Tech Seat stays crossing seat tube ??

Apr 3, 2012
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Boso
#1
Can anybody tell me exactly what the advantages of a seat stay that crosses over the seat tube and connects to the top tube are?
Something like this:

I'm having a steel touring / randonneuring frame built by my friend (http://www.tunesaburou.com/) and he really wants me to do this. He tried to explain to me why this would be a good idea, but I didn't understand his explanation (my Japanese is passable but my bicycle Japanese has a long way to go). From what I could decipher it has something to do with the extremely tall (64cm) seat tube we will use. Aesthetically I quite like it and think I might do it anyways, but just curious if anyone can explain to me what the advantage of this is from a mechanical standpoint.
Oddly the only pictures of bikes like this I can find on the internet are older Japanese touring bikes... and BMCs.
 
Apr 3, 2012
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Boso
#2
A bit more Googling has revealed that these are called hellenic stays and that Sheldon Brown thinks they are "of no practical value". My builder friend disagrees.
 

jdd

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#3
No comment on the design stuff that you're referring to, but in the pic those are maybe the longest chainstays that I have seen. I have a touring frame with 450mm chainstays, and I'm just guessing from the pic, but it looks like those might be 480, or even more?
 

rommelgc

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#4
I can only share a link
You can also search the bikelist site

The Hellenic seat stay was invented by Fred Hellens in 1923, and was used by Thanet (1930s), Hetchins (about 75 in the late 1960s and early 1970s [Hetchins web site]), Colnago (1980s) and GT (1990s) among others.

The Hellenic stay arrangement, by lowering the angle of the seat stays, allows more vertical compliance and therefore a more shock absorbing ride than similar stays in a more vertical arrangement and the overlapping of the stays at seat tube and top tube limit/stiffen the side to side compliance (albeit to a small degree) making the bike frame climb and sprint with less side to side movement.

Yes, I have seen the Hellenic combined with the Curly on the Hetchins web site. Flash (Mr. Flash to you? ;) notes that, "The hellenic design was straight, but three odd-balls are known to exist. One has a curly hellenic triangle retro-fitted to a Vade Mecum. Another, shown here, is a one-off half-curly. A third curly-hellenic was special ordered in the late 1990s."
HTH
 
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FarEast

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#5
Gary Turner would disagree with Sheldon and to be honest I think Gary knows a lot more about bike building than Sheldon ever did.

The design is to reduce seat tube vibration which can increase the riders fatigue over long distance, especially on larger frames. So this design makes sense on a touring bike.
 
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kiwisimon

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#7
GT triple diamond used the same Hellenic design. You are buying the builders know how and philosophy, go with what he recommends or find another builder, but it makes sense as a means to stiffen up the rear end. There is a weight penalty but on a tourer that is not a factor. They do look cool especially if just the ST is painted in a contrasting color.
 
Apr 3, 2012
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Boso
#8
We talked about doing exactly that. Stays and lugs in white and everything else black. Can't wait to see it.
I think I'm going to give him the go ahead to start today.
 
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microcord

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#9
. . . From what I could decipher it has something to do with the extremely tall (64cm) seat tube we will use.
Have you considered, or did the man mention the possibility of, a double top tube? Rivendell does this for frames as large as yours will be. It's on the more expensive frames and on the cheapest (I think) as well. You get a fetishist/close look here.

There's a discussion here about a double top tube on a 56cm frame. There are intelligent comments pro and con; but it's "interesting" (slightly depressing) that the commonest can be summed up as "urgh, looks weird". One intelligent point is that it's a matter of the rider's weight: what's right for somebody weighing 120kg is unnecessary for somebody weighing 70kg. (Obvious when one thinks of it, of course.)

Incidentally, here's something interesting from Rivendell about top tube length (not doubling). Oh, and I'd thought that 64cm was tall too, but try 71cm.
 

GSAstuto

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www.roadfixie.com
#10
Here's a pic of a bike I made in the late 80's. I rode this extensively through UK, Europe and US. Also Raced it alot in CX. I passed it on to my friend who continued to ride it (and probably still is). What inspired me to do this? Nothing more than esthetics, actually. The thought did cross my mind that the saddle /seatpost region might be a bit stronger and perhaps a bit stiffer for climbing due the shorter effective seat tube. As far as compliance goes - I'd venture to say you feel more in a few psi airpressure unless the bike is really loaded down. And unless the stays are curved to transfer load in a more non-linear way, you certainly don't want too much flex at the brazed ends. They will work harden and eventually crack and fail.



