I am a frame builder AMA

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  • I don’t fully understand your question.

    Most folk avoiding the greater heat of brass do so to minimise heat distortion with thin-walled tubing.

    For clarity, the intergranular corrosion issue is within the eutectic silver braze material, not the stainless. If the braze doesn’t get exposed to chlorides (e.g. road salt, sweat), then deterioration is slow to nil. Shiny stainless ridden solely on sunny Sundays won’t ever come apart.

  • You said that some framebuilders swapped from silver to brass. I didn’t think you could braze stainless with brass so was asking if it’s that you can braze stainless to stainless with brass but that to braze stainless to other types of steel you have to use silver. Like a stainless track end into a mild/chromoly chainstay, that would need to be silver?

    Separately, 6 months or so ago if you asked me if you could braze stainless to anything with brass I’d have said nah but then I read something about bicycle tubing being like a really shite version of stainless and that it didn’t adhere to the characteristics of truer, higher quality stainless. Since then I’ve used brass to braze some shit stainless to some other shit stainless so I knew that worked but still wonder about stainless to non-stainless.

  • Brazing is just a hot metal glue. With the correct preparation (allowing wetting), you can braze lots of materials together. There were (rare) brazed aluminium and brazed titanium frames last century. What makes you think that you can’t braze cro-mo or mild steel to stainless or stainless to stainless with brass?

    Many folk silver braze stainless tubing because the stainless tubing was high strength and very thin wall, hence tended to distort a lot under the higher heat of brass.

  • What makes you think that you can’t braze cro-mo or mild steel to stainless or stainless to stainless with brass?

    I don't even know really!

    Maybe it's because the fluxes you'd use with silver mention joining dissimilar metals and maybe brass fluxes don't or the ones I've used haven't so I've just assumed that dissimilar metals needed silver.

    I do stainless (and other non ferrous metal) headtube badges and details and have always used silver but I guess that's also because it's capillary brazing to a certain degree.

  • You might be able to braze stainless with brass/bronze and it might be fine for racks but I wouldn't braze frame tubes with it and especially not Reynolds. Reynolds stainless suffers from intercrystaline cracking even at silver brazing temps. The tubes literally crack whilst being brazed. It's a well known problem with 921, to a lesser degree 953. I imagine it would be nearly impossible at the much higher temp needed for brass.

  • I am not seeing failures of brass brazed stainless frames. Given that silver braze is perfectly within the temperature range to cause intergranular corrosion on stainless tubing, I think coating the joints is the best option. No corrosion = no problems.

  • Right but not 921. Reynolds specifically say not to do this.
    I'm not talking about failures after riding. I'm talking about the tubes literally cracking during brazing.

  • My Reynolds stainless frames are 953. I tend to avoid the cheapjack options.

  • 953 is no longer available and hasn't been for some time.

  • A pity. I liked it, until some started coming apart.

  • Was that at the seam?

  • At joints.

  • I am looking to source a set of Columbus Gilco (or similar) tubing for my next project.

    If you have a set, or have knowledge of where I might source one, please let me know.

  • Anyone got, or know where I could get, a USA BMX bottom bracket shell?

    51.5mm/2.02" id.

  • ALL GONE!

    Any appetite in this thread for various fork blades and some chainstays before I put them on the framebuilding FB page? I haven't made any forks for years, and doubt I ever will now, it's a shame as I really like the 531 blades, I also doubt I'll ever use straight chainstays again.

    6 of Reynolds 531 (I think) raked fork blades (oval top)
    2 of some kind of raked fork blade (round top)
    2 of straight fork blades (round top)
    1 of 1"steerer brazed into a track crown (round ports)
    4 of straight chainstays round end (I think Deda)
    4 of straight chainstays oval end (I think Deda)
    1 of plain 1" steerer.

    They all have surface rust, but I reckon they'll be reet with a rub down.
    Not really sure how to price, would a fiver a pair be fair? Would be great to send as a bunch too so would be happy to offer a price for the lot.

    I'm in Sheffield and happy to post.


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  • I have a single speed bike, steel frameset that take regular wheels with bolt-in 100m front and 130mm back (track rear dropouts) and have V-brake posts.
    Toying with the idea of handing it to a framebuilder to have it converted to TA (12x100 front and 12x142 back), and disc brakes (post mount).

    The fork has a unusual design, so should be either pretty straightforward or not possible to do at all, so let's leave it on the side for now).
    What I struggle with figuring out is the rear end ; I would probably ask to replace the whole rear triangle to improve tyre clearance and convert to through axle, but it is the method for single speed chain tension that I have a hard time figuring out.
    For me, there are the following choices:

    • rocker dropouts, although almost not considerable because I need the brake caliper to be outside rear triangle above seatsay to avoid heel catch when pedalling (rear end is very short) even if it would be me preferred aesthetic design, unless there is a rocker dropout with caliper placement outside the rear triangle?
    • sliding dropouts, which would be the best option probably for the caliper placement outside the rear triangle, but I like a bit less the aesthetic compared to rocker dropout
    • fixed rear dropout (e.g. like syntace x-12 for example), placed at exact chainstay length for magic gear with the ratio I am using, with a potential derailleur hanger to add a tensioner if magic gear doesn't work, but seems like the less clever solution if magic gear doesn't work out and I would very much like to have no tensioner aesthetically

    Not a fan of EBB as a solution, I don't see any other one.
    I think the most reasonable would be sliding dropouts, even if not my first aesthetical choice.
    Any opinions on this?
    Edit: of course cost is also a factor, the lower the better as usual

  • The problem with sliding dropouts is that you have the aluminium sliding portion that is around 7mm thick and then you have the steel portion that it slides in that is a similar thickness, this will make the area around the rear axle even wider, if heel rub is an issue for you, any of these double thickness dropouts are going to cause a heel clearance problem for you, especially on a short chainstay.

  • That’s a good point, that’s something I will check on my frameset today to see how much « room » I have

  • Ok frame building types-a question. I am taking my old Gillott frame do Varhona this week as it needs a new drop out. However, the drive side crank is stuck fast, (and hence the axle etc is still in the frame I cannot shift it at all without totally bolloxing up the crank.) Is Winston going t0 be able to braze on a rear dropout with all this still in situ, or do I really have to get it removed in order for him to do the work? Frame is 531, if that makes any difference.

    Cheers

  • well this didnt go well... Granted the B&Q website states this is for copper only...

    @M_V, and all the other rack building pros, can you recommend a tube bender that will bend 10mm stainless (8mm ID)?

    Many thanks


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  • That’s the kind of bender I use for 10mm tubing.

    It’s usually the other handle that breaks for me.

    My current one is bolted to a big bit of brass square bar so I can hold it in the vice.

    You definitely got to help the tubing around a bit.

  • fixed it, then broke it even more...

    Maybe I need to build the @Hulsroy version!


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  • Get something that isn't cast but made from machined steel

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I am a frame builder AMA

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