Hi Mark!
SJS Cycles indicate the Sun rims have wear indicators, but they are not visible to me in the product photos shown on this page:
http://www.sjscycles.co.uk/page/find/?name=sun%20rhyno&page=1 That's most likely because SJS Cycles didn'tphotograph the section where the indicator is located. It does not run fully 'round the rim as others do. More on that in a moment.
So far as I recall, early Sun Rhyno rims had no visible wear indicators. The later ones I've seen were pretty subtle an only visible in one place. Again, as I recall, they are a small stamped or machined circle near a sticker on the rim center...and that sticker can peel and fall off. I have Sun CR18 rims on my tandem, and those (polished silver) are pretty soft and easily scarred by the odd popped rock hitting them. I've seen some truly gruesome damage inflicted on other's Sun rims using steel tire levers. I always use plastic tire levers on my rims (prefer the VAR tire jack on narrower tires) and have thus managed to avoid this sort of damage myself. A side note, re: the wear indicator...given how soft the rims are, I wouldn't expect the indicator to be present a terribly long time.
The problem with wear-away indicators is not everyone thinks to check their rims regularly, and when they do, it is hard to tell if the rim is either too old to have had an indicator from the start, or of it has worn away. For this reason, I either caliper my older rims periodically to check for undue wear, or prefer rims that wear through to an obvious indicator, like the reinforced C-section in the Rigida Andra's extrusion cross-section.
Hope this helps,
Dan.
