Reader Story: Building a Custom Steel Single Pivot Enduro Bike

Mar 21, 2021
by rokkrumpestar  
It s self-made by me 4130 Chromoly steel single pivot full suspension frame. Mullet setup with 155 170 mm travel and 63 HT angle.

Three years ago, I came up with the idea to make my own custom bike. For the first year, I was skeptical if I should buy a new bike rather than taking the harder path of making it myself. Despite the risks of failure, I still encouraged myself to go with the more difficult option and to spice things up I wanted to make a full-suspension frame.

I spent a lot of time on the internet learning about frame building and thanks to websites like Pinkbike I got a lot of information that I wouldn't have otherwise. All the forums and videos were very helpful at the beginning. Next, I started making frame geometry, initially on paper and then soon after on a computer where I continued 3D modeling using Autodesk Inventor. I was also using the Demo version of Linkage X3. Although you don't have access to some of the program functions it's still helpful. This process of learning, planning, designing took me about 18 months because I didn’t want to overlook anything I could later regret.


Earlier design of front triangle.
Leverage ratio and axle path.


For me, the frame is the heart of the bike, the geometry really needs to suit you well. This is why I think frames with custom geometry are just on another level.

For the material, I choose 4130 Chromoly steel because it is suitable for beginners to work with and more important its ride quality.
Specifications:

• Travel: 155/170 mm
• Head tube angle: 63°
• Reach: 490 mm
• Chainstays: 445 mm
• Wheelbase: 1292 mm
• Wheel size: 27,5" rear and 29" front wheel (Mullet)

The jig I built is from 40x40 mm Aluminium extrusions. It's kind of affordable and good for beginners. With the lathe, I also made a couple of aluminium holders, mounted on 90° joints, for holding the bottom bracket, seat tube and head tube. What I really like about it, is that you can easily change it and make whatever kind of bike you want.


For tube mitering I was using Bosch hole saws, mounted on a milling machine. Because everything was held together securely, without any movement, the fit between tubes was tight. I was relieved when I saw on the 3D model that I am not going to have to bend any of the tubes because there is a lot required to master bending those tubes. For the next build, I will make sure to try some bending to learn that skill.

Mitering hole for the main pivot.

SRAM DUB PressFit bottom bracket bearings as pivot bearings.

Next, I was thinking about what kind of linkage should I make. Given that this was my first frame I didn't want to make it too complicated, for this reason, the answer was simple. A single pivot.

Another question I had to ask was what kind of bearings should I use for the swing arm? I decided to go with bottom bracket bearings, more specifically with SRAM DUB PressFit bottom bracket bearings, and I am glad I made this decision.

They are strong, well-sealed, and I never had any problems. Also one of the unique parts of the bike is the dropouts. They are made out of 7075 Aluminum. I can easily make another pair of them a couple of millimeters longer if I ever wanted in the future.

One of the stages of making dropouts on a milling machine.

I didn't have a lot of experience welding TIG before because I started learning it like 1-2 months before it was time to weld frame. I spent a lot of time cleaning tubes before welding because it makes big difference. Tight connections between tubes are also important. Not the best-looking welds, but for the first frame I built, I am very happy with how it turned out. Because the frame jig was straight I didn't have to align the frame after welding.




I am very satisfied with how the finished product looks, and more importantly how it rides. After testing it now for quite some time I can say that the ride is impressive.


81 Comments

  • 100 0
 wow ! what an achievement ! The more home made bikes I see the more I feel the urge of doing it myself :-) Have fun riding your creation.
  • 6 0
 Same here. That recent homemade bamboo hardtail was one of the coolest things I've ever seen. Looks like such a fun project, imagine being able to say you built yourself a bike.
  • 67 1
 Somebody finally found a good use for the Press Fit BB! Nice work and good geo.
  • 10 1
 I think all pivots should use bigger, more robust bearings. Excellent idea if you ask me.
  • 7 0
 @brassinne: Large diameter bearing.. but the balls are tiny.
  • 1 0
 @emptybe-er: bmx bottom bracket bearings would be more appropriate for a pivot joint.
  • 26 0
 Respect! Anyone who tried to make their own bike knows how much work this is, especially without a mig
  • 10 0
 Mig? Welder? All metal frames are Tig welded.
  • 27 0
 @BikesBoatsNJeeps: sorry, meant jig, autocorrect f*cking me up as usual
  • 3 1
 @BikesBoatsNJeeps: TIG or Brazed, like for Starling frames
  • 2 1
 @zoobab2: Yeah fillet brazed as well although that has fallen out of favor due to all the finishing work and added weight. It is beautiful though.
  • 3 0
 @theoskar57: Ah-ha. Yeah I make temp jigs for jobs using 80/20 or just attach everything to my fixturing table. I've modified or repaired a handful of steel frames and not had to post align them just by clamping them all over on my table and then being smart about my weld placement. The real good guys can move around work and use the growth/shrink of the material to manage distortion. I'm not that good.
  • 24 0
 Donuts come in many flavors.
  • 23 0
 Since no one is mentionning the elephant in the room: No water bottle. ????
Just joking. Great job hat off.
  • 4 3
 Also no mention of it looking like a session- times have changed!
  • 5 0
 @cuban-b: I have a Session and it definitely doesn’t look like it- this looks way cooler!
  • 14 1
 Home made single edition frames are always very cool
  • 8 0
 Very awesome. 2 things.

