Disc brake steel frame gravel build

I am gathering ideas for my first frame build, which is going to be beginning of next year at the Bicycle Academy. I want to go there with a clear vision in mind and all the choice of components already sorted out.

The idea is to build a gravel bike with a Columbus steel tubeset and disc brakes. The first two question that come to my mind are:

1. are there specific tubeset for disc brakes, or they are all the same for rim and disc?
   
2. I see the Columbus Futura Gravel fork takes flat mount brakes. What about the rear brakes, can I put a flat mount on custom steel tubes? or do I need post mount?
   
   

Thanks!

You can get specific rear stays for disc brake forces. I’m not sure how absolutely necessary they are.

Easiest way to do it on the rear would be to use dropouts which have the brake mount included. Otherwise aligning a flat mount brake and attaching it to a chainstay using a fixture may be out of the scope of your framebuilding course.

You can get Columbus chainstays which are specifically shaped for brazing on flat mount caliper mounts - SLF114OV450SX, SLF114OV450DX for the driveside.

Alternatively, Paragon make dropouts with flat mount bits you can braze onto the NDS chainstay (DR2071 in steel for QR rear end - Ceeway sell them). Or you could use Paragon Polydrops with a flat mount insert.

Or you can make it standard and then braze some flat mount caliper mounts directly onto and into the chainstay. It's a lot of work but I think it looks best. This was my recent effort:

That looks gorgeous, congratulations!
I don't think it's something I can achieve in my first build though.
I can't find the chainstay you recommend on the Columbus website here: https://www.columbustubi.com/eng/4_4_6.htm
Where did you read that they are shaped for brazing on flat mount caliper?

Following up on @PhilDAS's recommendation as well, I am guessing a dropout with brake mount is the easiest way to go. In that case, should I still look at flat mounts? Would it be weird to have flat mount brakes on the front fork and post mount on the rear dropouts?

Would it be weird to have flat mount brakes on the front fork and post mount on the rear dropouts?

awkward with pads etc

what do you mean? in what sense awkward with pads?
I am thinking about Paul’s klampers, which come in both versions

Most flat mount brakes have smaller, different pads to the post mount version.

So you would need two sets of spares.. maybe that’s not awkward to anyone else.

In our house all bikes are aligned, road bikes are hope hubs, Shimano 11 speed with the same bbs and headsets etc.

We have a tandem and touring bike, identical wheels brakes and drivechain. - also partly due to when the tandem is outgrown I have a spare surly frameset to build onto.

Love the klampers but why not go hydraulic for that money?

This was built by Tom who teaches at the bicycle academy

It’s Columbus Zona and flat mount at the back. I used some old post mount forks that I had for the front. The Academy has a load of Columbus Carbon flat mount forks in stock at the time.

I wanted Zona and Tom thought it a wise choice for a bike that would be treated roughly.

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why not hydraulic?

All those fluids, the rebleeding and stuff, it makes me squeamish :D

Maybe you'r right, it's irrational, but I really love that amazing mechanical craft of the Paul's Klampers.

Are you saying you have flat mount on the back and post mount on the front? Interesting, because I was thinking of doing the opposite myself. Do you have a picture of the flat mount on the back? I'd love to see how it's brazed on the chainstay.

Nah, you have been sold a myth.

Hydro brakes rarely need rebleeding and unless you are unlucky you rarely need any interaction with the fluid.

— also, I have done a TBA course, all of these questions may be better aimed at them as they are your guides and tutors to what is feasible in that week

I believe columbus have a new range of forks about to come out once they get over their anniversary. I would go flat mount hydraulic if i was building one myself.

I only went post mount at the front to save on buying new forks. I would rather go flat front and back and hydro

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Fair enough, I should ask them. But I am still very confused about what I want to build (too many ideas in mind and only time for one bike :D). When I have slightly clearer ideas, I will contact them.

I still believe Paul's Klampers are a beautiful piece of engineering, but you're slowly convincing me towards hydro :D

Thanks for the picture! Is that a Paragon dropout then?

Interesting, interesting... where can I read more about the new forks?

are a beautiful piece of engineering

100%, absolutely stunning

I was told by my frame builder but i cannot see anything online this morning.

The Futura Cross from their 2018 catalogue looks new to me, I haven't seen it yet on any bike, see pages 8--9 here: http://www.columbustubi.com/pdf/Columbus_2018_Carbon_Catalogue.pdf

No idea...that query is above my pay grade:)

Hi. Planning a build myself and was looking at this flat mount solution. Can I ask what spec chain stays you went with for this? There seem to be some disc specific ones from Columbus that we double butted with a thicker wall at the tail for the disc loads, but they’re pretty chunky things. All the other tubes I’ve seen are single butted. Is that OK? Prefer the aesthetics of the slender tubes. Thanks.

Those were Columbus Max chainstays, so still pretty chunky at the BB end. They've survived doing Vienna to Barcelona, so they seem up to the job.

Thanks Dan. Looks like there are a couple of Max chain stay types. Any idea which one you used?