weekend and will race again the weekend after next. I'm already excited for the event I'll be doing next. Did I mention how much fun it is?

Dave

[William]

Dave,

Do you have a favorite way of joining tubes (I think the photos answer that question but I'll ask it anyway ;0 )? Fillet vs Lugged? Fillet would seemly require more work, other than that and aesthetics, what are the benefits of one over the other.






William

[David Kirk]

Originally Posted by William

Dave,

Do you have a favorite way of joining tubes (I think the photos answer that question but I'll ask it anyway ;0 )? Fillet vs Lugged? Fillet would seemly require more work, other than that and aesthetics, what are the benefits of one over the other.






William

Good question.

I don't know that I have a strong preference as I really enjoy doing both. In fact I like being able to go back and forth so I don't do the same thing all the time.

The biggest difference between the two, lugged and fillet, is aesthetic. There is no difference in ride, strength, or stiffenss and so little difference in weight that it's not worth considering. So it really comes down to the look. Lugs have a certain look of course and they lend themselves to certain types of paint schemes while fillets have a seamless organic look that works with a different type of paint scheme.

There is a different amount and type of labor and skill to do each. Shaping, brazing, and finishing lugs demands a certain skill set. There is a lot of fitting and refitting of the lugs to get the tube to lug fit just right. The labor time is more front loaded......meaning that the bulk of the labor time comes before the bike is brazed. Fillets on the other hand require only mitering the tubes before brazing and the bulk of the time is spent after the brazing is done. Kind of a six of one, 1/2 dozen of the other kind of deal...........except that it might be a 7 of one, 5 of the other in that it does take a bit more time overall to do good fillets than it does lugs.

On rare occasions fillets are chosen for pragmatic reasons - lugs have relatively narrow ranges of angles that they will work with and of course the tube diameters are fixed. Fillets can be used to join any shape or size of tube at any angle. So at times we will chose fillets because the best design for the rider and end use ends up being tough to do with lugs. This doesn't happen all that often but it does happen.

I just finished a fillet bike on Friday and will start a new lugged one on Monday.....love them both.

Vive la differance!

Dave

[soulspinner]

Your fillets are as good as I have ever seen. Thanks for all you do to help others on the forum. By the way,that Lotus is the poo. A guy at work autocrosses his type R. I think he installed carbon synchros as his took a beating. Is this the norm?

[David Kirk]

Originally Posted by soulspinner

Your fillets are as good as I have ever seen. Thanks for all you do to help others on the forum. By the way,that Lotus is the poo. A guy at work autocrosses his type R. I think he installed carbon synchros as his took a beating. Is this the norm?

Thanks - I really enjoy making the fillets look just right before the paint goes on. There are some bikes out there that really need the paint to make the fillets look good and while it does no harm really and the bikes ride and work fine I'm not a fan. So thanks for the comment.

As for the carbon syncros...........I've done nothing like that to my car. I wonder what that's about?

Thanks again and please let me know if you have any other questions.

Dave

[FlashUNC]

Originally Posted by David Kirk

Thanks - I really enjoy making the fillets look just right before the paint goes on. There are some bikes out there that really need the paint to make the fillets look good and while it does no harm really and the bikes ride and work fine I'm not a fan. So thanks for the comment.

As for the carbon syncros...........I've done nothing like that to my car. I wonder what that's about?

Thanks again and please let me know if you have any other questions.

Dave

Here's another dire, pressing question:

Greatest car ever made?

Can use whatever criteria you think appropriate.

[David Kirk]

Originally Posted by FlashUNC

Here's another dire, pressing question:

Greatest car ever made?

Can use whatever criteria you think appropriate.

More car questions that bike? Not that I mind talking cars mind you -

Here are a few thoughts on various cars. Not surprisingly they are Lotus related -

Best Street car ever -

This has to be the late 50's Lotus Elite (not to be confused with the less than desirable Elites of the 70's. This car is a cutting edge Tour De Force. It has a bonded fiberglass chassis and the only metal in it is the windshield hoop that runs over the top of the windshield and down each side to give the door hinges something to bolt to. Almost everything else is composed of fiberglass boxes bonded together. It weighed just a tad over 1400 pounds and was very quick in it's day with about 100 hp. On a winding road very little could stay with it and it got over 30 mpg. That and it may be one of the most beautiful car shapes every made.






Best sports car -

The car you save for Sunday blasts up highway 1, canyon runs first thing in the morning or for crushing all comers in an autocross. Originally designed by Colin Chapman of Lotus in less than a week and it's been in production for more then 40 years since. The modern versions are made by Caterham and Birkin but stay very close to their roots. They are as little car as can fit two adults and an engine and can give staggering performance. The car pictured is a modern Caterham version and will do 0-60 in less than 3 seconds and out corner everything else ever made. Raw, hot, loud, fun. Scary as ***** to use in everyday traffic as folks in camrys tower over you.






Best race car -

The Lotus 23B was a giant killer of epic proportions and put the 12 cylinder Ferraris to the rear using only a 1.6 L 4. Tubular space frame with an alloy body they weighed less than 1000 pounds in full race trim. Arguably the finest handling race car ever made. They were fast beyond belief in the turns and fast enough on the straights and they got such good mileage that they needed 1/2 the fuel stops of the other cars out there. Chapman was a smart man.






Best race car runner up -

The Lotus Eleven. 900 pounds of slippery. Nothing went as fast with so little power. They crushed at LeMans in the 'index of performance' being able to do 140 mph with a 1.1 liter engine. The aerodynamics were done by eye and trial and error by Frank Costin of Cosworth fame before he started Cosworth.






Honorable mention -

And last but not least and to show that I can see something other than Loti............the original Mini. Nothing even comes close to the brilliant packaging and performance that car had. Truly revolutionary.




I could go on for far too long. Time to get to the bench and make some bike stuff.

Thanks again,

dave

[FlashUNC]

I'd file the question under "tertiary relationship with bikes/framebuilding."

Just from following your work the past few years, it seems that ol' Chapman's philosophies play at least a partial influence in your thoughts on bike design.

Your rear dropout design, in particular, strikes me as something Colin might have done if he had picked up a torch to put bikes together rather than win Formula 1 and Le Mans titles.