Will 3D printed MTB parts break catastrophically? Let's find out! 

I didn’t upload my designs because these are actual bike parts that could fit on a real bike. I’m not so sure it’s smart to put them out there. Also, I’m not sure why I referred to the hex size in the axle with an M before it. It is just an 8 mm hex.

Just wanted to say that instead of printing screw threads, you can design a hexagonal hole to accommodate a metal nut on the other side! It makes it way less susceptible to snapping, cracking and stripping the threads, plus it's really easy to do. Also, layer orientation and perimeters matter!

If you ever want to do a followup, here are some ideas for improvement: Use heat-set inserts and/or slots for metal nuts to better secure screws. Make sure your prints are designed to be printed in an orientation that optimizes their strength in the direction you want, as a print is more likely to break along a layer line. The best way to think of it is that 3d prints have a grain, and the orientation of that grain matters for the strength of the part. Change material. Nylon would probably work out as a better material than PETG, and if you're already doing that, you might as well look at the carbon fiber filled nylon that's out there. If you want strength, perimeters are more important than infill. Perimeters are where the print gets most of its strength from. From the what I can see in the video where you show the broken stem, it looks like you opted to up infill to 95+%, but didn't really add any perimeters. Try more perimeters. There's a CNCKitchen video where he tests this if you want some explanation of why perimeters do more than infill for strength. Just a random note that you may already know since you've been getting into 3d printing: Try a 0.6mm nozzle. You can still print at 0.15 and 0.2 layer heights, but the perimeter will be thicker, which makes the print stronger, and it'll print faster due to being able to push out more plastic. These days with arachne perimeter generation in both Prusa Slicer and Cura, there isn't really much of a noticeable quality difference.

I really love that you are exploring 3d printing. Some helpful advice: To make stronger parts you have a variety of options besides make the part bigger. You can choose different materials like abs, nylon (pa) and polycarbonate (pc) or materials with carbon fiber in it but especially pa is lot harder to print. There are a lot more industrial grade materials but they are way more expensive. Igus has also some really nice filaments you can use for parts that benefits from self lubrication. The orientation of how you print it is also very important. 3d printed parts tend to break first between the layers so you can use that to your advantage. You can also print more bottom and top layers as well as more perimeters. I usually print 5-7 bottom/top layers and 3-5 perimeters. Infill of course is also an important factor. 3d infill like gyroid ist usually pretty strong and around 25% infill gets the job done quite good for an average use but you can go way higher if you want it as strong as possible. And for the threads even though threads that are cutted or printed right into the plastic can hold quite a lot you can also design the parts in a way where you can use a washer and a nut or you can take a look at heat-inserts. They work quite well and are getting more and more established in 3d printing and are really good to use at parts that you screw and unscrew regularly.

Seth, thank you! Thank you for providing us with this diverse yet always high quality and interesting content. I have been watching your videos for so long I could have never guessed back then that I will witness this channel growing so much! Especially loving the 3D printer content since I have been tinkering with mine for almost two years now and it still fascinates me! To have better threads I can recommend "heat set threaded inserts" which are basically metal threads that you can melt into your print after it's done. I like that you made some parts that don't make much sense to 3D print because that is how you can learn what the machine is capable of. I used to break parts that did not fit so I could better understand the material. I cannot thank you enough for the entertainment you provided me and the things you taught me in all those years. Best wishes from Germany. PS: I am amazed at what you created with thinker cad although it's such a simple program. I can't do that much with it. I am using fusion 360.

Make rock shox tockens please

I've actually been printing bike parts for my bike for years. I've been into 3d printing long before I got into bikes. It's just that I've never printed any crucial parts that you did! I've done bike handles, bike pannier adapters, phone holders, truing rigs, and currently a low profile bottle cage. Clearly you were just having a good time here, but 3d printing is really good when you know its limits!

I agree I don’t think I would 3d print high stress parts like you did on my mtn bike. But guards and fenders and such would be great. Also the other great thing about 3d parts is you can just print another once you get a design you like if it breaks.

Too funny! I have a print farm and do a LOT of my own designs but I also know what the limitations and design according to those. I know this was just more of a PSA video and was super fun to watch. Thanks for having some fun with it!

If youre allowing metal bolts you might as well allow embedded nuts, that probably could make the seat post clamp and grips work

I would add to that last statement. "don't print Load Bearing bicycle parts". There's a good chunk of non load bearing parts you can print. And in tpu you can print slip on grips, crank boots, chainstay protectors etc.

The only practical 3d printed bike parts I've seen people make online are, BMX peg sleeves, bar ends, bashguards for your bottom bracket area, peg plugs for flatland BMX, and hubguards.

