Hello Robess 22
It doesn't work for me, the helmet has a very narrow shape, in summer without a cap no problem, in winter with a cap the pressure is too great and very uncomfortable to wear. I would advise you to go to a specialist shop and try it on! For me it was a bad purchase.

hey robess22
even if the cap is only 1mm thin, the circumference would increase by more than 6 mm. that would be almost 58 cm head circumference. so i would say no. the helmet would be too small. I can't answer how much tolerance the manufacturer has allowed for, because I'm not at the end of the helmet size range. my tip would be to choose the next larger model.