Take the Train to Thun, then the bus number 1 from Thun Trainstation to Steffisburg Flühli. Get off at the station Marktgasse.
Or be sporty and walk from Thun Trainstation to Kunsteisbahn (Ice Rink) Grabengut: 15 min (1.1 km).
Check out the connections here:
Fairtiq – The easiest public transport ticket across Switzerland
You can find enough parking opportunities for your bike next to the Ice Rink.
Signalisation from exit Thun-Nord - Direction Steffisburg/Thun A6 - Car park City Nord Grabenstrasse.
Kunsteisbahn Grabengut, Kyburgstrasse 8, 3600 Thun.
Koordinaten: 46.76197, 7.62645