I have made and been using a 3d printed brake handle (+adapter) for my commuter single speed bike for more than a year now. It's been working perfectly without any issues 😄

That bar stem had me on edge. That could have went bad. Great video! And remember, you didn't fail, you succeeded in finding what doesn't work!

Hi Seth, Try using different material filament with your 3d printer, can be more difficult to print but wayyyy stronger, like nylon or abs. Can also use stuff like TPU which is actually elastic, so could actually make decent grips!

Of all things, I think this clip shows how much thought, effort and testing is being done for every part of the bike we ride. Being able to manufacture a part doesn't mean that part will function as expected. One important lesson from this clip - be careful what you install on your bike. Make sure it's trust worthy. Your life might depend on it.

There are metal threads that are designed to be used in 3D printed parts. You print the part normally and then use a soldering iron to push the threads into the part. It you add nuts to the bolts you can increase the strength even more.

Hey Seth, print orientation in the slicer and how it it laid out can change where you want the strength can be, based off of the orientation of the layers. Also, different pattern of infill can be stronger in certain circumstances. Overall I’ve found that gyro infill is the strongest overall but takes a bit longer to print

Hey Seth, thank you for the excellent content and the good entertainment. You bring joy to the lifes of many with what you do.

I love 3D printed parts. But not structural ones. I've made in my life 3d printed GoPro-style mounts for front light or phone holder for Zwifting, Garmin mounts, cable holders, multitool and pump holders, front mudguard even. It was a lot of fun and most of them I keep using on my bikes.

Props to you for having the guts to try these 😅 such a great idea for a series

Awesome! Thnx for the experimental cycling!

Super! This gave me the idea to print some grips in a PETG/TPU combo

Your videos are incredible and family friendly and i love to watch them. I wait days for your videos to come out

I 3d printed a set of adapter discs for adapting Flow snowboard bindings, to an old Burton snowboard. And I thought that was a crazy experiment. They blew out on the first run, but they were fun to try.

Dogpiling onto the heatset insert suggestion. They are surprisingly strong, much stronger than you'd think. Part orientation is a big factor too. Increasing shells/perimeters & top/bottom layer count will give a greater increase in strength vs infill percentage.

I've never been so stressed watching you do sketchy stuff as I have watching this video of you testing these parts.

Every one of these 3D printing vedios is Seth just breaking stuff😂

Like others have said, instead of screwing into the plastic, you can use a hex nut and also threaded brass inserts you use with a soldering iron to add the screwings:D

Seth I’ve been watching your channel for a few years now. I just wanted to say your videos are very well thought out and funny. On a cinematography standpoint these videos are great

A few of those parts could definitely use a few more wall and top bottom layers to get better strength. But still a really cool video and im glad to see your bring the 3d printing hobby into biking. Not sure if you've found the treasure trove of parts out there for the 24th scales yet but that's also a whole lot of fun!

For the screw threads, look into brass inserts that you use a soldering iron to fuse it into the part. Just look up 3d printer inserts there are good videos on it. And also, make sure it's printed at 100% infill in concentric infill pattern cus it's the strongest in all directions at 100%. Also keep in mind print orientation with the layers

Nice video, I admire your courage on taking the stem out for a spin around the track. I have 3D printed the rear cassette spacers myself a while back. Till this day i haven't had any problems with them haha. Grtz from the netherlands.

This video was so awesome! And the cinematography is so professional your videos look so good

This one was fun, but would love to see a video on actually useful 3d printed parts.

petg tends to shatter just as your parts did, pla+ would have survived a bit better as it can flex more. Plus it looks like you printed at 50% infill some of those parts should have been 100%, Another thing to think about is what side you print them on, you want the print lines 90 deg to the direction of the force.

3d printed some bikepacking dry bag holders for my front forks. They have worked great, just make sure to print parts out of ABS not brittle material

Understanding material properties is a key pillar of engineering that was omitted here 😁 The lock on grips could really have a future for riders like me that need some really oversized diameter. Built up much thinker and wrapped with roadie bar tape, could be a comfortable solution

Would really like to see this done again with something like carbon fiber nylon and some of the more well known methods for designing these things for strength.

The amount of production and value going into the second channel is awesome, this video was really good. Keep it up Seth!

