I would rather give people the information and tools to design and print their own stuff than make a quick buck off hobbyists.
For hobbyists and smaller builders, I’m happy to print out pipe fittings yokes to help the community along. It’s $1/g which puts CS yokes at roughly $150. The cost, knowledge, and accessibility of metal printing will only get better over the next 5-10 years, so I am trying to lay that groundwork in our community.
I’m gearing up for a production run of my Strato MTB and Gravel yokes. @woodpeckercycleco and myself have made a couple frames with the yokes and I’m excited to release these into the wild soon.
The MTB yoke fits a 29er tire @ 415mm CS with a 36t clearance (non-boost). Gravel yoke fits a 29x2.00 tire @ 415mm CS with a 42t clearance (non-boost)
Both are machined in-house from 1018 cold rolled steel and weigh ~185g. Pre-mitered for BSA BBs and the plug is for 3/4" 0.035" straight gauge tubing.
Already on bikeCAD! You can reach me @strato_cycles on insta or ryan@stratocycles.com if you’re interested. I’ll put them on my website too when I have the production run done.
I’ve never weighed one myself, it’s just not that important for me. But according to Fusion 360 it’s 148 grams / 5.2 oz. Plus or minus a little bit for welds and the final cleanup & grinding I do after welding it, I didn’t model those.
It’s not a hard math problem. 6" of 3/16"x1" plate is 1.25 cubic inches of steel. So about .35#/160 grams, plus or minus a bit depending on how long/tall/thick your yoke plate material happens to be. Round it up to a half pound if you want and it’s still only going to be 75g heavier than the printed one.
My point isn’t about weight though, it’s that the 3d printed yoke is probably a lot less work/more aesthetically pleasing for almost everyone.
Konga was mentioned a couple times already, but he also has this interesting taco-bent plate yoke design. There are a couple versions, including one for plus tires. Has anyone here tried it or something similar?
I’m sure I was overexaggerating on the weight savings, but having the yoke plates in hand or konga yoke (after brazing it together) compared to the 3d yoke was night and day.
Again, for context, my yoke plates were 1/4" thick, 22mm tall, and probably around 7-8cm long (I’ll go measure later and update this post maybe).
Brazing the konga yoke together took an entire rod if I remember right, it’s been a few years.
Ultimately, the weight savings may not be important to anyone. But the time saved and the ease of using 3d yokes is amazing. I don’t have to weld anything, machine anything, shape straight edges to be rounded to make it more aesthetically pleasing, etc, etc,. The amount of steps I have to do in order to make a kickass chain stay sub assembly went from 10-20 to 5 or so and I can finish it in less than three hours with no machines available.
I was cutting my 4130 plate from a chunk I got from Aircraft Spruce. I’d cut it out with an angle grinder, square all of the sides, turn the torch on, heat it up, bend it into shape. Just those steps took a while and made such a mess in the shop from all the sparks.
If I had machines I’d use a bandsaw to make that straight edge cut, or do it with an endmill. And then use a hole saw to miter the chainstay ends.
If I didn’t use a paper layout and was more serious about using cad / machines the time of assembling the assembly would be even faster.
BFS will soon have a few options that is a builder design by Joe Best, I just need to get an order placed in this first quarter of 2023, it will be a full 3d printed for 27.5 x 2.8 @ min cs of 410 or 29x2.8@ 420 cs , 29x2.6 at 415 cs, for BSA shell and T47 shell option, and another option that uses plates and 3d printed connections will be available as well. Along with that I probable will do just a plate version that may come as straight so can be builder bent or pre-bent. My goal is to make a couple affordable option , that are readily available to ship with all the other products you purchase at BFS. Also I will be looking to supply with chain stays that are pre-bent , but that kind of may restrict to being used with only certain dropouts so I need to see in it makes sense or not. I currently already do bend chain stays for you all on order per your specs ,some of you in this discussion I have done this for, and I need to make that option more readily available this year via the webstore
Would love to here the level of interest for commercially available options or yokes and chainstays at BFS.
@BikeFabSupply, I think commercially available 3D metal printed framebuilding components is a no-brainer. No one is doing this yet. It’s overdue, really. I think one key with yokes is that the design needs to be flexible to accomodate a range of chainstay lengths. Paragon’s CNC design nailed it in this regard. It’s the yoke I’m planning to use on my next build, expense be damned. It’s gorgeous, flexible, and robust. Now if there was a lower cost printed option commercially available…
I would be surprised if the 3d version BFS will offer will be more expensive than the PMW one.
I think at this point, the PMW one will fade away once a commercially available 3d printed one is available.
Andrews specs that he posted are the min chainstay length possible, anything longer will be fine. I imagine they’ll capture 3/4" / 19mm tubing with 0.035" wall thickness.
