BUY the kirkland signatue roller bag. the soft sided kevlar one is only sold on costco.com (not in stores--which sell a lesser quality, smaller version with 4 spinner wheels) It fits in every sizer I have tried, and we have logged over 150k miles on 16 airlines worldwide in the 8 months since we got this new model. Extremely well built, comes with a bag of spare zipper pulls, and the 2 wheels are replacable using an allen wrenh (wheels are standard rollerblade size).

This new model is advertised as 21.5 and it is almost exactly 'true to size"

The ones sold more than 12-18 months ago were sold as 22" but oversized and as noted above don't fit in all the sizers. We had used one of those for 7 years and over 1500 flights before the handle rail broke. We emailed costco just asking where we could have it repaired, and they had us bring it to any store for a full refund Store gave us an immediate refund (and it's pretty easy to find a costco, with stores in many countries.