For some of those parts - especially the stem - you might want to look into lost plastic casting. You can make a plaster mold from a 3D printed plastic part, bake it to remove/burn away the plastic, and then cast molten aluminum into it: then you end up with a perfectly fine and safe to use aluminum part. It doesn't take much to melt and cast aluminum. Or even brass - a brass stem would look pretty cool, I think! Also: the jockey wheel should work, as you noticed, but PETG isn't tremendously wear-resistant. Nylon is a better choice. Weed eater line is made of nylon and it works fine for 3D printing - 0.065" should work fine if you adjust the filament flow rate accordingly; in my corner of the world, we get those in metric units, so I used 1.8 mm and it worked fine out of the box - but for best results you should dry it first. Nylon is very hygroscopic. This also applies to purpose-made nylon filament that was left exposed to the atmosphere.

The horror movie music during the stem breakdown was... I mean... You're so damn creative and that creativity in collaboration with you doing video and all... . Great work, Seth. Never thought I'd be so drawn in to... a 3D printed, themed...MTB Video., on... RU-vid. Bravo.

Best use of 3d printed bike parts is definitely for mounting shifters to odd handlebar sizes or those hold anything cages for bikepacking

I have printed pedals before for my DJ bike and it worked perfectly, it depends on the design, the part, and the material you use

Nice, I will have to try some of these out! I think you would have better luck with Carbon fiber nylon. Let me know if you want some pointers on how to set it up, your printer should be able to handle it if you install a steel nozzle, it's pretty easy to do.

To correct the chain line on a 3x to 1x conversion, I designed a spacer for the Shimano Deore M6100 crankset to offset the chain ring by 7mm. Printed in PETG and attached with longer M4 bolts. I was sceptical, but it holds up really well so far, tested it by giving it all the torque I could pedal. In this case, the main load is held by the bolts tough, the plastic part is sandwiched between the spider and the chainring.

I highly recommend considering hexagonal nuts or heat set knurled nuts. If you really have to screw into plastic, don't print threads, print a cylinder just slightly bigger than the inner diameter of the bolt/screw shaft, it should be slightly big enough to accommodate the volume of the blades/teeth of the screw/bolt, and thus avoid putting pressure on the part, which might weaken its ability to hold onto the screw/bolt's threads.

Head tube spacer might be fine, no real stress that could crack it. Love the color it adds. If they could make those various metal parts in color that wouldn't wear off, I'd totally buy them.

Hey, Seth your infill % can also help with making some of those stronger along with what other people have commented talking about infill pattern and the orientation. Love watching your videos and seeing how you use your Prusa printer to make all sorts of things to try out as bike parts or other ideas.

Your vids are they best. There really entertaining and they inspired me to start mountain biking

I designed and printed oversize (15T) jockey wheels for my RD-m8000 derailleur. It fits in the ceramic bearing from genuine Shimano jockey wheels and printed using PLA. Each of the wheels last over 3500km before wearing out. I enjoyed extra derailleur capacity and custom color, super fun!

Some of these would probably work with carbon impregnated filaments or carbon reinforced prints like Markforged has. Unfortunately they're super expensive printers lol. Metal can also be 3D printed using laser sintering. This can create parts with little to no post processing or machining required, but is also very expensive.

Out of all these things I think there's actually super usefull usecases for 3D-printing the stem! It would be awsome for testing out the feel for different lengths without having to buy a bunch of them. (I mean you'd have to oversize the shit out of them, and not take them out on a real trail, but it should give you some idea of what will happen to handling)

This video was awesome! The timing for the stem breaking was wild If you revisit this please try 3 things: 1. PLA+ is in a lot of situations stronger than petg and even carbon fiber nylon so give PLA+ a try 2. You can add slots for nuts or use heated inserts to make connections stronger 3. TPU would make nicer grips

THAT, was hilarious! Yes, you confirmed what we already knew, but it was the most fun I've had today. Now, I DID make some specialty parts for my own bike, but it was a set of mounts using screws and nuts, and a housing for a switch hidden under my cargo rack. Thanks for the video!

From someone with a masters degree in 3D printing, I found this really entertaining. You're right, there are design aspects that affect the part's performance, but there are also factors like print orientation and material that are big factors. I'm assuming you printed these solid, but infill also plays a role. It'd be cool if you had access to a metal printer or the Markforged which can add carbon fiber inside the prints.

There’s definitely a guardian angel looking out for you at 8:48 when that 3D printed stem decided to break! 😂

LOL, yeah that was bold and impressed that you actually rode it. I make non-critical bike parts (always print solid 100% infill). Also nylon or filament with carbon fiber will probably work better. But I still would not use myself as a guinea pig!

