"How long do you ride the bike for?"

"How long do you ride the bike for?"
 

Let's say someone makes the habit of riding a bicycle every afternoon for fun or exercise, and I want to ask them "Normally how long do you ride for?"

Can I say it like this:
"Por cuanto tiempo montas la bicicleta?"

or is there a better, more accepted way?

Durante cuanto tiempo montas en bici?