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  #1501  
Old 03-20-2020, 07:00 PM
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David Kirk David Kirk is offline
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Originally Posted by gbcoupe View Post
Such a tease. Uhm... yeah, that one looks my size and I'll take the roaster too!
I'm going to need the roaster come Thanksgiving....sorry

dave
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  #1502  
Old 03-20-2020, 07:18 PM
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David Kirk David Kirk is offline
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A virus shortened ski season has made me wish for nice enough weather for a ride or two. Today my wish came true and it was 43 degrees, sunny and calm. Not bad for March in Montana.

Stay safe out there.

dave
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  #1503  
Old 03-21-2020, 06:31 PM
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572cv 572cv is offline
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It was sunny and not-quite-that-warm here.... so I wussed out and did chores and prepared a slow stew for dinner. But you have inspired me: tomorrow is supposed to be a hair warmer, and dry, so, out we go.

Your note about short wait times has me thinking about my bike in SS. Stay healthy out there!
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  #1504  
Old 03-24-2020, 02:13 PM
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David Kirk David Kirk is offline
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Is Fork Tip Tuesday a thing? Well it is now I guess.

Slotting fork blades to fit the tips and brazing them is something that many have trouble picturing but in reality it’s simple if not fussy.

I think you can see the progression from marking where you want to slot the blade, to the two hacksaw slots, to bending away and breaking off the tab. It’s then filed to the perfect fit and the ends are beveled and the tip is dry fit into the slot. Then it’s a simple matter of cleaning, fluxing, brazing and finish work....and suddenly you have a fork tip that will be light and stiff and last a lifetime. Easy peezy.

I have no idea how many times I’ve done this since 1989 but it’s a big ass number.....10,000ish times would be a rough guess. I can certainly do it in my sleep or while singing along to the Dead Milkmen’s Bitch’in Camarillo at 11.

Muscle memory can be a good thing.

dave



















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  #1505  
Old 03-24-2020, 02:19 PM
Clean39T Clean39T is online now
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Originally Posted by David Kirk View Post
Is Fork Tip Tuesday a thing?
If it isn't, it should be.. Thanks for sharing. I love the fork on my MRB - knowing what it looked like before and during just makes me appreciate it that much more..

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  #1506  
Old 03-24-2020, 02:43 PM
bob heinatz bob heinatz is offline
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Great pictures Dave. I still marvel at how simple but elegant my Kirk frame is.
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  #1507  
Old 03-31-2020, 04:49 PM
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David Kirk David Kirk is offline
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I was asked the other day about my Triple F Dropouts. The guy said something like “What’s the deal with those drops?” and I wasn’t sure what he was asking. In the end the real question centered around the design and how they are built into a frame.

My main focus when designing the Triple F (stands for Form Follows Function) was to simply make the smallest, stiffest, strongest and most easy to work with dropout that exists. Should be easy.

The design centers around the machined balls that will sit into the stays at any angle without having to slot the stay. The process of building with them is simple. First I make rings of filler material that get pressed into the ends of the beveled stay. It then gets fluxed and brazed and finally they get cleaned and shaped and polished shiny. I like shiny.

You can see just how simple it is in concept. It ends up being lighter and stiffer and stronger than anything else out there. Can you tell that I’m proud of them?

The Kirk Triple F’s go into most every bike I build and it’s been that way for many years now.

Thanks for reading.

dave











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  #1508  
Old 04-01-2020, 10:42 PM
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sw3759 sw3759 is offline
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thanks for sharing Dave.wasn't sure how you put those together either.,such an elegant look,sure wish my terraplane had those but not sure it feel any different but they are certainly are beautiful !
also curious if you ever played with the idea of hooded dropouts and what your thoughts on the pros and cons of that design? quick release positioning is the only drawback that i have encountered but that depends on QR design too.but maybe you just dislike that look on your frames



also what ever happened to your flat crown forks?

Last edited by sw3759; 04-01-2020 at 10:47 PM.
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  #1509  
Old 04-02-2020, 07:19 AM
Peter P. Peter P. is offline
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Re: the fork dropouts.

How do you know how much to cut off the legs so when adding the dropouts you arrive at the fork rake you're aiming for?

Seems to me that cutting the fork legs to the same length would not be an exact science, particularly when using hand tools, and the fact the leg is curved would complicate things.
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  #1510  
Old 04-02-2020, 08:05 AM
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kiwisimon kiwisimon is offline
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Not trying to steal Dave's thunder but this might explain things.

http://kirkframeworks.com/2011/02/01...meset-part-iv/

The whole "process" section is a great resource.

I've been stalking Dave's website for about over a decade now. Great reading.
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  #1511  
Old 04-02-2020, 10:11 AM
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David Kirk David Kirk is offline
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Quote:
Originally Posted by sw3759 View Post
thanks for sharing Dave.wasn't sure how you put those together either.,such an elegant look,sure wish my terraplane had those but not sure it feel any different but they are certainly are beautiful !
also curious if you ever played with the idea of hooded dropouts and what your thoughts on the pros and cons of that design? quick release positioning is the only drawback that i have encountered but that depends on QR design too.but maybe you just dislike that look on your frames



also what ever happened to your flat crown forks?
Good Morning -

I used a Wright style (hooded) dropout on some of the first JK Specials and they were OK. I didn't like the issue with too many QR skewers not fitting well and I had complaints about that.

