Meanwhile, back at the trike: After the morning coffee and rolls ritual I made a 2mm thick brass disk to replace the 4mm thick central spacer between the Trykit 2WD pawls. The original is alloy but I had no round stock handy in alloy in 1"/25mm diameter.
Even with half the bearing seals removed the wheels still would not spin freely up on the stand. Hence the thinner spacer to reduce end loading on the axle bearings. A 2mm spacer still ensures a positive 0.75mm interference. The 4mm disk applied 2.25mm difference compared with the gap between the inner ends of the bare axles.
While I had the rear end apart I stripped the Ultegra 10SP cassette and gave it a good clean in spray on, car engine cleaner. Once it had been all been given a good brush with cleaner it all came up nicely with a rub over with clean rags. I stripped and cleaned the Stronglight triple chainset while I was at it. No point in fitting a new chain on filthy components. Then there were the for and aft gear changers to clean thoroughly.
I rebuilt the cassette using 9sp spacers to see if this will help the indexing. Though I had to file the projecting tabs from the spacers before the sprockets would sit flat. There are no tabs on the 10sp spacers.
The Trykit 2WD free-hub will take an enormously wide cassette if needed. Easily room for 11 speeds. So there was still lots of room left with 10 speeds even with the extra wide spacers. 4 x 0.3mm = 1.2mm extra width. So not much to worry about there.
The Ultegra 10sp cassette uses a carrier for the three largest sprockets so I has no control over their spacing. The two smallest sprockets are also fixed in their spacing by the built-in metal rings. So I needed only 4 x 9sp spacers.
Once everything was clean, greased and rebuilt and the new chain fitted, the rear wheels spun for ages! A good result! I could tell the difference instantly just by pushing the wheels around by hand. The difference in freedom is really quite amazing. It used to be quite difficult to spin the rear wheels up to high speed on the big chainwheel by hand. I doubt there will be any problem with security of axle location or safety with reduced end loading on the circlips. The central spacer applies a mutual load on the ends of the axles during cornering.
Time for a test ride to the shops! While it certainly felt more free running my legs were tired from yesterday's jaunt. Again, the freewheeling effect could be purely psychological. Though I was easily able to roll uphill across the supermarket car parks without pedalling. Despite a side wind and load of shopping I was cruising at 20mph coming home. The indexing seems better though I have yet to fine tune the cable adjustment. I also forgot to adjust the stop screws on the rear changer for the widened cassette. Only 10 miles.