I had read the tourist information about Spetses being car-free, except for six taxis. This did not prepare me for the reality. There are more than a few cars on Spetses, and there are more than a few thousand motorbikes, quad bikes and motor scooters. Together they make for an unpleasant environment. There are almost no footpaths, so dodging traffic is a constant challenge for any pedestrian. Traffic jams were not uncommon on narrow roads, not designed to deal with the realities of Spetses in 2014.
The hotel manager seemed surprised when I said that I found the island over-run with traffic. She insisted that motorbikes were not allowed on the roads accept mornings and afternoons. Clearly, she was relying on her own car for transport, and had not tried to walk five minutes down the road for many years.
If you are happy to hire a motorbike yourself, then all will be well. If not, think again. Spetses may not be the right place for you. certainly, I regretted having to stay there because I like walking and that is a no-no on Spetses.