「[自転車]{じてんしゃ}は[楽]{らく}だったです。」
This is ungrammatical. As a Japanese-speaker, I do know that a few of us would actually say it, but if one said or wrote it in school, it would certainly be corrected.
The correct sentence would be:
「自転車は楽でした。」 or
「自転車は楽だった。」
The former is a little politer than the latter.
Now, onto how to translate it..
To tell the truth, it is rather difficult without context. A very short sentence/phrase like this can mean a few different things without any context to go with it.
Without context, most native speakers would think of the following.
"The bicycle ride was comfortable."
"The bike felt comfortable."
"(Going there by) bicycle was easier (than doing so by other methods of transportation)."
It would not be taken to include the meaning of "used to" unless the context clearly suggested it. It would be taken to refer to the simple "near" past.