I have been using Muc-Off for cleaning all my mountain and road bikes quite happily for the last few years. I spray it on my bike. Leave it there for 5 mins. Brush it in well and then hose her down. Voila - clean mountain bike. Seems to work. I used to use washing up liquid which messes up your bike and don't do the job well as plates, cutlery, pots and pans and bikes are different things you see.

some more useful blurb from manufacturer..

- All over Bike Cleaner, which cuts through grime

   while protecting your bike's finish

- Will not harm seals or disc brake pads. Spray on, 

   wash off, no sweat

- Fully biodegradable, alkaline based

- Safe on carbon fibre, paintwork, anodising, 

   aluminium, titanium, rubber, plastic, seals and 

   disc brake pads

- California Air Regulatory Board Compliant.

It's safe on anodising, paintwork, chrome, carbon fibre, suspension seals, rubber, disc brake pads and more importantly to the user too! It cuts through dirt, oil and grime quickly. Also has a 5 & 25 Ltr Re-fills. 

Some Technology

So why is Muc-Off with Nano Tech better?

In the past, bike cleaners have been formulated using 'Micro Scale' materials which are approximatelly 1/80th the size of a human hair. Muc-Off Nano Tech cleaner is formulated using 'Nano Scale' materials which are approximatelly 1/8000th of the diameter of a human hair. This dramatic reduction in material scale allows the Muc-Off formula to penetrate far deeper into dirt, oil and grime and gently break it down on an atomic and molecular level. The dirt is then rinsed away easily and safely with water, leaving behind corrosion inhibitors for future protection.

A painted or metal surface may look smooth to the naked eye but under a microscope it's full of peaks and troughs. Nano sized particles are able to fill these microscopic areas and bond to form a smooth protective layer that makes it harder for dirt to adhere to the surface next time you ride.