To be honest, I'd rather ride without it. But then, I'd prefer not to bother with a helmet, high viz clothing, bike clips etc. It is not so much restrictive, but it does get hot, damp and smelly! It's actually worse in the winter (condensation?), especially as runny noses are more prevalent at that time of year! The trick is to wash the filter regularly (I do mine weekly) and to replace it every so often. Sounds yukky doesn't it? It can be, but I think that's preferable to being ill with asthma. Bet you are glad you asked!?:)) I should say, I only use the mask when riding in cities. When cycling in the countryside or by the sea, I don't bother. Fortunately, for me, the need isn't there on those occasions.