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  1. #1
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    Fat rim design, spoke triangulation, and wheel strength

    I was looking at the Marge Lite recently and noticed that it is designed to be laced offset or straight. The thing that mystifies me is the straight laced version requires your spokes to be offset from each other by a few centimeters or so. Isn't this counter to the concept that higher triangulation makes a stronger wheel?

    Wouldn't a third set of holes right in the middle make the most sense or heck get rid of the ones on one side and have a centered set and an offset set. Then the wheel build would be properly triangulated in both configurations and would be designed to take advantage of the inherent strength and rigidity of the wider hubs of fat bikes.

    Seems like a missed opportunity for a stronger wheel build for the non-offset crowd and on a rim like the marge lite that strength could be needed for non-snow riding.
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  2. #2
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    I couldn't agree with you more, and was actually thinking of starting this very thread. I've always been curious about the claims of those who say, "symmetrically laced wheels are stronger" when they're lacing up trapezoids. What's up with that?

  3. #3
    That Unicycle Guy
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    I am also curious about this, but think that the wide spoke spacing makes sense with these wide single walled rims.

    The sidewalls are the strongest part of the rim and it makes sense from a spoke tension standpoint to have the spoke heads near the sidewalls so they don't pull the centre of the rim too far inward.

    having said that a higher spoke angle should mean a laterally stiffer wheel.

    I have a GFS cross laced and I thought it would be the best of both worlds but it is one of the most unstable wheels I have ever built. When stress relieving you could see the rim twist.

    I want to re-build it with a regular lacing pattern but I don't have the right spokes.


    Has anyone had issues with lateral flex with almost-vertical spokes on these kind of rims?

  4. #4
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    Wide rims - nothing to stop you drilling a new set of holes.

    I've done all my fat wheels with a crossover lacing so the right flange goes to the lhs spoke holes. Makes for a very stiff wheel.
    As little bike as possible, as silent as possible.
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  5. #5
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    Quote Originally Posted by Velobike View Post
    Wide rims - nothing to stop you drilling a new set of holes.

    I've done all my fat wheels with a crossover lacing so the right flange goes to the lhs spoke holes. Makes for a very stiff wheel.
    I would be ok with drilling it just seems surly an all the manufacturers that don't offer just holes down the middle are missing the point behind building up wheels. If you have more triangulation you can have less tension which means that everything is less stressed. Ultimately that would lead to a longer lasting wheel and less failures due to less tension in the wheel at the spoke holes and less tension at the hubs.

    If i upgrade to the marge lites I will probably drill them to lace them straight anyways but it would be nice to not have to drill a new rim just to make it like it should have come.
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  6. #6
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    @rockcrusher, it sounds like you're building a symmetrically laced wheel, yes? Is it "conventional" gearing (ie cassette/derailler)? If you are, a typical (135mm) 9-speed, disc hub has the midpoint between the flanges "offset" from the midpoint between the dropouts approximately 14 mm (I'm not sure about 170mm hubs, if you're using one, but I would assume this still holds pretty accurate). Thus, you should be able to build a wheel with much less dish if you build to the non-drive side holes in the rim. If you're working on a Pug with a 9-spd hub, your lacing to the center of the rim would be optimal, IMO.

  7. #7
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    Quote Originally Posted by JR Z View Post
    @rockcrusher, it sounds like you're building a symmetrically laced wheel, yes? Is it "conventional" gearing (ie cassette/derailler)? If you are, a typical (135mm) 9-speed, disc hub has the midpoint between the flanges "offset" from the midpoint between the dropouts approximately 14 mm (I'm not sure about 170mm hubs, if you're using one, but I would assume this still holds pretty accurate). Thus, you should be able to build a wheel with much less dish if you build to the non-drive side holes in the rim. If you're working on a Pug with a 9-spd hub, your lacing to the center of the rim would be optimal, IMO.
    Actually I am future planning for an asymmetrical 135mm front hub for a Jones. I would like something less heavy than the current double walled rim I have now and something cooler looking as a bonus. The Marge Lite seems to fit this criteria but I am also weary of its strength in a non-snow bike format but in a rockcrawler rigid singlespeed AZ bike format.
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    Ah, gotcha. I e-mailed Surly a while back about the durability of their wheels and what would be acceptable to ride on them. I was told that, "the original Large Marges are the only 'fatbike' wheels they made rated for moderate drops" and generally rough terrain. I'm not saying, "single-walls won't hold up" as there's plenty of proof to the contrary on these forums. I am saying that I was told the single walls weren't meant for summer-type abuse. I'm sure you've already thought about all this, just putting it out there, though.

  9. #9
    That Unicycle Guy
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    Quote Originally Posted by JR Z View Post
    Ah, gotcha. I e-mailed Surly a while back about the durability of their wheels and what would be acceptable to ride on them. I was told that, "the original Large Marges are the only 'fatbike' wheels they made rated for moderate drops" and generally rough terrain. I'm not saying, "single-walls won't hold up" as there's plenty of proof to the contrary on these forums. I am saying that I was told the single walls weren't meant for summer-type abuse. I'm sure you've already thought about all this, just putting it out there, though.
    I think they are being over conservative with that answer. A LM can easily handle "moderate drops" and more. It is probably the most bomber bike rim ever built.


