Grant's Featherbed Special

guest76 · Oct 5, 2015

After a few different attempts, this is what I came up with

guest76 · Oct 5, 2015

I went for something more angular first, but when we made a prototype out of wood, it just didn't look right.

This curvier one, I felt much better accentuated the curve of the rear frame loop - my favorite part of the bike!

guest76 · Oct 5, 2015

So with the shape set, I set about working out what the dimensions should be based on those I had taken from the original swinging arm.

I came up with this

guest76 · Oct 5, 2015

Then we made a prototype out of wood, so we could try it on the bike, and see what it looked like

guest76 · Oct 5, 2015

I wanted to use modern suspension on the rear, to match my front setup, and really like the Öhlins shocks http://www.ohlins.com

Since I was building a Special now, i could get away with the piggyback canisters, which are infinitely more adjustable than the integrated units

guest76 · Oct 5, 2015

These units are from a Harley, but the internals (shim stacks) have been rebuilt to account for a bike that weighs significantly less, and a rider that weighs half that of what the Harley units were originally designed around.

The springs were also swapped out for lighter ones (the springs may need tweaking further)

guest76 · Oct 5, 2015

So with the shocks built up, I could trial fit my wooden swinging arm

guest76 · Oct 5, 2015

In fact, I got a bit carried away, and buttoned up the rear wheel too

This is a WM4 18" Excel shouldered rim with 8 gauge stainless spokes built by Buchanan's http://www.buchananspokes.com

The rear tyre is a Bridgestone BT45 which is 120/90 in size

cNw turned the hub to remove the ribs - i think this is a really nice touch, and makes it a little bit different!

guest76 · Oct 5, 2015

Here is the rear end with the wheel fitted.

It's exactly the look I was going for, and the measurements worked out perfectly!

guest76 · Oct 5, 2015

So armed with a working prototype, piles of dimensioned drawings and a head full of ideas, i needed to find someone who could turn my wooden vision into metal.

guest76 · Oct 5, 2015

After many calls, emails and discussions, i found a little engineering company here in England that felt brave enough to work with me.

We worked together, and eventually came up with this tweaked design

guest76 · Oct 5, 2015

Here is the swinging arm after the first bit of machining

guest76 · Oct 5, 2015

You'll see there are no holes are fittings yet

guest76 · Oct 5, 2015

Next up, it is mounted to the milling machine so that the slots for the adjusters can be made

guest76 · Oct 5, 2015

Here is a close-up of the slots

guest76 · Oct 5, 2015

Basically, i didn't want any big adjusting bolts sticking out the back!

guest76 · Oct 5, 2015

Then we could set about the shock mounts

guest76 · Oct 5, 2015

We went through a few different iterations of this, but we agreed on something simple and flowing in the end

guest76 · Oct 5, 2015

I went for a Manx style bushing rather than the standard Metalastic bushing

guest76 · Oct 5, 2015

There is no distance piece between the bushings on these, although I can shim it out to stop the swinging arm from nipping up solid, if for whatever reason I get my measurements wrong.

Grant's Featherbed Special

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