The problem is not the plastic printing, the problem is the design. I like what one person said: "design is ten times more important than material." printing can be produced with reinforcing materials, creating a composite. use glass net, metal net, or other materials. in conjunction with the correct volumetric design - this will give the necessary result, but I'm not sure that this will work for downhill)

Seth: it's time to be smart and ride a little safer to avoid injuries. Also Seth: does this

You can buy Nilon filament which would improve the strength of the parts. However you would need to upgrade the extruder so that it can melt the nilon. You’d also probably need a glass case for your 3D printer as you wouldn’t want to breath in those fumes haha.

Brilliant video, loved this.

let's be honest. You're not playing with plastics, you're designing stuff for alloy but branded by you guy! Get it!!!

Plastic is good for prototyping. But need metal 3d printer...with titanium filament.

Your designs are alright, but definitely have some flaws - the seatpost clamp would have easily been strong enough if the outer section was thicker and you added perimeters, which will generally support the majority of load on your parts. For anything load bearing you should use at least 4 perimeters, infill doesn't really matter much except for large compressive loads on the top and bottom surfaces but generally 30% is the most you need - 3d print layers are very strong in tension, but the adhesion between layers is comparatively extremely weak, keep this in mind when designing and choosing layer orientation - for threads, if your are threading the plastic directly, you definitely need a lot more material/perimeters around the threads. If you are using anything bigger than 10-32/m5 you should really tap the threads beforehand as well - honestly for threads you are better off inserting hex or square steel nuts as it distributes the force much better and will generally be far stronger without needing excess material. There are also brass heat set inserts you can put in using a soldering iron - while it's counterintuitive, for parts like an axle which are under torsion and tension, you should actually print them laying flat as the lengthwise extrusions will be far stronger than the adhesion the layers - the sprocket and disc brake are never going to be good candidates for 3d printing in plastic due to the very thin profile and concentrated loading situation they are placed under. However for something like a disc, adding holes can actually make it stronger because it will create continuous perimeters from the center to the outside, you can see this kind of optimization in metal disc brakes, though they just do it to save weight/material - if you needed it up slightly and added a lot of perimeters, the stem would have also been perfectly strong enough as well - PETG is great and more impact resistant but is objectively weaker than PLA. There are others with similar strength but none as easy to print as PLA - lastly I would recommend that you stop using tinkercad and find a real cad package like fusion 360 (free) or SOLIDWORKS which I recommend but is not officially free. Tinkercad is just a dead end software and not conducive to improving your skills

I made a 3d printed derailleur hanger for my wife's yuba (2 month delay for the part...) And it worked for 300km of commuting I think!

This video is definitely among my top 5 from your channels

First comment

I have redesigned the jockey wheel for my deore shifter to fit a 608zz skateboard bearing. The original shaft of the bushing is 8mm as well and fits like a glove. It is super smooth and made the shifter better than when I bought it. Have 1000+ km on it and it doesn't show any signs of wear really. Looks pretty much brand new besides the oil. I printed it in PETG btw ;) 100% recommended, that is something that is actually better than the original.

Havnt rode a mtb in years, but I still watch your videos for entertainment, I had a shit day today and you got my mind off it a bit, cheers bro

I successfully printed a bushing for a horst link on my bike. The factory bolt backed out and was lost. That with a flat head M6 bolt, printed using FormFutura CarbonFil Filament. It worked great until the replacement arrived. Rode about 150km with that part. You're a brave man for attempting the parts you did...

You know, I had a feeling I knew exactly how this video was going to go as soon as I saw the thumbnail. Did not disappoint

Your last 3D Printing video is the final nail in the bucket. I now have a 3D printer.

Zack Gerber have had some success 3d printing BMX bike parts like BMX plastic peg sleeves and grind pedals plates.

I laughed so hard when the rotor exploded 😂

By the disc rotor fail, I was laughing out loud. So. Many. Fails. Thanks Seth!

I printed spacers in axle rear-shock (stark devolution - 200mm) - and all OK for 1 year! Also spacer between bearings in rear hub - norm works about 2 years. Plastic norm works on compression, not bend or stretching

definitely found that entertaining! I was rolling when you threw on the chest piece.

