We are casual bike riders, with a crossover street/light dirt trial bikes, for both of us.
I ended up not taking them with us to Alaska. We carry them on the back of our our CRV, when we do take them. I think we would have ridden them maybe twice not he whole trip. And for those times, we did not rent bikes, even though rentals were available.
Now kayak's are a different story. We do not have them, but did rent some canoes on lakes. (We're deciding between a tandem inflatable kayak, or inflatable canoe that also has a transom for a small motor. We'll purchase as our X-ass gift to each other... And it's a 50/50 choice at this time...).
Back to bikes. Unless you stay in say Fairbanks, Anchorage, Valdez, Haines, etc. for longer periods to time then is 'the norm' for Alaska RV trek's - you will not find many places to comfortably ride them.
But again, we're casual bike riders. For those of you that are avid bike riders - it would be like me without a good cabernet onboard... (I'm and avid wine enthusiastic, so this is natural to me...
Best to you, and do what is right for you