Whereabouts will you be? I was there six weeks ago down in the south west and found that Rad International would hire me a fairly decent Canyon Spectral quite cheaply. When I brought it back I met their MTB guide (all the others were roadies – summer is out of season for Mallorca biking) said if he’d known in advance he’d have taken me out for a ride, so it’s worth getting in touch if you’re down in Peguera or thereabouts. There’s a new trail centre above the town – it isn’t signed yet but it’s all rideable. I did a lot of pushing up and trying not to die on the way back down!
Make sure you get the brakes swapped around – the trails are steep, rocky and loose so you will be needing them!