If you take your mountain bike to Juneau, you can go all 10 miles (or is it more?)north/south on The Road, but if you want to go east/west you may have to carry it up and down the stairs Juneau uses instead of sidewalks.
It's a lovely town full of colorful wooden houses and Russian artifacts mixed in with new state buildings [SOB, Spam Can], two miles long and three blocks wide. Bald eagles circle over downtown in the heat-vent thermals. The whole burg is glued to the side of Mt. Juneau and the glacier, and you can meet a bear on the stairs. April is likely the sunniest month, and the folk festival is wonderful. I've gone a number of years myself, tho not recently.
The weather in spring in Southeast (what the people of the area call the panhandle part of Alaska) is not that different from Seattle, and the wild rugged land and is beautiful. Try it, you'll like it.
Blessings,
Barbara