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Thread: CS / BB Yoke

  1. #1
    Mr.650b - Mr.27-5
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    CS / BB Yoke

    I was browsing through some of my old sketch books last night and stumbled upon this. It’s a concept I had while working at Litespeed / Merlin for an investment cast, titanium bb-yoke assembly. The idea was that you could gain a lot of chainring and tire clearance and simplify the manufacturing (bending, dimpling, mitering, etc) of the chainstay. The two small bosses you see on the drive side of the yoke were intended for mounting a chain-suck device to.

    Not sure there would be any real call for this today, though it would certainly be a helpful component for Fat Bike frames. I guess it could be made in steel and titanium. But I don’t know that there would be enough demand to justify tooling costs. If you feel differently please let me know, maybe we’ll pursue it. Hard to believe I sketched this 12 years ago… how time flies! Like it here.

    Cheers,
    KP

    CS / BB Yoke-bb-yoke.jpg
    “Those that say it can’t be done should get out of the way of those doing it.”

    Pacenti Cycle Design

  2. #2
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    Few things to consider regarding fat bikes: 1 they use 100 mm BB and 2 tires sizes and chain rings complicate all kinds of things. They are a different animal and are still being developed.
    Paragon makes ti 100 mm BBs.

  3. #3
    Mr.650b - Mr.27-5
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    Quote Originally Posted by Testmule View Post
    Few things to consider regarding fat bikes: 1 they use 100 mm BB and 2 tires sizes and chain rings complicate all kinds of things. They are a different animal and are still being developed.
    Paragon makes ti 100 mm BBs.
    Yep, well aware of the differences between MTBs and FBs. I didn't mean to imply that the same casting could be used for both standard MTB frames and Fat Bikes; but rather, that the concept would work equally well for either when designed for the intended use.

    Again, this sketch was done 12 years ago. Lot's of things are different now, even for regular MTB frames.

    Cheers,
    KP
    “Those that say it can’t be done should get out of the way of those doing it.”

    Pacenti Cycle Design

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    Definitely interested in yolk options. I'm doing steel tig welded 29r+ knard bikes with 73mm BB and 4+" snow/fat with 100mm BBs. The knard bike needed the most finessing with bending and dimpling. I would buy yolks for both. The paragon yolk is not what I need for the 29r+.
    thanks
    andy walker

  5. #5
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    Paragon already makes this, basically. And to be honest fitting fatbike tires in isn't very hard with existing chainstays so I'm not sure you'd sell many. Getting that d*** chain to stay away from the tire is the challenge!

    The ti guys might feel differently but it's not something I'd use.

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

  6. #6
    Mr.650b - Mr.27-5
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    Quote Originally Posted by Walt View Post
    Paragon already makes this, basically. And to be honest fitting fatbike tires in isn't very hard with existing chainstays so I'm not sure you'd sell many. Getting that d*** chain to stay away from the tire is the challenge!

    The ti guys might feel differently but it's not something I'd use.

    -Walt
    Yep, saw the PMW one a couple (?) years ago; really nice part. Though a one-piece cast version could certainly be made much lighter and probably for 1/3rd the cost. But that wasn't really the point. Mostly thinking out loud... and sharing a sketch I did over a decade ago. We had yokes back then too, not much new under the sun.
    “Those that say it can’t be done should get out of the way of those doing it.”

    Pacenti Cycle Design

  7. #7
    Mr.650b - Mr.27-5
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    I just realized that the OP might not have made clear the real goal of the design, which was to cast the BB and yoke as one piece. As I said above, there were / are plenty of yokes around. But casting them along with the bb shell would have been a first, afaik.
    “Those that say it can’t be done should get out of the way of those doing it.”

    Pacenti Cycle Design

  8. #8
    Who turned out the lights
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    Could you make something cast like yours, but without the BB shell? Having it integral to the shell would dictate your CS length. I've considered the Paragon piece for a planned 29+ project, but there are two things holding me off: price, and the two-piece design. I don't tig, and I'm not 100% about brazing it and having it hold up with the way it's laid out.

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    I'm finding one needs a lot of benders, dimplers and ways to measure the clearance of tires, chainrings and cranks for big tired bikes. A better price than the pmw yoke would be nice. The pmw yoke, while very nice, is rather pricey and a put-off to non- tig folks. With a one piece yoke/bb, one could still adjust the CS's cutting the length to fit at the dropout end. Either with or without the bb shell, I think there is a market for your yoke.
    cheers
    andy walker

  10. #10
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    Kirk

    Nice piece, simple to use. Definitely workable.

    Eric
    If I don't make an attempt, how will I know if it will work?

