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  1. #1
    Toro
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    Drawbridge for bikes.

    Has anyone seen a bike actuated drawbridge? I was just wondering if more creative individuals have ever come up with a bridge that can be actuated from either end by a bike riding onto it. Thanks.

    The best I can come up with is two teeters attached with a pulley system.
    Ricardo aka "El Toro"
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  2. #2
    Hermit
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    I almost hate to ask...

    Are you talking about a bridge that would be up, then as you rode on it would descend to normal bridge position?

    That could be done, but it would be easiest if it was one directional travel. Two directional would take extra work for sure.

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  3. #3
    Toro
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    Yes! We are being ambitious. Unidirectional is easy. Bidirectional is a bit more work. I have a solution but i wanted to probe the community as well. I'll post what i have in mind when i get home. Thanks.
    Ricardo aka "El Toro"
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  4. #4
    Stiff yet compliant
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    Here is something I came up with on the fly. Should be fairly simple to build.
    Why do you need a draw bridge anyways?
    Attached Thumbnails Attached Thumbnails Drawbridge for bikes.-bridge.png  


  5. #5
    Toro
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    Excellent! Thank you. I'll post mine as soon as I can.

    I don't need a draw bridge. It was an idea a friend had. I'm just trying to solve the problem. We figured it would be a cool entrance to a skills section of trail.
    Ricardo aka "El Toro"
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  6. #6
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    why not tie the teeters together on one end? no pulley needed. Maybe I am not understanding the end goal....

  7. #7
    Toro
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    All ideas are welcome. Sketches are appreciated. There is no wrong way of doing this. We just want the least amount of moving parts. My idea falls along the lines of what was posted above minus the pulleys.
    Ricardo aka "El Toro"
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  8. #8
    Stiff yet compliant
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    Here is another one. Attach chainrings to both bridge pivot points. Connect enough chain together to reach around both chainrings and cross them in the middle.
    Attached Thumbnails Attached Thumbnails Drawbridge for bikes.-bridge-2.png  


  9. #9
    I need a new name
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    Here's my very rough sketch. This isn't to scale and all that stuff. For simplicity it's drawn as one-way but the same rigging from the opposite direction should allow two-way traffic.
    Attached Thumbnails Attached Thumbnails Drawbridge for bikes.-drawbridge.jpg  

    i ride bikes

  10. #10
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    I like the simplicity of Hillybilly Hank's drawing. Just remember to add the appropriate counter weights. I don't see why it wouldn't work bi-directionally though.

  11. #11
    I need a new name
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    Quote Originally Posted by robbiexor View Post
    I like the simplicity of Hillybilly Hank's drawing. Just remember to add the appropriate counter weights. I don't see why it wouldn't work bi-directionally though.
    Counter weights or off center pivot works too. The teeter in my yard is off center but it's easy enough to screw some extra boards on to adjust weight as needed.
    i ride bikes

  12. #12
    Toro
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    It doesn't have to be exactly like a draw bridge. Just similar. With a pylon in the center of the crossing and no pulleys... A criss-cross overlap system could do the trick.

    Keep the designs coming. I'll design this in 3d when i get a chance. Thanks all.
    Ricardo aka "El Toro"
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  13. #13
    Unpredictable
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    It's not going to be easy getting the Queen Mary under those bridges

  14. #14
    Toro
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    I forgot to mention that canoes and kayaks must fit under the bridge.












    Just kidding.
    Ricardo aka "El Toro"
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  15. #15
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    Why would you want something like this on your trails?

  16. #16
    Toro
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    Reasons stated above. I want all sorts of crazy stuff I probably won't get approved. The cool thing is that if I don't get approval I will build it in my back yard.

    Short answer. Because it's different, ingenious, a good filter for advanced skills sections, etc. And, of course, this trail section would be a branch and not a main line.

    Shorter answer, because it's cool. And because I already got a no to build a hamster wheel.
    Ricardo aka "El Toro"
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  17. #17
    I build my own.
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    A quick image search found this at Whistler on "A River Runs Through It". This means it's been done and approved by a team of lawyers. That's good news for you.

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  18. #18
    featherweight clydesdale
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    Quote Originally Posted by Trail Ninja View Post
    A quick image search found this at Whistler on "A River Runs Through It". This means it's been done and approved by a team of lawyers. That's good news for you.
    Yeah, but if you have an IMBA Club/Chapter's insurance policy, which doesn't allow teter-totters because they have moving/articulating parts, I don't see how this will be insured either.
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  19. #19
    I build my own.
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    Quote Originally Posted by Fattirewilly View Post
    Yeah, but if you have an IMBA Club/Chapter's insurance policy, which doesn't allow teter-totters because they have moving/articulating parts, I don't see how this will be insured either.
    No, it wouldn't. It's definitely a teeter. The "Whistler did it" argument might help in other cases but if your insurance forbids it, you're out of luck. I'd never get that approved in any of the public parks I build in. I've never built a municipal skills park but I see things in some of those parks that my parks would never allow.
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  20. #20
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    when you say "drawbridge" are you simply talking about 2 teeters (that move through whatever angle) that articulate together, or do you mean something that actually opens wide enough to allow some one or something to pass through the space?

    Seems to me like a dual-teeter, the second half is really just there to make it intimidating, or ridable in both directions is a different design problem than something that's meant to open up enough for something to pass through.
    If you were really building a draw bridge, and the opening was for boats... that would be the coolest thing ever.

  21. #21
    Toro
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    This is purely academic. But thank you all for the supportive and negative feedback. The objections are all of great concern. I wouteeters that build anything I don't have approval for. I'm just an enthusiastic builder that cannot, unfortunately, devote time to tOur administrative side if things. Having said that, there is a skills trail in one of our parks. This was state approved. The new master plan has extended it. Therefore, the possibility for new features exists. Currently, two tweeters are there. As a result, the proposal of another set of tweeters that happen to create a bridge might not be such a difficult thing to get approved.

    I'd rather design it and have it rejected as a complete idea than have it shot down as a result of poor presentation.

    So, for our purposes here, this is an academic endeavor. Thank you all!

    Besides, nothing stops me from building in my backyard.
    Ricardo aka "El Toro"
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  22. #22
    Toro
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    Joules,

    I like how you think. I want one that well allow traffic underneath. Mutual actuation of two articulated ramps. Muahahaha!
    Ricardo aka "El Toro"
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  23. #23
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    How about this? Two teeter totters connected at the end with a pin/slot mechanism. As one goes down, it pulls the other with it.
    They would need to lock together when full down. I'll try to sketch that up when I get a chance later.

  24. #24
    Toro
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    I like it. It might not be exactly what I'm looking for but I like it.

    I was thinking of something similar but with extensions that interlock to pull the other down.
    Ricardo aka "El Toro"
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  25. #25
    Team Livemedium
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    this could work if accessed from one direction

    when I think drawbridge Im thinking castlestyle. one sided.

    good luck
    Keep trying to do the awesomest thing you've ever done.

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