Try Andy at http://www.tramuntanatours.com/ he hires excellent mountain bikes (Trek Fuel and Remedy’s, plus some weird 29er stuff). There’s also apartment options through him, but no pool.
The riding is as good as other areas in southern Spain, but takes a bit of finding. But there’s easily a week’s worth around Soller without the need to use a car or van to transport bikes. You might not see another mtb’er in a week of riding, though it does seem to be catching on a bit.
You can get a route guide here
http://www.rockandride-mallorca.com/
It’s worth getting a copy, or asking Andy for advice, as rights of way are a big issue on the island, with most of it being private land.
Have fun!