hornet if you are going for a solid machined plastic one get a peaice of nyloil , oilon or nylatron gsm these are all self lubricating . if you are going to use one with a bearing i would use nylon 66 and machine a small recess for the chain to sit into . if you go for a skate board wheel make sure its made from tdi polyurethane so i would go to a specialist skate supplier for this as the stuff on ebay is normally low grade urethane . sorry to go on but its the only thing i can give advice on and actually know what i am talking about.
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