  11. #11
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    Hey Kirk -

    I have a project for you. Investment cast me/us some post mount disc tabs like the Salsa ones here (not the best image but you can see what's basically going on):
    Fargo V2 Fork | Parts & Accessories | Salsa Cycles

    We are all hacking together stuff out of small pieces of tubing and flattened steel balls or pulley bosses or whatever and it sucks. A tab with a nice long extension ala the Willits ISO tabs from Paragon, with some extra tab height for mounting to different things - that would sell like hotcakes. I'll buy 100 or 200 or 500 if needed to get it going!

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

  12. #12
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    Yeah, that is true. When I raced for Schwinn in the 90s all the Homegrowns used a chainstay yoke type thing. Of course that was a mass-produced aluminum bike, but still. I wonder if you could find some old turn of the century bike with a yoke there (if they had not all been melted down for scrap drives).

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

  13. #13
    Mr.650b - Mr.27-5
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    Quote Originally Posted by Walt View Post
    Hey Kirk -

    I have a project for you. Investment cast me/us some post mount disc tabs like the Salsa ones here (not the best image but you can see what's basically going on):
    Fargo V2 Fork | Parts & Accessories | Salsa Cycles

    We are all hacking together stuff out of small pieces of tubing and flattened steel balls or pulley bosses or whatever and it sucks. A tab with a nice long extension ala the Willits ISO tabs from Paragon, with some extra tab height for mounting to different things - that would sell like hotcakes. I'll buy 100 or 200 or 500 if needed to get it going!

    -Walt
    Something like this? I started working on this in June, 2012... but never pulled the trigger. I was afraid that with the mass adoption of 15mm TA wheels, a 9mm QR fork wouldn't sell very well.
    Attached Thumbnails Attached Thumbnails CS / BB Yoke-pacenti-fork-assembly.jpg  

    “Those that say it can’t be done should get out of the way of those doing it.”

    Pacenti Cycle Design

  14. #14
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    I was thinking of a separate unit, rather than a dropout-integrated setup. People are using all kinds of diameter/bend/taper when it comes to fork blades, so what you've got there is super cool but would only work for some forks.

    And yes, it would only work for QR that way. Better to have a separate/universal tab to allow different dropout options, IMO. Casting is probably the way to go since you avoid dealing with machining on multiple axes. But I could be wrong.

    Paragon makes one but it's way expensive and the tab is IMO not long enough for a fork:
    www.paragonmachineworks.com - BK2017SteelPostStyleCaliperMountUniversal

    Also remember that there are a ton of us building road/cross/gravel bike forks with QR and disc tabs. There's plenty of market for rigid forks with QR still.

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

  15. #15
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    CS / BB Yoke

    A cheaper than Paragon cast yoke for 73 shells (29+ frames ) would be very nice. I'd buy some. Not a part of a BB shell though.
    The dimpling for ring and tire clearance is IMO too much, using even regular oval chainstays like the Dedacaai's. So much so that I bet many will start using 83mm shells on 29+ bikes soon (unless they make their own yokes).
    I hate the use of 100mm shells on 29+ bikes, overkill and the crankarm Q is silly.
    For Fatbikes I don't know if I'd buy one since I think there is more real estate unless you're making a short chainstay fatty that'll fit 4.7's. But if it were light and cheap enough I think it'd sell (yoke and 4130 tubing cost less than nice pre-bent chainstays... <$40?).
    Check out Rick Hunter's yoke, it's not cast but it's a design that's pretty awesome.

  16. #16
    Mr.650b - Mr.27-5
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    Quote Originally Posted by Walt View Post
    I was thinking of a separate unit, rather than a dropout-integrated setup. People are using all kinds of diameter/bend/taper when it comes to fork blades, so what you've got there is super cool but would only work for some forks.

    And yes, it would only work for QR that way. Better to have a separate/universal tab to allow different dropout options, IMO. Casting is probably the way to go since you avoid dealing with machining on multiple axes. But I could be wrong.

    Paragon makes one but it's way expensive and the tab is IMO not long enough for a fork:
    www.paragonmachineworks.com - BK2017SteelPostStyleCaliperMountUniversal

    Also remember that there are a ton of us building road/cross/gravel bike forks with QR and disc tabs. There's plenty of market for rigid forks with QR still.

    -Walt

    Yeah, casting is the way to go. I will play around with a separate unit. I agree, would be much more versatile.

    Cheers,
    KP
    “Those that say it can’t be done should get out of the way of those doing it.”

