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  1. #1
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    offset 135mm frame for non fat bike.

    Why not make an offset frame for regular mtbs that is only offset 10mm or so to get a nice symmetrical spoked wheel, and either run a 83mm BB, or a 73mm with a 10mm wider chainline?

    You could even give it tire clearance for up to 4" tires for use with IGHs, 1x, or other abbreviated gearing option, and a narrower q-factor for those with narrow hips. A unique chainstay design may be needed for crank and tire clearance though.

    It would make a nice versatile frame.

    I guess it just makes about as much sense as going to a regular 150 or 157mm hub though, except that the 135mm hubs are cheaper, more common, and in the case of IGH, all that's available.

  2. #2
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    I think the simple answer is non-fat bikes are doing great as is so nobody is motivated to try something non-standard. I can't recall the last time I rode MTBs with anyone who destroyed a rear wheel. That seemed to happen a lot more frequently 15yrs ago. I've also maxed out the fattness of tires in my non-fat frames and not run into any tire vs. chain issues. I run bigger tires than most so there isn't a whole lot of interest in going to fatter rubber in the mainstream.

    Offset frames in non-fat bikes seems like a solution in search of a problem to fix.
    Safe riding,

    Vik
    www.vikapproved.com

  3. #3
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    I recall that some manufacturer had started marketing a road bike frame like this a few years back. They advertised it as a "first" and a new concept. Then somebody on one this forum (or another of the Fatbike forums I spend too much time reading) pointed out that it was THE common practice for fatbike builds at the time. Seems kind of odd that it was a road bike that tried to "mainstream" the practice since a mt. bike would have greater need for a strong balanced wheel.

    Looking at my Ringle Lawill downhill 165mm hub, (and most 170 mm fatbike hubs) the flanges are nearly symmetrical (they moved the brake side flange further inward). This tells me the downhillers are indeed concerned about spoke symmetry and balanced tension.

    As to regular MTB's, I imagine it might be difficult to engineer an asymmetrical offset frame where the dynamic flex of the stays on both sides is as balanced as a symmetrical frame. Would both sides flex the same amount in the same way? or would the rear wheel move slightly out of alignment when cornering or hitting bumps? But Puglsey riders never seem to complain of squirrely rear end handling, so I imagine any dynamic alignment issues are insignificant.

    It sounds like a good idea for MTB's that would require a modest amount more engineering and cost, but with little significant benefit over the simpler and cheaper existing practice (of having spokes about 2-3mm shorter with slightly higher tension on the drive side). At least little benefit for most, until you start subjecting the rear wheel to LOTS of force.

    Lots of bike design issues persist long after there are better ways simply because of tradition and marketing too. Every time I am following someone on a Moonlander I keep thinking that if I did not know better, I would assume their frame must have been run over.

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