I have used Copenhagen for close to 30 years with no ill effects. I pretty much have one in at all times unless I am riding. When I rode motocross, I used to leave it in. On mellow Z2 rides, I’ll ride my bike with a fresh cope in. I don’t think it has any effect on my cycling or fitness…and even if it did…I’m not getting paid to ride. Some of the pro cyclists (especially from the Northern European countries) use a lot of Snus. I forget the name of the guy who even won the Giro D’Italia and would ride with a Snus in his lip. Read about that in Phil Gaimon’s book “Draft Animals”. Anyhow, I wouldn’t worry about it. Enjoy and ride on.