    Pacenti Cycle Design

  17. #17
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    That sounds awesome, Kirk. Seriously, you'd sell a ton. I would use at least a hundred a year, I'd guess. Many other builders who do forks (or frames that use non-integrated disc tabs/dropouts) would use a ton too.

    I think the yoke minus the BB might be worth doing too, actually.

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

  18. #18
    Harrumph
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    I used the Paragon Yoke in a 29+ project, and it is really cool. I honestly felt bad going at it given my skill level and how much lighter my pocket book ended up, but it's no doubt a gorgeous hunk of metal.

    The Fatbike trend is of course "Huuurnag aaaaaa bigger is awesomer!!!," but I think that will settle down eventually. While brainstorming a potential build for a friend the subject of a 26x3.8/29x3 compatible frame using an 73mm bb. This had me looking at the bike I had built with the Paragon yoke wondering if there was a clean way to make it juuuust a little bit wider to clear the 3.8 and allow a full 3x10 in 29x3 mode.

    So while we're spitballing with KP in the room, here's my request: Make some yoke halves, a socket for the bridge and a socket for the chainstays. You could use just one half on the drive side if the build called for it, or both sides and you choose how wide the bridge is.

    Another thing that popped into my head once starting this reply would be to cast the bb-yoke in halves. Kind of like your original drawing KP, but cut in half longitudinally. One half would have a yoke part and enough BB for threads and a means of using straight gauge tubing to join it to the other half. The builder could then set how wide the bb is with the sleeve.
    Slowly slipping to retrogrouchyness

  19. #19
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    CS / BB Yoke

    Quote Originally Posted by G-reg View Post

    So while we're spitballing with KP in the room, here's my request: Make some yoke halves, a socket for the bridge and a socket for the chainstays. You could use just one half on the drive side if the build called for it, or both sides and you choose how wide the bridge is.

    Another thing that popped into my head once starting this reply would be to cast the bb-yoke in halves. Kind of like your original drawing KP, but cut in half longitudinally. One half would have a yoke part and enough BB for threads and a means of using straight gauge tubing to join it to the other half. The builder could then set how wide the bb is with the sleeve.
    I like this idea a lot.
    Speaking as someone who knows nothing of the difficulty in making such a modular thing.

    Being able to micro adjust (widen or decrease) the amount of tire and ring clearance would be killer!
    The sockets relieved for 0.035 tubing.

    The front post mount disc tab is an awesome idea too.

  20. #20
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    Hey,
    +1 to what Walt said, I'm almost done designing a laser cut with brazed insert post mount fork option. Making that stuff is fun and unique and all but if I could buy one that would be really cool. I wold love to see what you come up with.

  21. #21
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    I think the problem is that once you split the yoke in half, you might as well just use a piece of plate, which is pretty easy to do on just the driveside. I'm having a hard time envisioning this half-a-yoke...

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

  22. #22
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    Quote Originally Posted by Meriwether View Post
    So much so that I bet many will start using 83mm shells on 29+ bikes soon (unless they make their own yokes).
    I've got one just waiting for a 29+ frame, but the selection of 83mm BBs seems pretty limited unless I'm missing the magic search keyword.

  23. #23
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    Quote Originally Posted by Walt View Post
    I think the problem is that once you split the yoke in half, you might as well just use a piece of plate, which is pretty easy to do on just the driveside. I'm having a hard time envisioning this half-a-yoke...

    -W
    You're talking sense, which is why the thought likely died on the vine.
    Slowly slipping to retrogrouchyness

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    Loving the yoke idea and I think it would be popular for sure as it would cut down massively the amount of work needed in manufacturing. Personally I think on investment cost version of the Paragon design would be better as you would then be able to adjust the chain stay length better. Then again is demand is high enough you could also make different length versions with the bottom bracket built in. How much heavier would a setup be like this as compared to a tube and separate yoke (e.g. traditional way)?

  25. #25
    Mr.650b - Mr.27-5
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    Quote Originally Posted by Walt View Post
    I think the problem is that once you split the yoke in half, you might as well just use a piece of plate, which is pretty easy to do on just the driveside. I'm having a hard time envisioning this half-a-yoke...

    -W

    A "half yoke" would look something like this I imagine (Santa Cruz Highball / Chameleon). If you made the socket for the CS bridge straight rather than curved, one could adjust the width of the bridge to accomodate wider BB shells and tires. You could also then choose to use one or two yokes. Dozens of ways to skin this cat.
    Attached Thumbnails Attached Thumbnails CS / BB Yoke-santa-cruz-highball-alloy-29er-chainstay-yoke02.jpg  

    “Those that say it can’t be done should get out of the way of those doing it.”

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