this is what I use on the bike. I wash it on really hot days and leave the bike in the sun for about 1/2 hour ... never bother with towel drying ... bike is always completely spot free.and this is only 20 bucks
except chlorine and other TDS (total dissolved solids) which contribute greatly to water spots.If you live in an area without a water treatment plant it may be a an idea to consider. Water Treatment plants are usually looking to put out water with a rating of less than 0.30 NTU. You will not see anything in that water.