SS MTB Build - Part 4

SS MTB Build - Part 4

Next, it was time to finish mitering the chainstays and seatstays and drill vent holes in the BB and seattube before tacking and brazing the frame up. One thing I didn't take photos of was how I capped the tops of the seat stays. For this I basically just used some offcuts from the toptube to create scallops that I brazed on, filed to shape and mitered to the seat tube.

Finally time for some heat. I started tacking and brazing the seat tube to the BB. Then mounted it back up in the fixture to ensure it was all square and that the miters for the rest frame still fit nicely. Being that I brazed the seattube all the way around I ended up adjusting the miter on the downtube so it fit the ST/BB fillet nicely. 
Once I got the fit right I was able to tack up and braze the front triangle. Leading up to this build I worked on getting my brazing speed up while still achieving a good internal fillet. While putting heat to the actual frame I did my best to be quick and I was definitely working faster and laying down better fillets than when brazing up the previous frame, but there's still room for improvement. Once the front triangle was brazed up it was pretty quick work to get the rear triangle pieces tacked on and brazed up as well.

Finally all the main bits of the frame were attached together into one unit. After a soak (in our bathtub since I don't yet have a suitable soak tank) to get the flux off I got to work cleaning up some of the fillets.
For this frame I opted to keep the fillets mostly raw, as this is a prototype/experiment and I felt that spending many extra hours on filing and sanding fillets would be an unnecessary time waster this time around. Therefore I just removed some burnt flux and wire brushed the fillets and linished the tubes to clean them up.

The last thing I had to do before applying the gun blueing finish was to solder on the guides for the brake lines. I know that this should normally be done before brazing the frame, but waiting until now was a conscious decision for this build as I lacked the experience of having built other MTB frames to 'know' beforehand how I wanted to do the routing for the brake line.

SS MTB Build - Part 3

SS MTB Build - Part 3

For this build I didn't want to use the bottle boss reinforcement 'diamonds' that are available from most framebuilding suppliers. I wanted to create something a bit more unique and personal while taking the chance to experiment some more with my letter punches and silver soldering.

My idea was to cut out a strip of bronze plate, stamp it, drill it and braze it on as the tube reinforcement for the bottle bosses. After hand cutting and shaping the plate I drilled the bottle boss holes and measured out where to stamp the letters. The plate on the DT reads "EGRESS" and the one on the ST is stamped with the frame serial number.

Once stamped, I used my wooden tube blocks and a tube offcut to press it in the vice to give it a curved shape to match the tube it was to be soldered onto. This was my first time using type U flux and silver to solder bronze onto steel, so heat control and silver flow was not spot on, so it's not perfect but I still like it.

 

 

SS MTB Build - Part 2

SS MTB Build - Part 2

The seat clamp lug I bought with the tubeset needed a bit of work. Opted for this one as it's got a lot of material to work with. Sharp points and love heart cutouts is not really the style I'm going for, so it needed a bit of customisation.

Hand drew a shape that I liked better with a sharpie straight on the lug. After a little hacksaw and file action the lug is looking a lot better.

The original seat clamp lug. 

The original seat clamp lug. 

Hand carved.  

Hand carved.  

I also did some experimentation with letter punches. Punched in "EGRESS" vertically along the back of the lug. I then laid some bronze filler over the letters and sanded back the bronze to reveal the letters. Got a nice and smooth finish and the bronze letters should pop a lot more once I've blued the steel. 

Punched

Punched

Filled & sanded

Filled & sanded

SS MTB Build - Part 1

SS MTB Build - Part 1

After a bunch of planning and many hours in front of the computer figuring out the specs for the frame, and making some necessary bits for the jig, it's finally time to start cutting, filing and joining metal.  

Day one consisted of making all the necessary adjustments to the jig, prepping tubes by marking out butting and where to cut etc. 

When I was just about to start mitering the seat tube I discovered my first mistake - I had forgotten to take into account that the seat tube was externally butted at the bottom, and thus had a bigger diameter. Meaning that my mitering templates that I had painstakingly prepared needed to be adjusted and re-printed. Oh well, that was a minor thing to get wrong. Back to the computer to make the necessary changes and update the cutting templates. 

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With new templates for the seattube and the downtube I got started with the cutting. Always measuring multiple times before cutting or making any irreversible changes to the tubes. The seattube got mitered up to the bottom bracket first. Then downtube to BB. 

 BB/ST/DT junction. Nice and tight.

 BB/ST/DT junction. Nice and tight.

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The most challenging part was to miter the downtube to the tapered headtube. I am happy with the resulting miter and I think I got it really tight. Not much room for error since the other end of the downtube was already mitered to the BB. 

At the end of day one I had mitered up all the tubes for the front triangle. Slow progress, but I rather get things right than work too fast. 

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Bike Check

This is a bike check for my first hand built BMX frame. The bike has been assembled with parts from my previous bike.

The frame was built with a True Temper SuperTherm tubeset from S&M Bikes originally used in their BTM frame. I built the frame entirely by hand with a fillet brazed construction and the geometry is based on the numbers I have concluded are ideal for my preferences and style of riding.

Build list:

  • Frame: Egress Bikes ‘Nameless’ (21” Prototype)
    TT 21” | HT 74.5 | ST 71 | CS 13.78” | BB 11.77”
     
  • Fork: Proper Bike Co
  • Bars: T1 Classic, 8.85”
  • Grips: Cult x Vans
  • Stem: Haro Lineage (Topload)
  • Headset: Fly Bikes
     
  • Cranks: Fly Bikes, 175mm
  • Sprocket: Nightfall Bike Co. | Killuminati, 29t
  • Chain: Odyssey | Key Chain
  • Pedals: Fly Bikes | Ruben (plastic)
  • BB: BSD | Mid, 22mm
     
  • Hubs: Tree Bike Co
  • Rims: GSport | Birdcage
  • Spokes: Phil Wood
  • Nipples: Pillar, alloy
  • Tyres: Fit Bike Co | FAF 2.25” & 2.3”

Weight: TBC (Frame weight: 2.3kg / 5.07lbs)

Next Build

Hopefully in the next couple of weeks I'll start frame #3.. 

My first mountainbike was a Specialized Crave SL - a rigid singlespeed MTB. This bike shaped my view of what a mountainbike should be - pure and simple fun. After having owned a couple of 150-160mm travel enduro bikes, the singlespeed is still my go-to bike for when I want to race XC or go for longer rides at my local trails. 

So this is a project I'm really excited about - I'm building myself a new singlespeed hardtail!

For this version of the bike I'm recycling the carbon fork off my Crave SL, but all the rest of the components are going to be brand new. All these parts have already been acquired and are currently sitting stashed away, just waiting to be put to use. 

I'm quite looking forward to the end result. 

The frame:

The frame will be constructed from Columbus Zona tubing and be equipped with sliding dropouts. Being that it's the first time I'm building an MTB frame, this will be very much a prototype and I'm fully expecting that changes will be made for future versions. The geometry is going to be a little bit more relaxed than an XC specific race machine, but the aim is for the bike to still be responsive enough to hold its own on fast technical singletrack.

I'll post more updates as the build progresses. In the meantime, here's a render of what the bike might look like when finished.