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Discussion Starter · #1 ·
Hello.
I am very new to the art of frame building... although I do bring physics, mechanical, and sculptural precepts to the tray.
With the help of a wonderful open source drawing program, I sketched up a frameset
which has quality's I feel past owned cycles have been missing.
My body's shape is a bit odd, meaning that my upper is quite light compared to lower. So when sprinting, climbing, or max rpm'ing', I really run into issues with frame-sway loaded or unloaded in the saddle.

The odd geo is closer to the 'triple triangle' in that its side to side strength would hopefully be much stiffer then a standard 2 triangle design.

I am seeking experienced insight on whether taking the 3-tri further is a good/bad idea: lengthening (possibly enlarging the dia./draw) the seat-stays to reach almost midway on the top tube. The pair would have joints on the seat-tube which would nill having to attach a brake bridge (making it disc, front, or fixed cog only).

[lugs are not specific]

If I am way off on this sketch, please recognize I am just a curious fellow whose interests run high.

Thanks in time!

truly,
jmk
 

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whoa that looks weird. I'm not the fount of knowledge that some people are on here are, just a huge rider, but my experience is that the triple triangle set up does more to make the ride harsh than it does to keep the frame from swaying under power. A big downtube and large diameter beefy chainstays with a brace close to the rear wheel does a better job of keeping it all together. What's up with the wacky geo?
 

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If you want a stiffer frame use larger diameter tubes and keep the front triangle small/tight.
 

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What you call a triple triangle frame has been around a long time and is a proven design. They are often called "Hellenic stays" in honor of Fred Hellens who made frames that way in England in the 1920's. I saw this style for the first time in a "Bicycling" article in 1969 in a review of the British Hetchins frames (Hetchins is well known for its curly stays and fancy lugs <www.Hetchins.org>). Bicycling magazine was called "American Cyclist" then. GT built their bicycles that way some time ago (before the original owner died in a motorcycle accident) and even before that Nashbar frames had Hellenic stays. Some Shogun frames did this for awhile, too. I made myself a personal bike using this seat stay attachment style. Hank Folson wanted me to have a frame in his Henry James booth for Interbike years ago and I chose that way partly because it shows off the seat lug better without any attachments going to it.

I should add that when I've made frames with "Hellenic" stays I thought something good was going on. I can also say that I'm not too crazy about the looks but it does triangulate the frame more. This would seem to be a bigger advantage on bigger frames. I would describe the feel as being more vertically compliant and laterally stiff (the ultimate praise in a bicycle magazine review whether or not it is true). I am not a mechanical engineer (my degrees are in education) so my impressions are just a seat of the pants feeling. The first time I rode one, it was a customer's frame I painted that was built by Cyclery North in Chicago (that has long gone out of business). I was expecting that the hype was just visual marketing and I wouldn't be able to tell the difference but was surprised to be very favorably impressed. I've made maybe 10 of them in my 35 years of building frames. They have been well liked by those customers.

If your seat stays are attached as far onto the top tube as your diagram, then it is likely the back of your thighs will be banging uncomfortably into them. That is why you don't see them going too far forward.

Doug
 

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doug fattic said:
They are often called "Hellenic stays" in honor of Fred Hellens who made frames that way in England in the 1920's.
Thank you Doug!!

Better to use the right terminology than a modern advertising name. "Triple Triangle" is right up there on my peeve meter along with "Gooseneck"

I believe this treatment on this frame is too extreme. For the reason you mentioned and the fact that neither the ST or TT is butted at all in this area. It's asking for a future failure.

We have no geo on that page, so kind of hard to tell you much of anything.
 

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Discussion Starter · #8 ·
Awesome shared knowledge guys.
I am particularly blessed with the opportunity to hear Doug and Bohm's thoughts shortly
after discovering their custom build works.

Beautiful stuff dudes! Thanks for the springboard to learn some more with the terms too!

I might bounce back a different layup in a couple days just to see your thoughts. If you get a chance, please break the levy and flood my mind with more insights.
!

truly,
jmk
 

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Discussion Starter · #9 ·
my fault on the lack of knowledge difference between advertised and terminology.

That too is something I am not a fan of in other arts... so I'm feeling ruff there.

Thanks for the correction.

jmk
 

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Discussion Starter · #11 ·
well...
I have done a bit of learning, (never enough) and decided to redraw the sketch crowning this post.

I feel it builds on criticisms such as:

-raised intersection of seat-stay/seat-tube bridge
-smaller front triangle
-seat-stay rake matching fork (50mm)
-'almost' parallel seat-stay and bottom tube

Any thoughts on the seat-stays acting as a static shock like the fork does?

Thanks again!

truly,
jmk
 

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If you use a narrow q-factor, the riders legs will rub against the seat stays!
If you want "static shock" turn the seat stays the other way around...
 

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I'm not a frame builder (yet) but enjoy reading these threads and picking up knowledge for the future. Can some one fill me in on how this is hour-glass geometry? I fail to see the connection.
 

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Discussion Starter · #15 ·
That title only stemmed from my beginning knowledge (or lack thereof) of the term to describe seat-stays that overlap the seat-post and make a connection on the top-tube.

That wording arose from the first sketch posted here where the area below the saddle resembles two (almost) equilateral triangles end on end. Much like the silhouette of the two chambers in an hourglass.

(thank you guys for enlightening me) The historical way they have named this is 'Hellenic Stays' for the innovator if I understand right.

jmk
 
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