Halfords bike degreaser,`cos its safe on plastic,metals and rubber.Costs £5 for a big spray and it don't stink out your house/shed/garage etc.Plus you can put the can in your kit bag and use it on site.
If u are gonna use after market products only use water base degreasers.
I just give it a DAMN GOOD SCRUBBING with a soft towel then reoil the beauty/s -"The labour of love" i call it,others call it perversion.