I use the Salsa Air IATA cabin spinner for travel on QF and CX all the time. But these airlines specify the usual maximum linear dimensions for hand luggage, rather than stating a maximum length dimension. Having said that, IIRC it's only a whisker over 21 anyway. I have never been asked to check it and I have never had trouble with storing it in the overhead bin (except it won't go in wheels first into the side overhead bins on a 767, but almost nothing does). It's lightweight but doesn't feel fragile and I've never felt concerned putting it into the overhead. My main caution with this design is the single pole telescoping handle, which is clearly a trade-off for reduced weight but makes stacking a second bag on top quite a challenge.