Originally Posted by
niknak
I have no allegiance to any tube manufacturer. The hardened tubes from any manufacturer can be drawn thinner. The more basic chromoly will be thicker. You're not going to notice a difference if your DT is from Columbus or Nova or Reynolds if the tube profile is nearly the same.
Since you're a beginner, I'd recommend 9/6/9 top tube and down tube. Choose the diameters based on the frame size, your weight, and power. 28.6 TT is safe for everything but the largest frames and 25.4 is fine for small frames and light riders. 28.6 is my go-to for probably 90% of frames. The DT diameter should be 28.6 for small frames and light riders, 31.8 for medium frames and riders less than maybe 175lbs, and 34.9 if you're big and/or strong.
You don't say how you're constructing the frame. If fillet brazing or TIG then use an externally butted 28.6 ST. If lugs, a 9/6 28.6 tube is standard.
If you're building your own fork, go with a thicker straight HT for 9/8" steerers. No need to make your life harder by using a tapered HT. Buy a fork crown with a built in angle so you don't have to bend the blades. Find blades that have a larger lower diameter made for disc brakes. Use tabbed dropouts and the Willits IS brake mount from Paragon.
Unless you already have experience bending steel tubing, just buy chainstays and seatstays for gravel bikes. All the manufacturers have stuff for that.
Paragon makes a nice low IS mount tabbed dropout.
The biggest challenge will be getting your chainstays the exact same length and the dropouts parallel and in line with each other. With QR bikes, you could file the dropout slots if you were off a bit. With thru axle dropouts, there's no room for error.
Good luck!
Thanks for all of that- as I was saying in one of my previous posts, this is the kind of stuff that would help me the most for now- actual specs I could use for starting points in my search.
I was planning on a mix of TIG and fillet brazing but details might change as the project takes shape. I initially ruled out lugs (which would be the easiest for a beginner like me) because I thought my choice of tube sizes would prevent me to use lugs (I like the idea of an oversized down tube) but seeing the recommendations in the posts like yours and others above I am reconsidering that.
Yeah, earlier posts already convinced me to chuck the tapered head tube idea...and angled crown idea was already creeping in, saw a 7 degree crown on framebuildersupply that I kind of liked and they have the straight blades that would fit it.
No experience with bending tubes so pre bent stays it is!
Planning on using a Campagnolo Ekar groupset for the build, it comes with flat mount calipers, so the dropouts will have to be flat mount. I bought a paragon polydrop set which I will most likely try to use. Unfortunately Ekar asks for 12 mm TA so yes I am really afraid of the alignment issues you are mentioning. But there is a learning curve for everything...