All you’ll need to do is square ends and put in a 8-9° bend in the chainstays and miter the dropout end.
This is pretty cheap if you order that tubing from Aircraft Spruce. I’d be surprised if Andrew doesnt offer stock of the 19mm tubing once the yokes are available.
Flexibility is always good, but I think this is old-school traditional manufacturing thinking.
I have several variations of my yoke:
T47 or BSA
52mm chainline
55mm CL
Plus bike
22.2mm CS
Titanium versions
It costs no more to print one yoke design vs twenty different designs (although its a pain in the ass labeling them all so you know what you actually got )
Typically once you have your Max tire and Min chainstay established, you just very the length of this segment:
However back to @honu_hardtails original plus bike goals, a plus yoke is a different design than the 29x2.6 style yokes. IMO, to get “real” clearances with 2.8-3.0, the tire needs to be behind the chainring:
Of course you’re right, Daniel. Subtractive manufacturing is old school, but still has its place. The promise of additive manufacturing is, as you say, the ability to “print” one or many, it makes no difference. My one lingering concern about the technology is wondering if we have enough real world data on the durability of these parts. I would think voids/porosity could be a problem.
Regarding my design: my 2.8 tire is behind the chainring. It’s a 27.5 x 2.8" tire on a 430mm chainstay. Straight seat tube, not bent. See, old school.
I’m working on a bike right now using one of Daniel’s yokes on a T47 BB. I was able to fit a straight 35mm seat tube offset towards the head tube by 3mm, fitting 27.5x2.8" in 410mm chain stays. Still has 12mm from tire to seat tube. The tire to yoke fit is a bit tight, but with my Konga wheel checker and a 27.5x2.8" tire on a 46mm internal rim it has just enough space for wheel deflection.
Sorry, I was not implying old school is a bad thing, I just wanted to point out that some ways of thinking don’t translate well to 3D printing. In this case, one-size-fits-most yokes don’t take full advantage of 3D printing.
To be clear, I’m not trying to say one style of yoke is better than the other. Every process has advantages and disadvantages. With 3D printing your concerns about strength and durability are valid. No one can definitively answer that question because the tech has not been around long enough in bikes. In my opinion that is the greatest weakness of 3D printing at the moment.
Every design decision comes with risks, it’s up to the designer to determine what level of risk is acceptable and if the tradeoffs are worth it. If I never wanted a frame to dent or break, I would build it out of 3mm thick tubes, but it would ride like crap!
Nicely done, sounds simple enough hah. I have been unable to get this to work. I created a plane along the path of the inner arc, created a sketch profile on that plane. When I use the sweep command I am able to select the sketch profile and path, but when I choose the outside arc as my guide rail I get an error. I’ve tried several different sketch variations but there is something I am doing incorrectly. Any insight would be appreciated or any other sketch views you are willing to share. thanks!
Your profile should be centered on the chainstay centerline and be the same diameter as the chainstay such that the inner and outer edge of the yoke land on the edge of the profile…
Thank you! I still need to do a lot of refinement but I’m happy to have been able to get further with your help. At what point do you think you’ll be comfortable sending a design to be printed? Will you use internal lattice structure? What wall thickness? So many questions…
The more various designs that get put on bikes the more we will learn. I am excited at the prospect of getting a yoke I had a part in designing on my next frame for this seasons riding. More 3d printed parts getting real world testing.
I’m not an engineer, but that 90º corner with the small radius on the drive side of your yoke looks like a failure point. You may have to make the leg a bit longer and add a larger radius there. In general, I think 90º corners should be avoided. When in doubt, make it swoopy.
Someone with proper knowledge should chime in though.
This is what makes me hesitate to design my own 3d printed yoke. Without any real knowledge of its true strength, I don’t want to gamble with my or my customer’s safety.
I think as a collective of interested parties, we should design and print a few yokes, maybe one for hardtails and one for gravel bikes, have an experienced welder build them into a sub assembly with a BB shell and dropouts, and chip in to get them tested. If I’m not mistaken, there’s a testing lab in the Portland area. This sounds like a discussion for another thread though.
I’m just gonna send it. Got a prototype snuck into to Daniel’s last order.
I had some conversation with Kris Henry of 44 bikes about some of his 3d printed parts.
He said that 316L isn’t the greatest for shelled load bearing parts, like yokes or head tubes but that they should be at least 1.5mm wall and internally latticed. He uses 15-5 stainless with 1.2-1.5mm walls and lattice
I didn’t fully listen though, my walls are slightly under 2mm and no lattice.
I’ll build myself a frame with it, and thrash it around for a while before I use it on a customer frame.
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