So I was debating the merits of triple triangle frame geometry with a colleague today.
He said he didn’t like it as it was just an aesthetic feature, where I countered (for the sake of an argument) that it produced a stronger frame and therefore lighter tubing (yeah, I’m full of shit.)
Although GT TT frames were notoriously heavy, (so the internet tells me.) But track TT frames are probably a different story.
So does it just look cool? Or was it born out of a structural/geometric consideration?
My old man got into framebuilding in the late 70’s, when supposedly there weren’t many photos of bikes on the internet. After a few test frames he built all almost all his frames as triple triangles. I remember him explaining the rationale to me as a kid - the seatstays are made shorter, and running the stays past the seat tube increases the depth of the structural system in the direction of the forces to be resisted, i.e. laterally. The “back span” of the stays between the seat tube and the top tube also allows slightly thinner chainstays, which in combination with the shallower seatstay angle gives better vertical compliance.
According to some the combination of lateral stiffness and vertical compliance results in some sort of ecstatic pleasure whilst riding, though I’m yet to reach that level of nirvana myself.
I’ve also heard the idea referred to as “equilateral stays” - I assume because with some geometries, the chain stay, seat stay and seat tube form an equilateral triangle, which is probably equally useful in forming cult-like geometric symbols.
A frame design in which the seat stays don’t go to the seat cluster, but rather cross outside of the seat tube a few inches below the seat cluster, then go on to be attached to the top tube a few inches forward of the seat tube.
Hellenic stays were introduced by (and named for) the British frame builder Fred Helens in 1923, and have been used off-and-on since by frame builders who wish to make their frames visually distinctive. They are of no practical value, and often cause un-necessary complication in brake-cable routing, luggage-rack attachment and installation of frame pumps. The are also slightly heavier than normal frame construction.
Recent users of this design include GT, Huffy and Nash bar.
Makes sense that the rear triangle would be stiffer laterally. Probably born out of a situation like this:
Framebuilder grub 1 - “a triple triangle might be stiffer”
Framebuilder grub 2 - “triple triangle showz off mad braz’n skillz”
Framebuilder grub 1 - “bugger it lets do it”
I actually think the triple triangle frames are the bizniss.
Aren’t old french tourers triple triangle as well?
a) style
b) dropouts were not always available in different angles and builders were just following the lines dictated by whatever angle was cast into the dropouts at hand (small and large frames will often necessitate different dropout angles, you can rotate the dropout to some extent but brazing a stay at too sharp an angle will lead to a stressed joint and more chance of failure)
c) style
Okay, so now I’d like to bring in my star witness, Brendan, who recently got a TT* Bundy made for him.
So how did that come to be, did the client or builder request it? Was it deemed to be stronger/lighter/heavier/faster or just look sahweet?
A response really depends on Brenno reading this thread…
In this thread I’m using TT as an abbreviation for triple triangle, not time trial, targa trophy or top tube. I’m sure you already worked that out, but I thought I should clarify.
I’ve never liked them. Remind me of over-engineered K-Mart mountain bikes, especially given that a lot of them you see are called GT’s in similar K-Mart vain. Didn’t all kids want the one that said GT, if you know what I mean?
some will join at the seat collar/binder bolt area (Cinelli), some will join well down the seat tube like the above (and in a Raleigh’esque style). fastback stays - Google Search
isn’t the fastback terminology used more in relation to the positioning of the join of the seat stays to the seat tube, in regard to side mount/rear mount (ie, fastback being mounted to the rear of the seat tube/less frontal area etc) is this correct?
I’m talking specifically about the “triple triangle without the extra triangle” shape… is that still defined as just “fastback”? i’ve been curious about this for a while
Some call these different but I think they’re much the same except for where they attach. Splitting hairs.
Of course my opinion isn’t the only one and the below link classifies the different approaches as fastback, shot-in, and itallianate seat stay attachment styles. Hetchins curly stays, vibrant stays, hellenic stays
Anyway, I’m in trouble now. Mrs. Spirito says that it’s late, my keyboard tapping is too loud and I have to switch off the computer and the football I’m watching on TV and go to bed.
