# CS / BB Yoke



## Kirk Pacenti (Sep 26, 2006)

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&#8230; how time flies! Like it here.

Cheers,
KP


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## Testmule (Jul 27, 2013)

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.


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## Kirk Pacenti (Sep 26, 2006)

Testmule said:


> 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


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## afwalker (Apr 26, 2012)

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


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## Walt (Jan 23, 2004)

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


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## Kirk Pacenti (Sep 26, 2006)

Walt said:


> 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.


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## Kirk Pacenti (Sep 26, 2006)

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.


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## Francis Buxton (Apr 2, 2004)

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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## afwalker (Apr 26, 2012)

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


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## Eric Malcolm (Dec 18, 2011)

Kirk

Nice piece, simple to use. Definitely workable.

Eric


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## Walt (Jan 23, 2004)

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


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## Walt (Jan 23, 2004)

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


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## Kirk Pacenti (Sep 26, 2006)

Walt said:


> 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
> ...


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.


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## Walt (Jan 23, 2004)

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


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## Meriwether (Jul 26, 2007)

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.


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## Kirk Pacenti (Sep 26, 2006)

Walt said:


> 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.
> 
> ...


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

Cheers, 
KP


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## Walt (Jan 23, 2004)

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


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## G-reg (Jan 12, 2004)

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.


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## Meriwether (Jul 26, 2007)

G-reg said:


> 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.


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## adarn (Aug 11, 2009)

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.


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## Walt (Jan 23, 2004)

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


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## dr.welby (Jan 6, 2004)

Meriwether said:


> 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.


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## G-reg (Jan 12, 2004)

Walt said:


> 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.


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## woody74 (Apr 6, 2004)

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)?


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## Kirk Pacenti (Sep 26, 2006)

Walt said:


> 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.


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## afwalker (Apr 26, 2012)

Please help my poor attempts at yokes,




















bystickle hommage and my own attempt.
cheers
andy walker


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## Meriwether (Jul 26, 2007)

dr.welby said:


> 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.


You're right, as far as i know. I think it's limited to DH or Enduro crank sets like Shimano Saint? 
And you *should* use a 150 rear hub which limits it even more. But I bet with a 1x you could work with the chainline enough to use 135. Talking somewhat out my arse here.


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## Meriwether (Jul 26, 2007)

Kirk Pacenti said:


> 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.


+1. This would simplify it so much by not having to make multiple width yokes for all the new tire sizes.


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## dr.welby (Jan 6, 2004)

Meriwether said:


> You're right, as far as i know. I think it's limited to DH or Enduro crank sets like Shimano Saint?
> And you *should* use a 150 rear hub which limits it even more. But I bet with a 1x you could work with the chainline enough to use 135. Talking somewhat out my arse here.


I was thinking maybe a dishless 135 offset rear end. Or maybe one of those modded 6 speed cassettes? In the front I'd just run the two inside chainrings of a triple, assuming such a crank existed. Maybe Phil Wood could be talked into making some 83mm square-tapered spindles?

Back on topic, I've also thought about half-yokes, and in my mind they included a bridge to further simplify construction. I've also though that the end that connect to the chainstay could have a 1 1/2" hood like a Wright dropout - then you could miter it like it was going to fit against a bottom bracket.


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## Kirk Pacenti (Sep 26, 2006)

All good ideas, i will knock the yoke concept around some more... but I am going to pursue the post mount casting first. 

Cheers, 
KP


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## shirk (Mar 24, 2004)

How about some updated lugs for modern mtb geo?


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## Kirk Pacenti (Sep 26, 2006)

shirk said:


> How about some updated lugs for modern mtb geo?


I could poll my customers, but I doubt the demand would justify the expense.


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## Thylacine (Feb 29, 2004)

Casting is totally underrated. I still maintain that you could make a steel XC full-suspension frame using cast junctures that would be the same weight as Aluminium.

What's the deal with welding together/onto the current generation of castings though? Or are we taking brazing only?


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## seren (Dec 6, 2013)

I could only take a dozen or so, but I would love some nice lugs for modern mtb geo. 

Kirk, what's the minimum to make it economical, 100's, 1000's?


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## Kirk Pacenti (Sep 26, 2006)

seren said:


> I could only take a dozen or so, but I would love some nice lugs for modern mtb geo.
> 
> Kirk, what's the minimum to make it economical, 100's, 1000's?


*Assuming* we could get away with just 3 main lugs and 1 BB shell (Not likely given the wildly varying geo needs of MTBs) one would have to sell a few hundred sets to just to break even. Not a very attractive proposition, imo.

Tooling and minimum production run would cost in the neighborhood of $18K. Lead time for a project like this is about 5-6 months. Not to say this would be impossible, but I can make a much better return on that money with other products.

Cheers, 
KP


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## Kirk Pacenti (Sep 26, 2006)

Thylacine said:


> Casting is totally underrated. I still maintain that you could make a steel XC full-suspension frame using cast junctures that would be the same weight as Aluminium.
> 
> What's the deal with welding together/onto the current generation of castings though? Or are we taking brazing only?


I agree, casting is an amazing technology that is completely underrated. I really want to get into Ti castings...