    It appears that the fat bike industry is taking some cues from trials bikes on rim design. makes sense since both want wide light strong rims. Trials rims used to be all double walled, now they are mostly single. started off with no holes, then round holes, and now square holes are common...

  10. #10
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    I've seen Large Marge wheels take 8-foot drops (to transition) and cheerfully survive impacts that have bent forks and snapped frames.

  11. #11
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    Quote Originally Posted by rockcrusher View Post
    I would be ok with drilling it just seems surly an all the manufacturers that don't offer just holes down the middle are missing the point behind building up wheels. If you have more triangulation you can have less tension which means that everything is less stressed. Ultimately that would lead to a longer lasting wheel and less failures due to less tension in the wheel at the spoke holes and less tension at the hubs.
    Less tension might not be such a good thing. It would work to resist the lateral loads but your wheel also needs to resist brake and drive forces, if you have less tension the wheel could flex in rotation. Repeated flex is not usually a good thing. In addition more triangulation can lead to more extreme bend at the spoke nipples and where the spoke comes over the hub flange, neither are totally desireable. Like everything alse the wheel is made up af tradeoffs. Enough triangulation to resist lateral loads but not so much as to lead to other problems.
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  12. #12
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    Good quality fat rims are hard to manufacture. When I originally designed the Uma 70mm rims, the spoke holes were down the center. I found that by moving them off center (both directions), it is easier to true them radially/laterally.
    Speedway Cycles owner http://fatbackbikes.com

  13. #13
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    Quote Originally Posted by Velobike View Post
    Wide rims - nothing to stop you drilling a new set of holes.

    I've done all my fat wheels with a crossover lacing so the right flange goes to the lhs spoke holes. Makes for a very stiff wheel.
    Yeah, I'm with you - but what rims are you using? I'm running undrilled double wall 100's.

    I did just build up a 28mm offset moonlander rear wheel - and cross lacing just had too much angle from drive flange across to the other side. I drilled another set of holes between the existing ones on one side. If I had read this first, I would have drilled them on the centerline - and crosslaced.

    I'm going to agree with the OP that 3 full lines of spoke holes would be a good "all purpose" rim layout - but the strength of the centerline set could be an issue with large cutouts on a singlewall rim. Something like this would be excellent:
    This isn't a "you're doing it wrong" topic.

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  14. #14
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    Quote Originally Posted by wadester View Post
    Yeah, I'm with you - but what rims are you using? I'm running undrilled double wall 100's.[/IMG]
    These DHL 80mm



    I've done a 100mm but I haven't used it yet (only just got a suitable frame)


    SX-RK3 hub with 100mm rim, 2 cross spoking and crossover - before final tension.
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  15. #15
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    Wow, this all great info! Some stuff I hadn't thought of, yet. Awesome.

  16. #16
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    Quote Originally Posted by rockcrusher View Post
    Seems like a missed opportunity for a stronger wheel build for the non-offset crowd and on a rim like the marge lite that strength could be needed for non-snow riding.
    You have to keep in mind that fat-specific products (not including Little Debbie) are still very low volume. Doing as you suggest (two different drilling options) means two sku's to order, keep track of in inventory, and reorder--for Surly as well as your LBS.

    I suppose it's possible that on-center drilling these rims could be beneficial in some measurable-by-enginerds way, but I think it's also as likely that it could be detrimental. In short, having built many flavors of single wall rims both on center and offset over the past decade, I don't currently see a good reason to alter them from their stock state.

    But if you do, let us know how it goes.

    Cheers,

    MC

  17. #17
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    Quote Originally Posted by mikesee View Post
    You have to keep in mind that fat-specific products (not including Little Debbie) are still very low volume. Doing as you suggest (two different drilling options) means two sku's to order, keep track of in inventory, and reorder--for Surly as well as your LBS.

    I suppose it's possible that on-center drilling these rims could be beneficial in some measurable-by-enginerds way, but I think it's also as likely that it could be detrimental. In short, having built many flavors of single wall rims both on center and offset over the past decade, I don't currently see a good reason to alter them from their stock state.

    But if you do, let us know how it goes.

    Cheers,

    MC
    Thanks! I appreciate a highly experienced builder input. I am leery of the Lites performance as a rockcrawler type wheel, only in so much as my experiences with singlewall rims is limited to cheap bikes and the unknown. I know surly doesn't recommend them to be used off snow environments but I think as Fat bikes evolve and become not just the domain of the snow and beach but start to venture out onto rocky trails and other environs people will be more demanding of the wheel. I would like to use this rim to offset the increased weight cost of using the Larry Fat front option on my bike, not that I would probably notice it directly but mentally the weight is there and sometimes that is enough.

    Of course i suspect a good wide 26" trials rim would be more than sturdy I suspect. Although it might not be any lighter than the Large Marge I have now.

