Got my first hydraulic disc brakes on my new MTB and they are really something. As my workplace is on summer shutdown I have been riding lately and today was my last full free day so I went to ride Summer Lightning despite p***sing rain. Terrain here is sandy and puddles were *deeeeep* great fun, but wet sand everywhere and from the grinding noise on way home, either the Tardis is materialising behind me or the front pad mech and / or disc is a bit filthy. Stopping produces ghastly screeching like on a car with filthy wheels so methinks the disc and / or pads are somewhat mucky. On my hybrid (rim brakes) a bit of water and / or with cleaner does the job, any reason why that shouldn't be done with discs? Sorry if it's a silly question but I'm only a year back on any bike!