Construction begins

in my last post i said I had begin cutting the templates for the chain stays.  The original XR2 design calls for these to be made from aluminium, and while it's possible for me to do this, I had thought about making them out of carbon.  My thought was to make a plywood and balsa former that was to be wrapped in carbon.  But when i started cutting the wood, I realised what a nice bit of wood I had.  It's 6mm modeling plywood, birch I think.  So by way of an experiment I'm going to attempt a wooden swingarm.

I've deviated from the original design again...  The original XR2 has a chain wheel in the middle of the bike, so the right chainstay is set in behind the sprocket, and above the bottom bracket.  As I'm dispensing with this sprocket, I've made the chainstays symetrical.  As a result, I can make a jig and use it to form both sides.

In order to stop the rear wheel rotating and stopping the roller brake from working, I've recessed some lumps of metal into my chainstays.  The epoxy is curing on these just now.  The plan is to add a couple of layers of ply to the chainstays, then join them together in the middle to take the suspension pivot.  I'll be adding a few layers of varnish to lift the colour of the plywood.  This is an experiment, so I'll see how it goes.

Of course, now I have chainstay and frame templates made up, I had to make a mockup using the other components, clamps and imagination.  Ignore the headtube height and angle - that's the angle it wanted to wedge itself in at.

Re-Cycling

The other day I visited The Bike Station in Edinburgh.  It's a project that takes old bikes, refurbishes them and sells them on, with the surplus cash being used to support cycling initiatives.  As a result of thework they do, they have piles of old bike parts for the homebuilder to buy.  After being welcomed from one f the staff, he pointed me towards a wall of filing cabinets full of every part imaginable. 

I came away with handlebars, 2 stems, and a set of pedals, but I was still short of a 20" disc wheel and a head tube.  After speaking with a member of staff, I was taken up to the warehouse, where all the bikes that are being sorted live.  As luck would have it, when I went in,I spotted a 20" wheel with a disc hub.  It's not a great brand of wheel, but it runs true and the bearings are sound.  As for the head tube, I was hoping they would have a damaged frame that I could have taken an angle grinder to.  No such luck.  The only frame they had that could be considered an appropriate write off had an oversized head tube (1.5"?).  It looked like the former owner had cross threaded the bottom bracket shell and mangled the threads.  It was a shame, as it was an exceptionally light frame that was once a very good bike.

there were a couple of othr things  was after, but it was goingto be unlikely I would have found a headset and a bottom bracket.  These will either stay with the bikes to be recycled, or be in such a poor condition that they are not worth recycling.

I did see a trigger shifter for my Nexus hub,but it looked like it had been harvested for parts, so I decided against it. 

So for the bars, stems, pedals and wheel, I paid £15.  I woud have been a lot more on Ebay.  And I got a new bottom bracket from another bike shop for £20.  I was happy buying new, as I know this gets a lot of abuse.

I also visited Laid Back Bikes in Edinburgh to discuss chain and seat options.  While I'm planning on building the genuine XR2 seat, there was some nice upholstery on display that cuold be modified to fit my bike.  If comfort becomes an issue, then I may consider a change.  As for chain, I'm probably better just buying standard chain lengths and joining them with powerlinks.

On the construction front, I've started cutting templates for the chainstays.