    Anyway thanks for all your inputs all!
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  18. #18
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    Hi Velobike, I saw you had some postings on the DHL 80 rim. I just bought some Weinmann DHL 100mm rims and want to use them on my Pugsley. I was planning on re drilling offset to the right and lace them all to the drive side. Any thoughts on drilling new holes? I was just planning on offsetting the new hole set 20mm offcenter. I was also planning on using the Orgin8 26x4.0 tires that are out now. I've mounted BFL's on the Pug and only saw minor drivetrain interference. I'll be running a 1x9 drivetrain. Thanks for any input you may have.
    -Shawn

  19. #19
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    Quote Originally Posted by Velobike View Post
    Wide rims - nothing to stop you drilling a new set of holes.

    I've done all my fat wheels with a crossover lacing so the right flange goes to the lhs spoke holes. Makes for a very stiff wheel.
    Hey VB--do you have any means for quantifying the stiffness you say comes with cross lacing?

    I ask because I have an idea.

    This idea came as a result of experimenting with cross lacing years ago, and then again recently. And my experience is that it's just the opposite of stiff: Aside from the whacked angles the spokes take from hub to rim, and forgetting about the odd angle the nips sit at, what I found was that a cross laced wheel was substantially *less* stiff, less stable than a "normal" (non-cross-laced) wheel. The only reason it works (I think) on fat rims is when you use doublewalled rims--they are so freaking burly to begin with that you could skip half the spokes and most of the tenison and still end up with a rideable wheel.

    I'll share my idea, if appropriate, after you've had a chance to answer. I think you'll like it.

    Cheers,

    MC

  20. #20
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    Quote Originally Posted by namaste1978 View Post
    Hi Velobike, I saw you had some postings on the DHL 80 rim. I just bought some Weinmann DHL 100mm rims and want to use them on my Pugsley. I was planning on re drilling offset to the right and lace them all to the drive side. Any thoughts on drilling new holes? I was just planning on offsetting the new hole set 20mm offcenter. I was also planning on using the Orgin8 26x4.0 tires that are out now. I've mounted BFL's on the Pug and only saw minor drivetrain interference. I'll be running a 1x9 drivetrain. Thanks for any input you may have.
    -Shawn
    99.9% certain that the extrusion on that rim is thick in the plane the spoke holes are drilled in, and thin elsewhere. In other words, they can be redrilled, but you gotta stay in line with the existing holes or you'll (likely, soon) see cracks around the spoke holes and (eventually) they'll pull through.

    MC

  21. #21
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    Quote Originally Posted by namaste1978 View Post
    Weinmann DHL 100mm rims. I was planning on re drilling offset to the right and lace them all to the drive side. Any thoughts on drilling new holes? I was just planning on offsetting the new hole set 20mm offcenter. Thanks for any input you may have.
    -Shawn
    These rims have 2 ribs that tie the inner&outer together - so as long as you miss those ribs, you're golden. Should be able to locate them with a probe thru the existing holes.

    The existing spoke holes are +/- 25mm from centerline, so drilling a new set 5mm closer to center shouldn't hit the rib - but still worth checking because you need the diameter of the inner access hole to clear too.

    I recently built up a moonlander rear wheel - but I just drilled the new holes in line with the existing on that side.

    Also, 3/16" plastic furniture hole plugs fill empty spoke holes snugly.
    Attached Thumbnails Attached Thumbnails Fat rim design, spoke triangulation, and wheel strength-img_1830s.jpg  

    This isn't a "you're doing it wrong" topic.

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  22. #22
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    That's exactly what I wanted to do but these rims came with spoke holes just like that but on these rims they are much closer to the center. If I drilled another hole inline with one set, they would be less than 10mm offcenter. For some reason these rims have a much tighter lacing pattern. They are not as widely spaced as yours appear to be. I tried to upload a pic but i don't have enough posts yet...lol...jeez If you go to SeattleFatbike, you can see the pic that I just posted there.

  23. #23
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    Sorry, the pic is on SeattleFatbike on Facebook. I have a page there.

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    Ok, got 10 posts down, now I can post the pic
    Attached Thumbnails Attached Thumbnails Fat rim design, spoke triangulation, and wheel strength-imag0940.jpg  

    Last edited by namaste1978; 02-18-2012 at 05:02 PM.

  25. #25
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    Quote Originally Posted by namaste1978 View Post
    ...I was planning on re drilling offset to the right and lace them all to the drive side. Any thoughts on drilling new holes?...
    ...I'll be running a 1x9 drivetrain...
    I haven't tried drilling my 100s, but as Mike says watch out for the internal ribs, and also the existing holes will be on the thickest alloy, so it's probably an idea to stay close to that line. If you are going to venture onto the thinner sections but it would be wise to use a nipple washer to spread the load - probably not a good idea though.

    I can't comment on a derailleur drive train as I only run SS or hubgears, so no experience with them on a fatbike.
    As little bike as possible, as silent as possible.
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