Thanks for the information.

I don't know what is included in the ultralight kit, to allow the use of the Ethirtheen cassette, it should include at least a new XD or XDR freewheel for the rear hub or a complete new rear wheel ?

Could you post a picture of your Helix with the adjustments made for your size ?

I have tried Tubolito's (in ETRTO406 on my Moulton) and its the inner tube with which I had the biggest amount of flat tires I ever experienced with a bicycle ! For the Tubolito special patch, it seems they have now a new kit with a special glue instead of self adhesive patches.