I live in Zurich and don't to Ironman... but a few thoughts. Triathalon is huge in Zurich, there are quite a few tri clubs here (only websites I found were in German). I imagine Basel would be similar and there will be tons of support for triathaletes.


Swimming - there are lots of good public pools in Ch so don't that will be a problem, my colleauge even participates in a twice a week 6:30 am morning training swim with alot of triathaletes. he is a swimmer not an ironman.

Cycling - it is never too cold to train outside, just get the proper gear. I cycle all winter on the weekends (when I am not skiing). There are definitely spin type classes, my gym has 1.5 hour one every Monday which is geared towards cyclist/triathaletes.

Now, this is Zurich but Basel must be similar.