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  1. #1
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    V-rack seatpost mod?

    So, as I was fiddling with removing the collar/shim/v-rack setup last night in preparation for a trip, I started thinking about why it had to be so hard? Sure, the whole arrangment of securing the v-racks into the frame isn't complicated, but couldn't it be easier?

    I wanted to get some outside input before I did this, but I see no reason why it can't work and be simpler and more elegant at the same time.

    Why not drill and slot the dummy frame where the v-racks insert (post holes?) and then just use a collar to secure it, exactly like a seatpost setup?

    My only assumption is that it's not done this way so that IF you were to run it without collars you might be able to damage the post hole by giving it a place to crack, but as long as you run collars all the time (like most do once they get them, I assume) it shouldn't be an issue?

    Any holes (no pun intended) in my theory? Then I could use a simple 1 bolt clamp, no shims, no stepped 2 bolt clamp. Lighter, easier to install and remove the v-racks, seems like a wiener to me..

    Plum
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  2. #2
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    The only concern I would have is that both the v-racks tubing and the tubing that they insert into is relatively thin metal...much thinner than a seat post (and smaller diameter), and thinner than the seat tube. I'd worry that you'd end up kinking the v-racks and/or the tubing they insert into.

  3. #3
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    Quote Originally Posted by lawfarm View Post
    The only concern I would have is that both the v-racks tubing and the tubing that they insert into is relatively thin metal...much thinner than a seat post (and smaller diameter), and thinner than the seat tube. I'd worry that you'd end up kinking the v-racks and/or the tubing they insert into.

    I did think of that, particularly with the v-rack tubing. I'm already clamping it (with my ghetto whatchamacollars) and I haven't seen any denting or crimping yet, and i'd assume that with the dummy frame being used to clamp them (via external collar) that the forces would be that much more distributed, but who knows?

    The dummy frame uprights are pretty beefy, I've seen reference to 1mm thick in areas, is that really thinner tubing thickness than a typical seat tube? Combined with the slide over collar, will it matter?

    All these questions and no real way to know until I start cutting.

    I do appreciate the help in asking the right questions..

    Plum
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  4. #4
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    I think the diameter difference between the dummy's frame internal diameter and the v-racks external diameter is much more significant than the difference between any seat post to seat tube diameter difference. You may see the frame form a sort of cone shaping on the BD frame if you cut and clamp as you described.

  5. #5
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    Quote Originally Posted by PScal View Post
    I think the diameter difference between the dummy's frame internal diameter and the v-racks external diameter is much more significant than the difference between any seat post to seat tube diameter difference. You may see the frame form a sort of cone shaping on the BD frame if you cut and clamp as you described.
    I'm actually starting to see a little 'pinch' develop in the upright from the collar on there now.

    I guess it might cone if I slice it, but it appears to be starting to cone already, so which would be worse, coning without a slice or deforming without any way to relieve it? Don't know.

    Plum
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  6. #6
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    I wish they had installed some spring pins like they did with the wideloaders. If you are considering drilling, you could install them yourself.

    http://www.xtracycle.com/cargo-bicyc...pring-pin.html

  7. #7
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    Quote Originally Posted by PScal View Post
    I wish they had installed some spring pins like they did with the wideloaders. If you are considering drilling, you could install them yourself.

    http://www.xtracycle.com/cargo-bicyc...pring-pin.html
    Yep, another option.

    My preference would be to see each upright slotted with a pinch bolt, so you just drop everything in, tighten it up and you're done. No extra collars to mess with/purchase, etc.

    I'm probably going to do this method next time I'm due for a repaint (or when I get bored and decide to overhaul it. I'll have a builder slot the uprights and braze on a single pinch bolt. Then I can lose the collars. Would look very clean and tidy, IMO.

    Plum
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  8. #8
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    As spotted on a SUN cargo bike outside the shop in Charlevoix Michigan (revolution cycles?).

    Pretty close to what I'm envisioning, except for the bulky QR's. A nice, neat 5 or 6mm binder bolt would be nicer, IMO.

    Plum
    Attached Thumbnails Attached Thumbnails V-rack seatpost mod?-img00431-20110806-0956.jpg  

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  9. #9
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    Quote Originally Posted by Plum View Post
    Pretty close to what I'm envisioning, except for the bulky QR's. A nice, neat 5 or 6mm binder bolt would be nicer, IMO.
    Binder bolt would be neater, but the quick releases would be a lot quicker to use than a binder bolt. That may or may not be a good thing.

  10. #10
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    Quote Originally Posted by sfuller View Post
    Binder bolt would be neater, but the quick releases would be a lot quicker to use than a binder bolt. That may or may not be a good thing.
    Agreed, I don't need it to be too convenient for someone to make off with my v-rack setup, I just want it to look nicer and less like an afterthought.

    Plum
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