What are the bumpy parts around the spindle of some pedals? Does anybody know what the bumpy part near the threads of this pedal are for? They look like they might fit a special wrench, but I can't find any that would fit.



I feel like I must be missing something, and that I've seen these bumps around, but never understood their purpose.
The 'official' tool that engages with that bumpy collar is the Shimano TL-PD-40 bearing shaft removal tool. It's a plastic tool designed to be used with a larger wrench, or a vice. Here's a pic: 
TL-PD-40

If you're interested in servicing your pedals using this tool and others, here's a how-to from Park Tool: http://www.parktool.com/blog/repair-help/spd-pedal-overhaul