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  1. #1
    bpuodt
    Reputation: Robot Chicken's Avatar
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    Horst evolved to near useless. How do we get it back?

    As you guys know, the horst link used in most of today's bikes is pretty damn close to the axle, thus not much of a difference in wheel path compared to a similarly placed single pivot 4 bar. The only advantage would be the braking correction made by the Horst link.

    In fiddling with linkage 2.5, I've found that putting the Horst pivot forward more than halfway between the axle and BB and lower, made for a much better axel path. I've found it to work well when placed near the rear rim at around the 4 o'clock area. When setup like this, it achieves a axel path and pivot point similar to a Canfield Formula 1. Unlike the Canfield, the modified horst allows for a chain guide to be mounted above and behind the BB closer to the desirable chain line. In this form, the rear wheel can travel rearward over 15mm with a near symetrical arc, while still maintaining a chain pull range of only 3mm.

    In this case, the horst pivoted bike will still pedal very well and brake fairly well, but at least have a decent rearward axel path for DH. My only complaint of my horst pivoted bike is that the axle path isn't the smoothest on harcore DH sections, even though it still pedals well through nasty stuff.


    Is this what the original Horst was designed to be? Has the pivot been moved back and up ONLY to prevent chain and derailleur slap?

    I'm still looking at ways to get the chain by the horst pivot when lower and near the wheel rim.


    Any thoughts?

    Mind you I'm using the linkage demo, so no images. Here's a crappy drawing, Mind you rocker plate is not exact. Just showing linkages.
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  2. #2
    Buckle Up
    Reputation: WheelieMan's Avatar
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    If the Horst-Link was moved more than halfway between the axle and pivot, I don't think it would qualify as a Horst-Link anymore. That brings up an interesting question... How close to the axle and at what angle must the pivot be in order to be considered a Horst-Link?

    In my opinion, the Horst-Link has never provided an advantage as far as wheel-path. If you want a rearward wheelpath without insane amounts of pedal feedback, the only way to do so is with the chain rerouted.

    I feel that more neutral braking is the only advantage of the Horst-Link. The orientation of the top-link is much more important IMO than the placement of the Horst-Link. For example, designs such as the 05 Specialized Enduro have the top link placed at such an angle that the Instant Center is basically in "single-pivot territory." In other words, the Enduro would perform almost identically if it had a seatstay pivot instead.

    I'm not following your diagrams. They just look like Cs to me.
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  3. #3
    The Ancient One
    Reputation: Steve from JH's Avatar
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    If I'm following the diagrams, you would have an enormous extending torque with every pedal stroke, in any gear. Also a huge amount of pedal feedback. As Wheelieman suggested, that's why bikes like the Canfield have a redirected chain.

    To Wheelieman, I see some pedaling advantages to the HL.

    Normally if the traction holds, there is a compressive element to the moment created by the chain acting on the wheel/swingarm unit that is exactly cancelled by an extending element created by the ground force acting on the wheel/swingarm unit. What's left to affect the suspension is simply the angle of the chain relative to the angle of the swingarm. But when traction momentarily disappears (which probably happens much more often than we realize in real Mtb conditions) the ground force disappears but the chain force doesn't. The compressive element to the chain force that was previously cancelled now suddenly goes into the suspension. This element depends on the exact location of the IC, just as with braking.

    The result is that a Turner HL and an otherwise identical TNT would behave differently at the instant of traction loss. A small slip will turn into a bigger one.

    This is all supported by stuff in the Cossalter motorcycle book I have been studying.

    I have another theory, more or less my own, that a more forward IC may cause less loss of kinetic energy when the rear wheel hits a bump. This wouldn't have anything directly to do with pedaling. I won't go into it further now.

  4. #4
    Buckle Up
    Reputation: WheelieMan's Avatar
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    Quote Originally Posted by Steve from JH
    If I'm following the diagrams, you would have an enormous extending torque with every pedal stroke, in any gear. Also a huge amount of pedal feedback. As Wheelieman suggested, that's why bikes like the Canfield have a redirected chain.

    To Wheelieman, I see some pedaling advantages to the HL.

    Normally if the traction holds, there is a compressive element to the moment created by the chain acting on the wheel/swingarm unit that is exactly cancelled by an extending element created by the ground force acting on the wheel/swingarm unit. What's left to affect the suspension is simply the angle of the chain relative to the angle of the swingarm. But when traction momentarily disappears (which probably happens much more often than we realize in real Mtb conditions) the ground force disappears but the chain force doesn't. The compressive element to the chain force that was previously cancelled now suddenly goes into the suspension. This element depends on the exact location of the IC, just as with braking.

    The result is that a Turner HL and an otherwise identical TNT would behave differently at the instant of traction loss. A small slip will turn into a bigger one.

    This is all supported by stuff in the Cossalter motorcycle book I have been studying.

    I have another theory, more or less my own, that a more forward IC may cause less loss of kinetic energy when the rear wheel hits a bump. This wouldn't have anything directly to do with pedaling. I won't go into it further now.
    Yeah, I'm aware of your theories, but quite frankly, I don't buy them. I do appreciate you bringing them forth though... This theory and Cossalter's anti-squat calculation method seem to be contradictory. What am I missing? I will explain where my confusion results later, I need to leave at the moment.
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  5. #5
    bpuodt
    Reputation: Robot Chicken's Avatar
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    Quote Originally Posted by Steve from JH
    If I'm following the diagrams, you would have an enormous extending torque with every pedal stroke, in any gear. Also a huge amount of pedal feedback. As Wheelieman suggested, that's why bikes like the Canfield have a redirected chain.

    .
    Well, as I mentioned, it would need a chain guide roller above and behind the BB a ways. Without the chain guide, it's going to have over 30mm of pull in 160mm of travel.

    I managed to place the chain guide in a perfect spot on the main traingle. Chain pull reduced to about 3mm in any gear.

    Main problem with what I showed is the fact that the chain will hit the horst pivot. I guess this is why both DW and Canfield put this link further up and forward, out of the way.

  6. #6
    The Ancient One
    Reputation: Steve from JH's Avatar
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    Quote Originally Posted by Robot Chicken
    Well, as I mentioned, it would need a chain guide roller above and behind the BB a ways. Without the chain guide, it's going to have over 30mm of pull in 160mm of travel.

    I managed to place the chain guide in a perfect spot on the main traingle. Chain pull reduced to about 3mm in any gear.

    Main problem with what I showed is the fact that the chain will hit the horst pivot. I guess this is why both DW and Canfield put this link further up and forward, out of the way.
    I'm sorry. I missed the part about a chain guide. My bad.

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