Tandem page 2

p0000038.jpg (click for 1792 x 1200 JPG, about 330k) is another view of the intermediate shaft bits: the front changer is mounted on a bit of old handlebar. The two pulleys for the front chain run are also not entirely as planned: I miscalculated where the bottom of the front seat would go, by about 5mm. But the way the chain runs, I had to deflect it quite a way with the pulleys. The pulley supports are pretty beefy, because the tension side of the chain goes through quite a sharp angle.I've supported both pulleys from a 10mm hi-tensile bolt so that seat movement isn't affected.
The frame separates just in front of the intermediate drive support block: there's a 40x3mm length of square-section inside, spaced out to be a snug fit with aluminium pads rivetted on. Four bolts each end secure it all together, and these bolts have also been handy for things like pulleys, cable stops etc. I'll probably use them for adding luggage capacity soon, too.

p0000039.jpg (click for 1792 x 1200 JPG, about 330k) shows how the front chain runs go, finding their way past track rods etc. Also shows the handlebars, made from a pair of MTB riser bars, with a cut-in-half straight bar for the end-pieces. They had to be strong enough for people to use them to help get in and out.

The steering was worked out with my Ackermann program, and it's turned out well. p0000041 and p0000042 (click for 1792 x 1200 JPGs, about 330k) show the extreme lock left and right: the tandem turns almost on the spot! It also handles fine. More by luck than judgement, at extreme lock the track rods hit the brake caliper mounts, which stops the wheels 'flopping round' further. The bump stops on the handlebar hit the cross beam at the same time, stopping further movement.

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