This was cool to see, thanks! We need a part two! Maybe even with an actual engineer to advise on how to design the 3d printer parts for more sturdability :)

Mechanical engineer with 3D printers who also rides bikes. Things I would/have 3D print(ed): bottle cages, custom tool mounts for emergency tools, custom mounts for lights/cameras/electronics, jockey wheels (as a short term fix while waiting for parts, it likely won't break, but it will wear quickly), and even small pry bars print surprisingly well if you use the right orientation. Things I have turned down when the local bike shop asked: Anything involving brakes. They agreed when I told them that my printer can only do plastic. I don't have the funds or power supply to my house to run a metal 3D printer.

the great thing about this is you can test the prototypes to see if it functionally possible and can withstand minimal stress. You could then utilise the 3d printer and a stronger filiment to acctually make viable parts. potentially making cheap emergency replacement parts that can safely get you back to the car/home (provided they dont go to hard core)

Very entertaining. You are right the design of the model is important for strength, but so is the way it's printed (e.g.: number of perimeters, layer orientation, temperature, etc). Another huge factor is material choice, for this application there are materials that would be much stronger than PETG. Nylon, Carbon Fiber infused filaments, PA, TPU would be interesting to experiment with. All much harder to print than PETG.

This is pretty neat! I did a similar thing back in June, I printed a front sprocket out of pla for my old gates carbon drive equipped bike. Actually worked surprisingly well, I think I got about 90km+ out of it before it cracked. Wasn't very efficient though, and made strange noises while pedaling. Beats paying 70€ for a new one at least. I contemplated doing the same for a chain driven bike, but thanks to this video, I now know that that's a bad idea.

Use speciality filaments like TPU for the grip to give you squish. There is also carbon impregnated speciality filaments that will significantly improve the strength. You just need to upate your printers hot end for some of these filaments. But still worth a try, perhaps in the future.

I needed this video today.

Heatset inserts!!! Look up rutex brand Also, look into a hardened steel nozzle for you printer, and carbon fiber infused filament for stronger parts. Maybe worth a part 2!

Big fun - thanks!

Markforged make some printers that can use filaments containing chopped fibres and even lay continuous fibres within the print. That lets you make a form of engineering composite on a desktop 3-D printer! (Post-processing the stuff is super sketchy, though.)

I was lol'ing hard when that plastic brake rotor snapped...the music cut was just perfect 🤣

You know, if you extend the lock on grip, use a hex nut, and move the screw to the inside, youd be able to put actual grips on them. Then you can have multiple pairs of your favorite grips you can quickly swap onto different bars. Make deciding what grips you want much quicker and cheaper!

I haven't laughed so hard in a while, once the rear brake exploded. Thanks for the videos!

Colored cable bosses, custom cable/hose management, fenders, multitool holder. Some things I think would work well 3D printed. You could also probably get different filament that is more elastic, so it would be more resistant to cracking.

I broke the idler pulley on a fairly old derailler (Sram X5) and couldn't find a spare online. So I 3d printed one out of Nylon, which thanks to the low coeff of friction worked even better than the original one ! So i modified it to accept a bearing and now I basically have a sram X7 with pulley colour matched to my bike ! Also when I converted to one-by I would get chain skips (of course my sram X5 now X7 doesn't have a clutch), so I 3d printed a retainer ring that bolt in place of my smaller front cog and no chain skipping since !

I worked in plastics for 15 years, for parts intended to be durable we used giant Injection mold presses to make said parts and even used metal inserts to anywhere a bolt was intended. I have never tried this but was told, The press used determines the overall strength of a part. the way that works is a higher press number (usually measured in Tons), the more plastic is pressed into the mold. the total tons of the press is both the press holding the mold together as well as the pressure of the feed and Screw assembly. The more plastic and less air, the tougher the part can be made. That said it's still plastic and of course has it's limits, hence why it's almost never used for stress or structure parts. The issue with 3d printing is there is no compression of the plastic for strength, just one layer on top of another. There could be air pockets, carbon buildup (From the tip) falling into it as well as any number of impurities from the air contaminating it. This is why 3d printing is used for light work, prototyping or decorations, it has no real strength. All that said, it was interesting seeing it done and glad you didn't get hurt

One actual part i have been running is headset spacers since they don't take alot of load after the stem is tightened. The main benefit is you can get you bike fit sub millimeter perfect

"Today we're doing something a little different, but kinda the same. I have some lego bike parts here, and we're gunna check em out"

These would be great parts to use as patterns in Lost PLA casting.

That was entertaining. Will there be a part 2?

Great video.. I'd like to see you print the parts in carbon nylon filament or glass fibre nylon. Just to see if those filaments are as strong as people suggest. Very entertaining. Thanks

So, I am an Additive Manufacturing Instructor for ATDM. I absolutely love this idea. I have yet to combine my love and career for 3D printing and bike riding. I would love to design and print some of these parts. I can ensure that the prints I could get will withstand 1500-2500 lbs of force, which is more than enough for bike parts. You could send me some of these files and I could mail some sample parts in. I have yet to ride Berm Park yet, but maybe this could be my reason to come. Bring the parts, and ride the parks.