Stretch Build

OK I have admired Augidog's stretch frame since I joined. I have been wanting a Surley Big Dummy for even longer. So now I will build one for me.

Today I cut into a perfectly good Diamond Back Apex full double butted Cro Moly frame. datz510 was kind enough to let me buy this off him for what he paid on Saturday $30 on Craigs List. The parts mostly will be replaced, but the frame is solid with a ding or 2 , and now 4 pretty serious cuts. Oh yes I am waiting now on a GEBE kit with a Tanaka 40 that should power it nicely.

I will try to show what I am doing as I do it. I hope to mount fairly low at say a 45 degree angle forward and make use of the space created between the wheel and the seat tube. The main piece to extend the frame is a tandem tube I have been sitting on for 10 years. I will braze the frame back together with pieces cut and mitered to fit.
 

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lennyharp

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Apr 17, 2008
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rough draft

This is where I just get ready to fill in the blanks. I will make a drawing of exactly what I want so I can cut and miter tubes to fit. I may get a board to do the drawing as this is too short er ugly. Gotta have a clean slate to get the ideas right. This is good for the rough draft though. Augi warns not to get too long so I am a little shorter than Surley's Big Dummy frame.

Here is a photo of one of their bikes. Only costs a grand or so, without the parts. They are a cool company and provide the geometry of the frame here http://www.surlybikes.com/bigdummy.html
 

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lennyharp

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Apr 17, 2008
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Here is the rough draft I mentioned. This is to see if what I have will work or if I need to make changes. I can see one for sure and that is the fork. It has too much rake and I will want to change it out for one with less the trail is over 2 1/2 inches and I would like it under 2. It could be I drew it wrong so I will try that part again. Also I did not measure the head angle but did measure the seat angle. The head angle is more important and since I am working with a fixed front I need to redraw with that angle fixed, and the other will fall where it may.
 

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augidog

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Apr 20, 2008
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lenny...

when we chopped s-2, we started by jigging the front of the frame at its' original angle...the rest "wrote itself" :cool:

while it's on my mind...my chain-stay extensions are double-walled tubing, fully weld-penetrated thru both thicknesses.
 
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lennyharp

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Apr 17, 2008
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I have always wanted jigs but never built or paid for them. What I will show is the ways I have used to build bikes, and hopefully 1) it rides nice and as planned & 2) some other underfunded home mechanics don't let a lack of tooling stop them from trying some ambitious projects.

Not having all the equipment another has is not reason to avoid a project. You just need to study what is done to get a finished project and develop some ways of getting it done. Lacking jigs I am showing a very effective way of getting the angles right and alignment is another issue I deal with also.

I used to go to the local frame builders and try to pry experience and advice from their closed mouths. They rarely let much info slip so I could more quickly learn the ways of building great bikes and accessories. This closed information system may be the ways of the industrial revolution where you had to apprentice to learn, but I think we are moved on to the information age where truth and techniques can be discovered more easily.

Now developing the skills to make the information work is another thing altogether. We can at least share info and experiences and the skills will develop in trying things out. Hopefully in this sharing exercise I will more fully develop my frame building skills. I wish I had a record of some of my other builds from the 1980's and early 1990's.

I see Zomby Builder posted this previously. http://www.motoredbikes.com/showthread.php?t=8495
 
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augidog

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Apr 20, 2008
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a long "8-by" board is all that's needed, "hilti" it to the garage floor or clamp it to a nice surface...build a riser in the front for the forks/axle, a riser mid-point for the bottomset, some washers and bolts to hold it there, then calculate length, set a riser (even-height with the front) where the rear axle will be, fill the gap...

only trying to shoot ideas at you, anything to make it easier, eh?
 
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datz510

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May 9, 2008
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Lenny, as we say on a 4x4 truck board about tube cages "Needs more triangulation!!" ;) Just ribbing you, my friend.

I added a couple more members to the frame drawing for good measure.
 

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lennyharp

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Suspension fork

Ideas are good. This forum is built on ideas. Triangulation is good too. I am leaving that area open untill I decide where the motor goes. As low as possible without having heel clearance issues.

Anybody have a suspension fork for a 1" steering tube? After riding for a couple of hours I decided I really should have suspension stuff on this bike. I really love the way my other Diamond Back rides. It is my first bike with suspension anything and now I have about 1000 miles on it and don't know how I rode those other 99,000 miles without it.
 

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