slack chain problems

k3vinjam3s Posts: 266
edited April 2013 in Workshop
Just changes the cassette and chain on my bike and seem to be having a problem with the chain seeming really slack. I replaced a 105 12-27 cassette with a 11-28. I counted the links at 106 on the old chain and set the new chain at 108 links as the cassette is slightly bigger. Is this too many links? What would be the right ammount of links for this cassette with a compact chainring?