From a building standpoint Wright dropouts are a real PITA. Both the c-stays and s-stays require offset compound (two angles) miters to fit. Life's too short to spend time trying to get all four miters perfect when in the end there's no upside.

The other issue with Wright drops is that "H tooling" them is very tough. One uses H tools to make sure that the dropout faces are parallel and concentric and getting it perfect is almost impossible. In many cases the builder doesn't even try and they just hope that the dropout face alignment comes out right out of the jig because cold setting them is so frustrating.

The Triple F drop requires no fussy offset, dual angle miters but instead they are square cut and this saves a huge amount of time and doesn't impart a 'pull' when brazing so once they are brazed in the jig H tooling becomes moot...but if you need to move them you can.

For me the Wright style are mostly downside and almost zero upside.

Flat crowns - I've found over time that a curvy semi-sloped crown just looks right to my eye with the more modern lugs shapes that I favor. Combine that with the extra weight they usually bring and it was a done deal for me.

dave

Last edited by David Kirk; 04-02-2020 at 10:31 AM.
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  #1512  
Old 04-02-2020, 10:28 AM
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David Kirk David Kirk is offline
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Quote:
Originally Posted by Peter P. View Post
Re: the fork dropouts.

How do you know how much to cut off the legs so when adding the dropouts you arrive at the fork rake you're aiming for?

Seems to me that cutting the fork legs to the same length would not be an exact science, particularly when using hand tools, and the fact the leg is curved would complicate things.
Hey - very good question. Getting the finished length of the blade/dropout assembly just right is fussy.

I take my curved blade and determine how much to cut off the small end so that when the drop is brazed in it will have the proper amount of rake. I have a tool of my own design that makes this very simple. Set the desired rake on the tool, place the blade in, make a sharpie mark and cut it off.

The blade is then slotted and the tip is brazed in. Once that is done I can figure out the final length of this blade/tip assembly. I have another tool that allows me to hand cut the blade off slightly long (typically about .020" long) and then it is ground to the exact length and placed in a go-nogo tool to be sure that both blades are the same length.

They can then be brazed into the crown with the assurance that they are the same length and that the fork with be straight.

Does that make sense? I've never typed out that process before.

dave
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  #1513  
Old 04-02-2020, 10:30 AM
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David Kirk David Kirk is offline
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Quote:
Originally Posted by kiwisimon View Post
Not trying to steal Dave's thunder but this might explain things.

http://kirkframeworks.com/2011/02/01...meset-part-iv/

The whole "process" section is a great resource.

I've been stalking Dave's website for about over a decade now. Great reading.
Wow - blast from the past! I made that post in 2011 - it's good to know it's still looked at.

dave
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  #1514  
Old 04-02-2020, 09:16 PM
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sw3759 sw3759 is offline
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thank you Dave for taking the time to explain your decision and that process in so much detail.
i did recall our initial build conversation years ago and you convinced me the semi sloping was the way to go with the webbed lugs you built mine with and i was on the fence re the crown.


Quote:
Originally Posted by David Kirk View Post
Good Morning -

I used a Wright style (hooded) dropout on some of the first JK Specials and they were OK. I didn't like the issue with too many QR skewers not fitting well and I had complaints about that.

From a building standpoint Wright dropouts are a real PITA. Both the c-stays and s-stays require offset compound (two angles) miters to fit. Life's too short to spend time trying to get all four miters perfect when in the end there's no upside.

The other issue with Wright drops is that "H tooling" them is very tough. One uses H tools to make sure that the dropout faces are parallel and concentric and getting it perfect is almost impossible. In many cases the builder doesn't even try and they just hope that the dropout face alignment comes out right out of the jig because cold setting them is so frustrating.

The Triple F drop requires no fussy offset, dual angle miters but instead they are square cut and this saves a huge amount of time and doesn't impart a 'pull' when brazing so once they are brazed in the jig H tooling becomes moot...but if you need to move them you can.

For me the Wright style are mostly downside and almost zero upside.

Flat crowns - I've found over time that a curvy semi-sloped crown just looks right to my eye with the more modern lugs shapes that I favor. Combine that with the extra weight they usually bring and it was a done deal for me.

dave
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  #1515  
Old 04-03-2020, 07:28 PM
Peter P. Peter P. is offline
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Quote:
Originally Posted by David Kirk View Post
Hey - very good question. ...
Does that make sense? I've never typed out that process before.

dave
Yes it does! I always wondered whether the forks come long enough to trim both ends.

It was also my understanding that you could buy pre-raked blades if you didn't or couldn't rake them yourself. There is definitely an aesthetic aspect to the radius of the curve, and the beauty is in the eye of the builder or the customer, take your pick.
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