I do think you could make a lugged FS frame with steel. I think the problem is (assuming you match the weight of Al) would be stiffness. Mfg and material costs would also be significantly higher. As big a fan as I am of steel bicycles, I think they really are limited to hartail MTB and road/touring bikes.*** yeah, I know there are always exceptions to this. But I am speaking in general terms, for volume production.***

Welding to castings isn't a problem. It's not as clean / smooth as machined steel, but can be done with relative ease and reliability.

Cheers, 
KP


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## dr.welby (Jan 6, 2004)

Meriwether said:


> I think it's limited to DH or Enduro crank sets like Shimano Saint?


Profile makes a 6 7/8" spindle which seems like it could work, and a there's BMX chainrings that look like they could be drilled for a granny ring, which could make for an interesting indestructible backwoods setup...

And then there's machining your own spindles, something I don't think I'm up to yet. Or chopping and extending a spindle with a welded center sleeve?

stop the presses, hit the brakes, edit follows: Looks like Race Face has a bunch of 83mm cranks arms, plus there's some SRAM ones too.


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## Triton Bikes (Jan 6, 2010)

Hi Kirk!

When I read this thread I was like "YES! That's what we need!"

Paragon is now selling the Ti version for 29+ bikes.
Which is cool. But I asked them about any plans to produce the same yokes for normal 29ers. And Mark said no.

You know this for sure, due to the properties of titanium, it is more complicated to provide enough clearance for the setups with: 29x2.4 tire + 2x10 transmission + short stays.

Something that is easily achievable with steel, alu or carbon fiber 29ers, cannot be done out of 22mm (7/8") chainstays. In case you want a stiff frame.

So we have to spend a lot of time and effort building quite heavy boxed yokes / or half yokes (yet to come here at Triton).

Customers are willing to have enough clearance AND a stiff frame! They are willing to pay for that.
I am sure if it's a nice and a working piece of Ti, I will be buying them. And I will use one for my own future 29er

Below is what we have to do to allow more clearance.

Please make it happen!

Thanks!

Dmitry

Triton Bikes

Moscow, Russia


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## 18bikes (Jan 15, 2007)

I've been working on a yoke/plate for a while now, there are a couple of pics here: Untitled | Flickr - Photo Sharing!. (I've lost my post 3 times trying to add the pics here so you'll just have to follow the link)

I was aiming for:

- good clearance (obviously)
- easy to make
- ISCG mount
- Mate with an oval chainstay
- 'self-fixturing' bridge with only one mitre

If I was going to cast them, I'd make a few changes:

- A small web to the back of the bb shell to make easier to position
- Move the hole for the bridge further away from the bb shell (I went close so I could do the bends without distorting the hole)
- A single curve instead of two bends, like the santa cruz one shown above.
- A socket/plug for the chainstay
- A zip tie cable guide along the top edge

If you could do all that I'd certainly take a few. If you did an ISCG and non ISCG version you could use it for lots of different widths by using a longer tube for the bridge. You'd also have the option of having doing a non-ISCG frame by using two non-drive side ones.

Even if you only did one without ISCG to use on both sides, I'd still be interested, although I'd only use one on the drive side

Matt


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## Triton Bikes (Jan 6, 2010)

Inspired by the 3″ yoke made by our friends at Paragon we designed from scratch our yokes to provide clearance to 2.5″ tires, and yet provide enough clearance to drivetrain.
We have done stress and stiffness tests and the results are outstanding.
The yokes are less then 200 grams when installed on a Triton Ti frame.
Machined from thick Ti 6-4 billets.
First frames with Triton CNC yokes coming soon.

29er with 2.3" tire, 440mm chainstays and plenty of clerance for 2x10 drive


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## life behind bars (May 24, 2014)

Triton Bikes said:


> Inspired by the 3″ yoke made by our friends at Paragon we designed from scratch our yokes to provide clearance to 2.5″ tires, and yet provide enough clearance to drivetrain. We have done stress and stiffness tests and the results are outstanding. The yokes are less then 200 grams when installed on a Triton Ti frame. Machined from thick Ti 6-4 billets. First frames with Triton CNC yokes coming soon. 29er with 2.3" tire, 440mm chainstays and plenty of clerance for 2x10 drive


 Nice work, are these for in house use only or will they be offered to other frame builders?


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## PHeller (Dec 28, 2012)

Inspired by a 3" yoke, built a 2.5" yoke?


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## Triton Bikes (Jan 6, 2010)

PHeller said:


> Inspired by a 3" yoke, built a 2.5" yoke?


Yes, the 3" yoke did not work with the narrow Q-factor setups.
I spoke to Mark at Paragon and if there's a certain demand, they may start offering 2.5" too. But better talk to Mark


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## Triton Bikes (Jan 6, 2010)

tiretracks said:


> Nice work, are these for in house use only or will they be offered to other frame builders?


We shall keep it in house for now on.
I think the best way is to ask Paragon to make it


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## Triton Bikes (Jan 6, 2010)

Yokes integrated in the frames. Brushed and bead blasted matte.


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## D.F.L. (Jan 3, 2004)

Who are good sources for investment casting, here in the U.S.?


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