Gavr's Oops! What was I thinking? Thread. Finished...

Yes that was my problem!

Decided to have a bash at tapping BB shell myself, Cyclus tool on order
 
Getting excited now, first real bits and pieces beginning to trickle in.

First off I've coldset the rear triangle to 120 mm using the Sheldon Brown method and a long piece of 2 x 4 to take the SRAM Automatix 2 speed autoshifting hub with coaster brake! Tweak the dropout alignment with a big Bahco adjustable so pretty well parallel.

I've measured up the hub for spokes, planning 2 cross onto Sun CX-18, 36 hole black rims 20 x 1 3/8 i.e. 451. More when the rims arrive from the States...

I also have a chainset - 50 tooth Sugino RD2 with 165 mm cranks and a stem, a snazzy Nitto Technomic at 270mm so longer the the old stem and sorted for seatpost clamp a smart black Thomson 31.8mm.

Now a choice - what does the front end look like a Town bike with the Velo Orange Left Bank or something like the EA50 Monkey Bar...
 

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C'mon then Gav spill the beans on the SRAM Automatix hub, how does that work? (I don't mean the mechanics just the idea)

You have got some real cracking parts there it is sure to be an ace build. Lovely.

Regarding the colour well thats your choice, it has got to be the hardest choice when completely refurbing a bike.

I'd stick with the Monkey Bar, the swept back bars look cool but the Twenties have short reach already (at least mine has) so bringing the bars even closer could have you looking like Graham Obree with your hands tucked under your shoulders....(not that look like Mr Obree could ever be considered a bad thing!!)
 
I think drop bars is quite a good look on these personally

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The SRAM hub starts you in a low gear and once the hub is spinning at a fixed rpm clicks up into a higher gear automatically. The set point is determined by the strength of a spring resisting the centrifugal force on a pawl inside the hub - a bit like an old freewheel mechanism. The shift point can by adjusted by opening up the hub and playing with the spring, which I may have to do with a small wheel or it will shift a too low a speed. Braking is by back pedaling. Weight is about 1 kg so significantly less then a SA. It's SRAM's re-working of the old German Sachs hubs who they took over some years ago. I'll open it up when I've got a big cone spanner. I didn't have to file the rear drop out just coldset to 120 mm from 113 mm


The idea here is that it will make a really clean build with no gear or rear brake cable to worry about so I simply need a front brake.
 
Time for another update, the frame is off at the paintshop, so attention turns to wheels.

20 inch x 1 3/8 inch (451) rims in 36h drilling are tough to come by. SJS does some 28h but I couldn't get the 28h SRAM hub and already gone with the 36h version.

So all the way from sunny Florida a pair of Sun-Ringle CR-18 rims - I could only find black. Almost perfect except for the muppet in customs who cut open the box for a nose around and resealed it with his metal knife inside, leaving a couple of small dings! Nothing too bad though.

For those who are interested, some measurements. The SRAM hub is just about symmetrical so well designed for a strong wheel. Hub diameters I make 68.5mm and the centre to flange about 25.5 mm. The rim ERD measures 441 mm as given in the catalogue. I had heard that these can be a bit variable so all good there. Weight is about 400g so pretty strong and light.

Small spokes are also a bit scarce, again SJS has a good range of British made stainless spokes, which stand out from the iffy stuff sold as BMX spokes, but for the back wheel I wanted a familiar brand. Decided on 196 mm Sapim Leader 2 mm plain guage for a 2x build, as I certainly couldn't find any butted spokes in this length. I went with 2x cross as I was concerned that the spoke angles entering the nipples might be too extreme given the large flange hub and the 36 h drillings.

Ready to build up...
 

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So I spent a bit of time wheel building this morning. Lacing was a bit fiddly given the weight of the hub but all went well. In to the stand and a nice tight build. They really feel bombproof. Pinging at the same tone all round and de-stressed. Added a band tape and ready to go. The whole thing weighs in at fraction under 2 kg. With most of the weight at the hub it should feel fast.

The front is going to be built on a shiny Hope Pro III Mono but I'm waiting for spokes. These require something a bit longer than used in BMX wheels about 208 mm and that's just where there's a frustrating hole in most suppliers' catalogues. In the end I went with the SJS stainless spokes, remains to be seen what they're like - that's a job for the weekend.
 

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