How Did Odyssey Directors Break Frames?

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3/10/2017 8:45 PM

In another thread on Reddit a guy mentioned how he bought Directors new (Holy shit right? An Aussie website still has em), but mentioned that they broke headtubes off of frames. I've heard of this too, but this makes no sense to me, since the wheel is at the same place relative to the headtube and the force moves at the same angle. Anyone care to weigh in? I feel like people were just riding shittier frames.

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3/10/2017 9:13 PM

Haha I just saw that thread too


I've never heard of them breaking frames but I can definitely see how they could. They're definitely slanted forward more than traditional forks are, so that could add to it but the issue with the director forks was at the steerer tube/leg junction of the fork itself. I've seen SO many of them crack or break there.

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3/10/2017 9:26 PM

My hypothesis on the situation would be how the design of the fork sends the energy force from impacts directly towards the headtube. Traditional forks use a L shaped design, where the force of impact is more centered towards the right angle of the L, whereas the Director forks have the straight I shape, this sending the energy force from impact directly towards the headtube.

Essentially the forks are deaigned TOO well that they end up breaking frames.

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3/10/2017 11:20 PM

thairishguy wrote:

My hypothesis on the situation would be how the design of the fork sends the energy force from impacts directly towards the ...more

Seems like it's correct, it'd explain them cracking at the steertube-leg junction as well as the claims of them breaking headtubes.

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3/11/2017 8:21 AM

thairishguy wrote:

My hypothesis on the situation would be how the design of the fork sends the energy force from impacts directly towards the ...more

there is a difference in the load transfer between directors and refgular forks but it shouldn't break the headtube off.. there may have been a crack already or something that helped contribute to it other than just the design of the fork cuz otherwise this would be a consistently recurring problem. it sounds kind of isolated so maybe the failure was more unique to the frame than the kind of fork.

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3/11/2017 9:19 AM

thairishguy wrote:

My hypothesis on the situation would be how the design of the fork sends the energy force from impacts directly towards the ...more

I mean yeah but wouldnt the same amount of force be applied to the headtube regardless? I'm thinking of it like a lever; it doesnt matter if it's L shaped or a spiral or shaped like a dick, it should send the same amount of force to an axis.

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3/11/2017 6:51 PM

thairishguy wrote:

My hypothesis on the situation would be how the design of the fork sends the energy force from impacts directly towards the ...more

Super-Pawl wrote:

I mean yeah but wouldnt the same amount of force be applied to the headtube regardless? I'm thinking of it like a lever; it ...more

Direct versus indirect. Pretty much the same theory as taking two-cups-and-tight string method of transfering sound. If theres a kink in the string then the sound doesnt transfer to the other cup. The shape of the director sends way more energy to the headtube than a normal fork would.

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3/11/2017 11:09 PM

thairishguy wrote:

My hypothesis on the situation would be how the design of the fork sends the energy force from impacts directly towards the ...more

Super-Pawl wrote:

I mean yeah but wouldnt the same amount of force be applied to the headtube regardless? I'm thinking of it like a lever; it ...more

thairishguy wrote:

Direct versus indirect. Pretty much the same theory as taking two-cups-and-tight string method of transfering sound. If theres ...more

How? The front wheel is in the same place. They have the same amount of rake as another fork. On other forks with straight legs, the front wheel sits in front of the legs. The load transfer is the same, as the load is from the front wheel, which is still in the same place. If anything, this theory would mean the forks would bend/snap easier, not the frame

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3/12/2017 12:32 AM

grumpySteve wrote:

How? The front wheel is in the same place. They have the same amount of rake as another fork. On other forks with straight ...more

You're neglecting trail, and trail matters with respect to the force profile.

Hypothetical: Imagine a fork that when its legs exit the headtube, they angle backwards towards the BB, and [somewhat, at least] ape the angle of the downtube... let's just say. Given a sufficiently long "dropout", we could still maintain, well, any rake, but the force characteristics have completely changed.

Given the completely ridiculous fork I've described above, taken to its logical extreme, no one can say the force profile is the same simply because the front wheel is in the "same place" as some other fork-wheel combo.

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3/12/2017 1:36 AM
Edited Date/Time: 3/12/2017 1:42 AM

But the front wheel, and therefore any force travelling through the legs, is in the same position relative to the contact point between the forks and headtube. It doesn't matter what angle the legs are if the rake is the same, they could bend all over the place. But the impact on the headtube from the position of the front wheel is the same.

IF the legs had more rake, AND the dropouts where in the same place as traditional forks, your theory would be correct. But then they'd be a lot more offset, so it's not the same

Edit just to say, if the forks were snapping, your point would be relevant as the force would travel through the legs at a different angle (forcing them outward), but they're not

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3/12/2017 1:50 PM

grumpySteve wrote:

But the front wheel, and therefore any force travelling through the legs, is in the same position relative to the contact ...more

Given a force of magnitude X, and at angle Y, if you change the geometry of a system at any point, you've changed the force profile for the entire system, full stop.

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3/12/2017 3:22 PM

My theory is that the thin dropouts of normal forks dissipates a bit of the the force before it reaches the headtube.

The Directors have 10mm dropouts and much more force is directed(lol) towards the headtube area.

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3/12/2017 7:54 PM

Can anyone here do a finite element analysis of this? I think that's the only way we'll get a good answer to this.

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My Sunday Soundwave V3 Build
Insta: @p.gibbons

"You can't educate pork"
- grumpySteve

"Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside in a cloud of smoke, thoroughly used up, totally worn out, and loudly proclaiming "Wow! What a Ride!""
- Hunter S. Thompson

3/13/2017 5:23 AM

grumpySteve wrote:

But the front wheel, and therefore any force travelling through the legs, is in the same position relative to the contact ...more

GMGuinn wrote:

Given a force of magnitude X, and at angle Y, if you change the geometry of a system at any point, you've changed the force ...more

Yeah I get your point, it changes the force on the headtube. But also changes the force on the forks. I would've thought the forks would give out sooner, and if the forks are that strong, why aren't traditional forks made just as strong?

I genuinely think it's probably more of a case of a few occasions that have given the forks that reputation. Like some people hate profile cranks and think they snap easily just because they know of a couple of pairs that snapped, you know?

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