Just a quick recommendation having bought both 7- and 8-speed versions from various eBay sellers; the steel HG-type cassettes made by Sunrace are a good Shimano substitute, being of clever design/construction and seemingly lighter than the Shimano originals. They're built in a similar way to SRAM PG850 road cassettes with lots of material cut away and lightening holes aplenty, but with a more attractive price tag than SRAM. My latest acquisition is here:http://www.ebay.co.uk/itm/SUNRACE-8-SPE ... 3ccecad24c
As an aside, 12-25 is a useful range for cyclo-cross, although this particular one is actually going on my road bike.
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