Depends on the frame it's going into. If it isn't a singlespeed frame he'll need something just to get the chain "adjusted" correctly. I wasn't talking about shifting, just getting the chain tension correct between the HS and the rear cog. A singlespeed frame will need to have slotted dropouts or sliders. Can't see an EBB working very well with IGS tabs. Or whatever they're called.pewpewpew said:im pretty sure the hammerschmidt doesn't introduce any extra slack when shifting. Its all done via planetary gears so the size of the cog that's turning inside the system doesnt change. therefore, an old rear derailleur wouldn't be necessary.