Thank you for pointing that out Daniel. I already ordered the tubes but I guess I’ll be returning/making a new order then. I forgot a front derailleur hanger anyway. You live and you learn!
As far as the DT goes, it is straight gauge .035" wall 4130. For my personal preference/risk tolerance I’ve decided I’m okay with that. Despite the wide tires, I don’t think this bike will see much singletrack or really rough roads. But I still appreciate the input. I’m here to learn after all.
In my last post I mentioned trying to fit the front triangle shape to a frame bag I had. I’ve abandoned that idea. It would alter the geometry too much.
I’m doing my best to keep this a parts bin build. As tempting as it is to buy nice components, I will try to use what I already have. An interesting development though. I have a microshift 9 speed groupset with both brifters and trigger shifters. This means I could swap between flat bar and drop bar. This bike was originally going to be flat bar, but having the option to try both seems very nice. So I shortened up the reach a little bit. Now it can be a hybrid or a gravel bike. Of course this means long stem with the flat bars, but I think that might look cool anyway.
I have no 3d cad of this bike. But I still wanted to see how it would look so I put it in the free version of bike cad.
As @Daniel_Y pointed out, the last seat tube I had chosen was for lugs. I will place a new order for an externally butted seat tube, as well as some seat stay tips. The microshift groupset is 1x so no need for front derailure mount. I’m going to wait a day or two before I hit order this time haha.
| Frame Bill of Materials | ||||
|---|---|---|---|---|
| Component | Description | Link | Price | Vendor |
| Head Tube | 1-1/8" HT stock | already have | ||
| Top Tube | 28.6 OD, butted | link | $16.00 | framebuilder supply |
| Down Tube | 31.8 OD, .035 wall, straight gauge | already have | ||
| Seat Tube | 29.8 OD top, 28.6 OD bottom | link | $27.00 | framebuilder supply |
| Chainstay | oval: 30x16 to 12.5mm OD | link | $38.00 | framebuilder supply |
| Seatstay | 14 OD top, 10.5 OD bottom | link | $30.00 | framebuilder supply |
| Dropouts | lugged | link | $35.00 | framebuilder supply |
| BB | 73 width | link | $7.00 | framebuilder supply |
| seat stay tips | for 12mm ID | link | $15.00 | framebuilder supply |
| cable guide | link | $10.00 | framebuilder supply | |
| disc tab | link | $8.00 | framebuilder supply | |
| bottle bosses | link | $4.00 | framebuilder supply | |
| seat collar | link | $7.00 | framebuilder supply | |
| Total | $197.00 |
and here’s an ugly 2d drawing of the bike
Excited to start cutting some metal.
Not related to this build, but seeing as this is MY THREAD and I’ve already posted a giant fidget spinner here I will post this as well.
This is a thru axle designed to mount some flanges that a rack would mount to. I made it for a friend and it’s his design not mine.
The axle goes through the frame and a ‘nut’ threads on to the portion of the axle sticking out the opposite side. The nut, as well as the head of the axle have a 6 bolt pattern on them which the flanges will screw onto. A little confusing but I’ll ask him to send me pics when it’s on the bike.
This is my first-time machining something sort of complex that someone else designed. I look forward to seeing how it works.
One of the reasons I wanted to make custom bike frames is to be able to try wacky and weird things. Speaking of wacky and weird, I’ve made a last minute design change. I’ve always thought integrated seat posts were cool. So I’m going to leave my seattube extra long as a pseudo ISP. If I don’t like it I can always cut it down later.
Anyway, I have the “U” put together and fully welded. My plan is to do the rear triangle, then position the top tube so it lines up nicely with the seat stays. That brings up another discussion topic:
On a bike that has an upright riding position (like this one), you have the options to have a sloping top tube, or a more horizontal top tube with a spacer stack. AESTHETICALLY speaking, what do you guys think about these options? I think too many spacers looks like you have the wrong sized frame, but too sloped of a top tube gives a more mountain bike look that I’m not going for.
sloped top tube
Horizontal top tube with spacer stack
I guess the third option is to have a tall head tube AND horizontal top tube like a vintage road bike but then you lose standover height so I’m not considering this one.
I design around 25mm of spacers, and build up the bike with 30mm. I found this to be a good balance of adjustability, bar height, and aesthetics.
The other two considerations are seat post flex and standover: Some people want the racy look with zero spacers, but they want high bars. This results in a goofy-looking bike with minimum seatpost flex and an awkward standover.
I would say a slight slope to the top tube (<6°) will be hardly noticeable and gives you a fair bit more stack/less spacers. The straggler there looks fine to me with 40mm of spacers and what looks to be 110mm stem. A shorter stem might need for a few less spacers to look proportional. A taller headtube extension is worth considering if you really want to go for the level top tube look. Disc Trucker has that feature if you want an example, albeit with a sloping TT (roughly 4° I think).
