I'm upgrading an old bike with a five speed dérailleur system which I'm trying to convert to use a three speed gearhub from Shimano. I have assembled the wheel, I know how to set up the gearhub itself, but there's one question that bothers me: the chain.
Currently, the dérailleur pulls the chain and keeps it in tension. When I install the gearhub wheel, the dérailleur itself is ought to go away, but as I understand I need to keep the chain tight. Should I make it shorter or install another pulley? Is it possible to somehow reconfigure the dérailleur to pull the chain as a temporary solution until I do it properly?