I got the recommendation to buy some electrolytes online at Wiggle, Evans or Chain Reaction. That won't be a problem.

But these pages are nice and I ask myself if I could import other bicycle parts (hubs, rims or wheels) without problems. I know I'll pay 7 % VAT on product + shipping but is there any customs duty on such parts? And if there isn't duty, will I pay duty because someone declares it wrong?

Anyone tried that?

I imported tools and electronic parts for CNC machines and that went all well, but never tried bicycle parts.

Bicycle parts are 10% plus the VAT. The duty paid is based on price of goods plus shipping, not the just the value of the goods.

Sometimes though you get lucky and you don't have to pay any duty or VAT, unless they use DHL or Fedex, then there's no escape :-)

yes I know: landed costs for the tax.

VAT from the landed costs+tax

on top maybe clearance fee.

that way 10% tax can be easily a total payment of 30%