Stainless Superlight

Stainless Superlight

Well this one has been a long time in the making! Back in 2014 I had been studying the various stainless steel alloy tubesets from Reynolds, Columbus and KVA. And also investigating the best rod and flux to use to join them. Stainless, although with similar properties in terms of strength and stiffness to cromoly, cannot be joined with brass fillets. It is best brazed with a silver based alloy – this is a low temperature process and generally silver is much more fluid than brass, which makes it harder to build a fillet at the joint. I was keen to build a prototype frame to test the tubing and process, and was planning to do so that summer for English frame number 100. I duly ordered some Reynolds 953 tubing, and some Fillet Pro rod and flux. But then I had my little run in with a tree and was on the couch for three months. Once I got back in the shop my priority was getting caught up with customer builds, so the stainless tubes got put on the shelf and sat there for over a year.

By the fall of 2015 I was close to being caught up, and also figuring out bikes to show at NAHBS – so it was time to resume the stainless project. The latest stainless alloys have some pretty impressive numbers for strength – which means some very thin (0.3mm) wall thicknesses, which potentially makes for a very light frame. But with that strength comes hardness, so working with the material is very hard on cutting tools. I think if I do much more work with this tubing I will need to figure out an abrasive mitring setup. For this first frame I just started with a fresh set of cutters – if I was careful I could get two cuts from each before they were done! Once all the tubes were mitred and prepped, I polished them, and then sent the downtube and headtube to have my logos laser engraved.

The brazing went well, small fillets to keep the weight down. There aren’t quite as many small parts made in stainless, so I had to machine my own seat binder, direct mount brake bosses and cable stops. The frame will have wireless eTap shifting eventually – for the show I put regular SRAM Red parts on there, so made a removable headtube sleeve to provide temporary cable stops.

When looking at the tubing specs, I figured I should be able to shoot for a frame weight right around 1kg. To check progress towards this goal, I actually weighed each tube before the final assembly. It was a little disappointing to discover that I would have hit that goal if it wasn’t for the chainstays! A set of S3 chainstays are almost 100g lighter. I spoke to Reynolds about this – they are aware of it, and working to improve their process. Knowing how hard the material is I can appreciate the difficulty of ovalising and tapering a tube whilst trying to control the wall thickness down to 0.5mm. Hopefully the weight gets lower in the future. In the meantime, having a few extra grams in the chainstays isn’t a bad place to have it.

With the frame done, it was time to look at the components for the complete bike. At NAHBS in 2012 I showed a 10.8lb bike. So I thought it would be cool for the show this year if I could figure out a way to get this one under 10lbs – with pedals, ready to ride. It is a lot of work to chase every gram, but a pretty fun project. I was very happy to do the final assembly and see 9.94lbs on the scale!

I haven’t had a chance to ride it yet – I’m waiting for the eTap parts to arrive, then I will put some regular wheels on and start clocking up some miles. Based on the material properties and the tubing sizes I used, it should ride very similarly to my other bikes, but I’ll report back on that in due course.

Full specs and weights listed below – scroll down for the gallery; thanks to Tina Buescher for the photos!

Frame: English custom stainless 1112g
Fork: Edge (Enve) 1.0 260g
Headset: KCNC Morion M3 38g
Wedge/topcap: Extralite Ultrastar 2 12g
Stem: Extralite Hyperstem 88g
Handlebars: AX Lightness 162g
Seatpost/saddle: Dash carbon custom 142g
BB: THM 74g
Cranks: THM Clavicula SE compact 304g
Chainrings: Fibrelyte carbon, 36/52 82g
Chainring bolts: KCNC 8g
Front wheel: Enve 1.25 rim, M5 hub, Ti spokes 316g
Rear wheel: Enve 1.25 rim, Extralite hub, Ti spokes 430g
Tires: Tufo Elite 272g
Skewers: Tune U20 22g
Cassette: Recon aluminium, 11-23 100g
Chain: YBN titanium 208g
Front derailleur: SRAM Red 22 72g
Rear derailleur: SRAM Red 22, custom pulleys 134g
Brakes: EE Cycleworks (direct mount rear) 180g
Shifters: SRAM Red 22 277g
Cables: Aican Bungarus/Powercordz 60g
Cable stops: Custom removable 25g
Pedals: M2 Racer Orb 98g
Bartape: Lizard Skins DSP 1.8 40g
TOTAL: 4520g (9.94lbs)

4 Comments

  1. cool-beautiful bike!!

    the saddle has some fore/aft adjustment, right? i think i’ve seen some pictures but not sure.

    the seat post is more than 27,2 mm, right?

    any downsides to those pedals? they look interesting..

    and 4520g (9.94lbs) for the whole bike.. WOOOW!!

    best regards,
    Mircea

    • Hi Mircea,

      Yes, the saddle has both fore-aft and angle adjustment.
      The seatpost is 27.2mm.
      Honestly I haven’t used the pedals; the bike will get Speedplays when I ride it.

      thanks, Rob.

  2. Hi,
    Beautiful bike!
    Why didn’t you use TIG welding for this frame?

    • Thanks Vladimir! Well I don’t have a TIG welder currently… Also, with the super thin tubes there is something to be said for the gentle radius of the fillet for having less of a stress riser at the joint.
      Rob.

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