Muc-off Bike Cleaner Concentrate 1 Litre $23.65 + Delivery ($0 with Prime & $49 Spend) @ Amazon UK via Amazon AU

Great deal for those MTBers out there. I even use this to clean my car rims.

ECO-FRIENDLY: Developed to allow you to re-use and refill your 1 Litre spray bottle, 500ml of Bike Cleaner Concentrate uses 89% less packaging than the equivalent two bottles of Nano Tech Bike or Motorcycle Cleaner.
GO FURTHER, GO HARDER: 500ml of Concentrate will give you 2 Litres of our award-winning pink bike wash – just add water.
NANO TECHNOLOGY: It’s our infamous state-of-the-art Nano Tech formula in concentrated form, so you get the same deep cleaning power that attacks dirt on a microscopic level.
BIODEGRADABLE: Fully biodegradable, alkaline-based formula that is free from acids, solvents and CFCs so that you can clean guilt-free.
SUITABLE FOR ALL BIKES: Whether you prefer pedal power or something with a little more oomph, the Bike Cleaner Concentrate is suitable for use on all bicycles and motorcycles and is safe to use on all parts and componentry.
Included components: 1 x bottle nano tech bike cleaner concentrate gel