"Do you know how to ride a bicycle?"

Translation: Umíš jezdit na kole?

[learninggerman]

"Umis jak jezdit na kole?" is it wrong?

[kacenka9]

Yes. The JAK is not needed and not wanted in there. It could be used if you used VÍŠ but even then it is not very nice czech. Yet people say it as VÍŠ JAK... in other sentences is a proper. Víš jak se dělá chleba? Do you know how to make bread?