1. Does the frame have a noticeably high amount of pedal kickback? Pivot seems higher than most other single pivots, and axle path is more rearward

2. demo version of linkage? definitely worth the $20 haha.
  • 16 0
 Looks alot like old school Santa Cruz bikes. Heckler and bullit.
  • 4 0
 Amount of pedal kickback doesn't depend only on frame. One of the factor besides frame is also drivetrain. If you ride with big cog in the back instead of smaller one, you get a lot more pedal kickback. I am not noticing much pedal kickback while riding.
  • 1 0
 @makripper: That rear triangle is straight off an 02 Bullit!
  • 1 2
 @freeinpg: mmm. Not really.
  • 1 0
 @freeinpg: yeah man it has those vibes for sure!
  • 10 0
 Bravo!!!! Well done Man!!! I really love this kind of article.
  • 9 4
 Hopefully @KnollyBikes doesn't see this. Looks like the Seat tube angle/BB placement infringes on their patents would hate for you to be next victim of their sue happy conquest.
  • 2 0
 But all joking aside, this is very cool. Well done
  • 7 0
 Awesome build. Looks realy realy good for your first build.????
  • 4 0
 There was a big jump between the last and 2nd to last picture. Can we can a part 2 on painting and assembling the bike? looks great!
  • 4 0
 Off topic, but anyone know where these pics are taken? Beautiful mountains in the back drop.
  • 4 0
 He’s replied to some posts in the comments section. Based on the flag, looks like he’s in Slovenia. I’ve heard the mountains there are amazing.
  • 1 0
 Nice job! For a first proper stab at TIG, those weld ain’t too bad at all. The main body of the weld looks relatively consistent, just the start/ stop locations which could use some love. A nice drill to practice is to weld something simple like a butt joint, but practice starting and stopping every inch or so. You’ll quickly get pretty good at filling craters.
  • 2 0
 This would look pretty cool with a clearcoat. Maybe on the next build if you use the same material and welding method clearcoat it, the coloration around the welds looks sick.
  • 4 0
 Homemade, mullet, well thought geometry ???? PERFECT
  • 4 0
 Welds still look better than an ancillotti
  • 2 0
 I wish I had the financial resources and adequate welding skills to make a bike how I see fit. Very good article! Hope to see more
  • 2 0
 Major kudos to you for not only undertaking such a project, but to have the knowledge to actually finish it. Very impressive!!!
  • 3 0
 Much respect and an awesome bike. I'm betting every single ride is just a little bit better somehow.
  • 3 0
 This is awesome! So great to read about your process and decision making. Well done!
  • 4 0
 Please feature more builds like this PB.
  • 1 0
 Price of bikes have made more and more people making their own or that’s what I’m thinking.... well maybe not, how much is a milling machine would you need to make just a bike frame?
  • 1 0
 Price and Covid-bike-bubble related bike shortages might drive people for the homegrown approach.
  • 3 0
 Looks like a Starling. For real though, this is sick!
  • 5 0
 The swing arm is very Curtis. Cool bike.
  • 2 0
 @dingus:
VERY Curtis more like
  • 2 0
 @dingus: True. Was thinking more of the front triangle though
  • 1 0
 @moduwave: that front triangle is definitely starling inspired! Looks cool
  • 3 0
 Its like a sexy steel old-school SC Bullit
  • 2 0
 Those welds look great for a beginner! And that paint is gorgeous! Good job!
  • 1 0
 There's a lot of hand-wringing and sweating that goes into me just putting together the hard-tail I've been working on. This is a wild project as a first bike! Nice one!
  • 2 0
 Red bikes are fast, homemade bikes are faster... homemade Red bikes are fasterer still...
  • 1 0
 Familiar home mountains in the background pulled me into the article. Great work, very nice result. Will be following your work closer from now on. Chapeau - kapo dol!
  • 3 0
 That looks bad ass!!
  • 3 0
 Nice one!
  • 3 0
 Very well done!!
  • 2 0
 how cool is this! hat's off: keep 'em coming!
  • 1 0
 Impressive, especially for your first one.. hopefully it won't be your last Smile
  • 1 0
 Welds look pretty good for a beginner! TIG is not an easy thing to jump in and just lay it down. Nice job on the build!
  • 1 0
 Good stuff mate, I like it. Thanks Pinkbike, more home made articles please.
  • 1 0
 Lovely. Not too distant a descendent to a first generation Santa Cruz - tazmon etc
  • 1 0
 Looks like a Santa Cruz super light... that bike (I had one) was impressive
  • 1 0
 When a company that will deliver all the kits semi-manufactured for making your own frame-geo?
  • 2 1
 It would have been better if it was 62.5 degrees
  • 2 0
 Very nice!!
  • 3 2
 And will certainly last a lot longer than any plastic bikes. Great work.
  • 2 0
 You really do have an agenda, don't you?
  • 2 1
 @dirtyburger: I'm here at praise proper bikes that are made of metal. Someone has to!
  • 2 1
 looked so amazing until it was painted red lol
  • 1 0
 Very cool, well done ????
  • 2 1
 It’s neat but what’s with the walgoose shock
  • 2 0
 isn't that a Super Deluxe?
  • 1 0
 I need to design draw and build a high pivot bike.
  • 1 0
 Fantastic execution. Your first bike? Just, wow! : )
  • 1 0
 Nicely done! It has a Ducati vibe going on that is super sick.
  • 1 0
 Way Cool! well done!
  • 1 0
 I'll buy it!!
  • 1 0
 Love that color
  • 1 0
 Bullit!
  • 1 0
 Impressive!
  • 2 2
 Well good for you.
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