After looking at the many options that are out there for a custom steel frame my mind is spinning a bit. Brand names that I've looked at include Tommasini, Pellizoli, Somec, Torelli, Pogliaghi, Zullo.
My main concern is whether or not any tube sets are off limit for me, I weight 85-90 kg and am 1,97m tall. I've got a steel frameset already (my first roadbike), which has a ST of 61cm measured center to center. Also I do like to ride hard and live in a mountainous area, so the frame will be worked a bit. No racing will be done on it though.
For instance, some of the frames that use Spirit tubes look great, but I hear that they can be a bit fragile. Should I go all the way to Zona tubes (hear they are more robust) or would SL niobium still be a good option?
I realize that it's a vague question but it would be very helpful to get some guidance by the people that have experience with this.
You've got 10cm and 10kg on me, but here's what we did in terms of design for a light steel frame that would be very stiff where it counts, but also take advantage of steels ability to flex.
We wanted to use a carbon fork with a tapered steerer, which meant either a straight 44mm headtube with an external bottom cup or a tapered headtube with an internal bottom cup. We decided on the 44mm Paragon Machine Works head tube as an external cup can always be replaced, an internal one is a bit more challenging.
We used a Spirit Megatube for the downtube- nominally 38mm but so heavily shaped that that's a bit of a misleading figure. The tube has "flats" visible from certain angles, from where Columbus bi-axially ovalised the tube (using, no doubt, an array of cunning machines). The end result is a tube that is as stiff as, if not more so, than 853 OS, but a third lighter. It's very thin - 0.3mm in the centre, so don't drop a spanner on it!
This provided a lot of surface area for the junction with the head tube, and the Paragon Machine Works PF30 bottom bracket shell.
Carrying on a theme we used a swaged 853 seat tube- 28.6 at the top, so able to take a conventional 27.2mm seat post, but 31.8mm at the bottom bracket junction for stiffness.
The S-bend chainstays are Zona, again for stiffness, and we tucked an EE Cycleworks brake just behind the BB shell.
We used 14mm tubing from the PMW dropouts to a wishbone, then 16mm tubing from wishbone to seat tube, there's no need for these to be stiff- a degree of flex is desirable.
Now those who have been paying attention will realise that we now have a 28.6mm seat tube that needs to be connected to a 44mm head tube- how are we going to do that? A bi-axially ovalised Columbus MAX tube is the answer, which neatly mates too both tubes.
We've ended up with a frame that (58cm pictured) builds into a 7.4kg bike (inc cages and pedals), and that transmits as much power as I can muster into the road, without beating you up.
It's quite an involved tubeset, and it's fillet brazed which you don't want, but it might give you some ideas to discuss with your builder.