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  1. #1
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    Reputation: roxo56's Avatar
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    FS FATTY frame design in acad 2014

    I'm posting these screen caps over here at the suggestion of some over on the fatbike section who say this is a better place to seek some geometry advice and frame tweaking. I'm about 95% concrete on things such as pivot type and pivot location, shock location and travel, etc... But what I need is advice on things like Headtube size, CS dropout selection or type, brake mounts/type , cable routing. Details, but more importanter to me now.

    Here's my general specs:

    Bud/Lou tires on 82mm rims (clownshoes do fit, though)
    3" major travel (9.5 deg) at rear axle, bump stop limited on seat tube.
    1.3" shock travel via link/pivot
    1x10 only and ever. Never to be anything but...
    MWOD crank at first with FSA 29 tooth ring via spider.
    Would be FS forks when available, hopefully soon.
    That probably requires tapered headtube ???
    Hydraulic braking front and rear. Bigger rotor in rear (need help with mtd. that).

    Anyways, take a look at let me know if you will...
    Thanks in advance. BTW, if you down load the pics from the links...they are huge !











    roxo56
    Surly Troll 650b

  2. #2
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    You probably need to raise or lower the drive side chainstay so it clears the chain. If it doesn't have a pivot at the dropout, I'd be inclined to make the stays symmetric. Speaking of which, with no pivot at the DO, the swing link design you have increases the movement of the stays in relation to each other vs a "normal" rocker (eg Trek Fuel) or upside down swing link (eg Fisher Sugar from BITD). FWIW...

    "bump stop limited on seat tube." If I'm reading this correctly--that the suspension actually bottoms out--it sounds sketchy as hell.

    Also, just a general note that doesn't really matter probably. For bikes with a swing li I, shorter travel ones generally atta he the shock to the TT whereas longer travel ones attach the who I to the DT. Just the way the geo works out see transition bandit vs covert or Santa Cruz Blur vs Nomad (which I realize is VPP. It the same principle applies)

  3. #3
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    I can't say anything about the design or geometry, but as a fellow CAD nerd...nice job!
    Jason
    Disclaimer: www.paramountsports.net

  4. #4
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    Are you actually going to build this, or is this just a CAD exercise? I see a lot of stuff that looks great in CAD and will be horrible/difficult to do for a first-timer. Just build a hardtail fattie first, eh?

    -Walt
    Waltworks Custom Bicycles
    Park City, UT USA
    www.waltworks.com
    waltworks.blogspot.com

  5. #5
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    I plan to have this built if I find a willing framebuilder, and get some of these other issues worked out first. Care to discuss the project ? PM me, if so, please...

    Already done a 3d "fly-around" chain clearance -heel strike study against the drive side CS position. Seems to clear nicely now, but it took a few redraws to get it right.
    Have eliminated all "compound" tube bends from CS and SS's, single plane bends only.

    Lot's of HT fatties already out there, not too interested.
    Don't need the CAD exercise,...I think...unless you're saying I do ?

    Quote Originally Posted by Walt View Post
    Are you actually going to build this, or is this just a CAD exercise? I see a lot of stuff that looks great in CAD and will be horrible/difficult to do for a first-timer. Just build a hardtail fattie first, eh?

    -Walt
    p.s.- Walt, very nice fabrication on display on your website, I salute your workmanship !
    roxo56
    Surly Troll 650b

  6. #6
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    I have a standing policy of never building anything for anyone who approaches me first with CAD stuff. I've learned over the years that it doesn't usually go well.

    IMO your best bet is Knolly if they are still doing this kind of project (I think they used to). Expect to pay prototyping rates - ie $10,000+ for the first frame.

    -Walt
    Waltworks Custom Bicycles
    Park City, UT USA
    www.waltworks.com
    waltworks.blogspot.com

  7. #7
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    Wow, horrible autocorrect errors from my phone in the last post.

  8. #8
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    Quote Originally Posted by Walt View Post
    IMO your best bet is Knolly if they are still doing this kind of project (I think they used to). Expect to pay prototyping rates - ie $10,000+ for the first frame.
    -Walt
    I am building a frame for myself that is a little out of my comfort zone. I was thinking that it was a lot more expensive in parts alone than the usual because I am buying things and then realizing I don't want to use them. So if I could somehow charge myself my consulting rates, $10K is actually about right.

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