You can't see it in the pic - but I used a Sanyo BB dynamo which was very avante guard at the time..
 
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bawbag

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#11
Also a love for Van Halen from the looks of things!
Here's a pic of a bike I made in the late 80's. I rode this extensively through UK, Europe and US. Also Raced it alot in CX. I passed it on to my friend who continued to ride it (and probably still is). What inspired me to do this? Nothing more than esthetics, actually.
 

bawbag

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#13
Who copied who? That motif was pretty popular in the 80's. I can say for certain that VH was not included in my list of influences (musical or otherwise). I was more into Cabaret Voltaire, Husker Du, Flipper, Minutemen, Damned, Pere Ubu, etc..
In which case I salute you on your excellent musical taste.
 
Apr 3, 2012
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Boso
#15
Have you considered, or did the man mention the possibility of, a double top tube? Rivendell does this for frames as large as yours will be. It's on the more expensive frames and on the cheapest (I think) as well. You get a fetishist/close look here.

There's a discussion here about a double top tube on a 56cm frame. There are intelligent comments pro and con; but it's "interesting" (slightly depressing) that the commonest can be summed up as "urgh, looks weird". One intelligent point is that it's a matter of the rider's weight: what's right for somebody weighing 120kg is unnecessary for somebody weighing 70kg. (Obvious when one thinks of it, of course.)

Incidentally, here's something interesting from Rivendell about top tube length (not doubling). Oh, and I'd thought that 64cm was tall too, but try 71cm.
As practical as it may be I just can't get behind double top tubes. Call me shallow, but I want a sporty bike that looks like what I think a sporty bike should look like. Where the seat stays just look a bit quirky, a double top tube just looks wrong (in my humble opinion).

Incidentally I have a freakish 94.5 cm inseam (at only 188 cm tall:eek:(CUSTOM FRAME PLEASE!)), which would put me on at least a 67 cm Rivendell according to their sizing chart. I quite like their philosophy and was partially inspired to build this bike by it, but I'd like to have a bit of bar drop for when I'm feeling feisty, and then the ability to bring the bars up with a tall stem when I want to ride grandpa's touring bike. I'm planning on using Nitto's super tall Technomic Deluxe stem, which will give me the ability to bring the bars up quite high if I feel like it. I think in general I will leave about 6 or 7 cm of drop though. I've been riding 57 cm bikes with 13 to 15 cm of drop for the last few years, so that will be a quite pleasant change.



View attachment 367

You can't see it in the pic - but I used a Sanyo BB dynamo which was very avante guard at the time..
Love that bike. Also good to see Minutemen fans around! I always thought cycling was the most punk rock of all sports.
 
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kiwisimon

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#17
We talked about doing exactly that. Stays and lugs in white and everything else black. Can't wait to see it.
Sounds great but try on a piece of paper different color combinations, you still have a heap of time. . Try the above with an all white seat tube versus an all black seat tube and see what floats your boat. Black and white are a great combo though.
 

FarEast

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#18
Sounds great but try on a piece of paper different color combinations, you still have a heap of time. . Try the above with an all white seat tube versus an all black seat tube and see what floats your boat. Black and white are a great combo though.
Agreed and go with any highlights such as coloured bar tape with matching cable housing etc.
 

microcord

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#20
. . . I'm planning on using Nitto's super tall Technomic Deluxe stem. . . .
Although it's not mentioned on Nitto's website, Nitto (or its wholesaler) also has some (front-to-back) sizes of an equally tall version of the "Dynamic" stem (I think it's called), which is made of a classier alloy and looks a bit more swish than the TD. (I know because I was going to get a TD from HiRoad; then Aoyama-san learned of the Dynamic; but then in the end we got a stem that wasn't so tall.)

Remember that there's an awful lot of Technomic Deluxe (or Dynamic equivalent). Will you be able to have that "bit of bar drop"? (Will you be able to push enough of it into the head tube?)