Incredible to watch, how the years rush by. I started using the A-Bike 2009, a copy due to the price. Now, I am writing from my 7" Android Phone-Tab ... The A-Bike is for bicycles, as Linux, is for computer operating systems. You can get a A-Bike for 60 usd in China. Thinking about GPL software, the A-Bike is almost "GPF" hardware. (General Public Free

"It would be a nice task for Google; free internet, and a free A-Bike for everyone!"
Today I am using the 8" version with inflatable tires. Rubber tires never worked fine for me, vibration is also enormous. I think also due to the lax interface between metal an rubber. The pneumatic tire, is firmly fixed to the metal, due to the air pressure.
But yes, the 8" runs better than the 6", and the construction is better. The tire air pressure of the 8" is lower, almost half the pressure of the 6"; good! The main gear case is also stronger, but there are still some flaws.
Going to the point, I suggest to improve the clamps on the front and rear tubes.
The idea is to extend the upper side of the clamp, to press also the inner tube from the outside, instead of weakening with two cuts, that critical part, that is the top of the outer aluminium tube, to create the aluminium clamp.
Inside the clamp extension there could be two o'rings to press against the inner tube.
This clamp could be used, in the front and rear telescope tube arrays.
Regards
Cris from Chile
Also, on the last picture, you can see the solution I am using for long time now, on the rear telescope tube, worked fine with the 6", and now with the 8" version.