wondering

I've been wondering about speed skate bearing spacers today. Like these: 

• http://www.trurev.com/product_images/w/137/spacers__42812_zoom.jpg

I was outside looking through the bucket of wheels and zip bags of bolts, washers, spacers and other various hardware I've collected just in case I might need it. My goal was to set up three sets of wheels with bearings and spacers so I could do relatively quick swaps to see how they felt in comparison as best I could.