Aka the vintage road bike.
I never considered how stem length would factor into the proportions of a bike. That’s a great point.
Made some good progress recently. I ran out of acetylene in the middle of the TT ST joint, and the TT HT joint is only tacked but other than that the main tubes are all together. Since I believe I’m equally skilled at both (mediocre at both), I used both tig and brazing depending on what I thought would be easier/better for that particular joint.
My rear triangle jig worked pretty well. Much better than last time. The one major issue with this setup is adjusting it is very cumbersome. Once everything is in place, it’s very solid and easy to get a frame in and out of.
This was also my first time bending as well. I used this 3d printed bending die and it worked great. I think I put the bends a litte high up on the seat stays. There’s an exessive amount of clearance compared to the chainstays. Hopefully my thighs don’t rub on them.
My acetylene regulator busted so I wasn’t able to finish the bike this weekend like I planned. I still need to add a disc tab and cable guides. Of course, I couldn’t wait to slap some parts on it to see how it would ride/look.
Low speed around the block felt good! The only negative is toe overlap but I knew that was going to be present. I tried both flat bar and drop bar. Both would work but the drop bars look slick. I might be going in that direction for the build, at least for it’s first iteration.
I’ve also been thinking about finishing. I had the idea of clear coating this one, but making my fillets look clean is a real challenge. Paint hides some of the imperfections. This bike might end up being yellow, like all my bikes.
Really cool bike, I like the look of the dropbars.
You should clear coat the bike, I think it would be a shame if you hide all your hard work under paint. And if you don‘t like it you can still paint it yellow next year… 
The frame is done except for the coating.
Thanks! That was originally what I wanted to do but my lumpy fillets do not look good. Imperfection is art though I guess 
. I will think about what I want to do.
Time for a ride report!
I’ve had the chance to put some miles on my new hybrid/gravel bike. Overall very pleased. The handling is snappy and it eats up rough terrain. As far as flat bars vs drop bars I’m leaning toward drops. I have some old skinny road bars on there, but I have some wider flared drops in the mail. We will see. I’ll get some actual gravel tires on there at some point! Open to suggestions. Vitoria Mezcals maybe?
Also, not framebuilding related, but bike and fabrication related so I’ll post this mod here. Gives me some extra ground clearance for my bike rack.
RIDE REPORT
Nice. How is your FS bike holding up?
Thanks for asking. That bike has held up well. No cracks or anything and the linkage works smooth. After putting some miles on it there are things I would change. Most critically, there is not enough tire clearance at the seat stays. It’s too easy for mud and stuff to get caked up in there. The seat tube angle is also steeper than makes sense for me, and the head angle maybe a touch too slack. The suspension works great though and the bike still monster trucks over obstacles. It’s not a great jumper due to the super long chain stays but I don’t do much jumping anyway.
I wanted to share my current project. Framebuilding related. Arguably bicycle related.
I’m working on rebuilding a 70’s moped. It’s been a fun project, and a fun thing to ride. I think of these as the original e-bikes. They’re different than what most people would consider ‘mopeds’ nowdays. They have a pedal drive and components more comparable to a bicycle rather than a motorcycle. I wouldn’t ride it on a bike path since it’s loud and stinky, but aside from that I use it the way many people use ebikes. If you’re mechanically inclined, they can be a cheaper alternative to a class 3 ebike, at least until ebikes become cheaper.
I made a new frame for it, re-using the motor mounts and some of the components. I designed the frame to be very bicycle like and minimal. Aesthetically, I wanted it to have the silhouette of a little motorcycle, but with an emphasis on how simple of a machine it is. Body positioning is different from a bicycle. I don’t need a perfect seat height since I have a motor assist, so I can drop the seat and controls down to get better handling and be able to flat foot it at stops.
I’ve done lots of work, and have lots more work to do on the engine and components, but that is a topic for a different forum . Overall I’ve very happy with how the frame turned out and I look forward to continuing my framebuilding journey.
It’s been a while since I’ve done any bike fab stuff. But it’s getting colder and the riding season coming to a close.
I’m ready to start a project that’s been on my mind. I want to build a cargo fork for my gravel / commuter bike.I’ve never built a fork before so any advice/input is appreciated. These are the parameters:
425mm axle to crown
39mm offset
100 x 9mm QR axle
1-1/8" straight steerer
disc brake (yeah I know QR disc brake. gross. but it will go with the wheelset I have)
integrated rack
water bottle bosses on the sides
clearance for 700c x 38 or 27.5 x 2.2
One option I’m considering is using this fork crown with 60mm spacing along with straight blades and custom laser cut dropouts to achieve the somewhat non-standard offset. The big concern I have with this method would be stress concentration or loss of strength where the rack is welded or brazed to the fork. The ms paint drawing below shows the sort of design I’m planning on going with.
I will keep thinking about my options, and I appreciate any feedback from the community.
