I'm adjusting the derailleurs on my Raleigh Airlite 100 Racer. It's got a two speed crankset on the front and 7 speed freewheel on the back. I've looked at Park Tools, and I've done every thing they've said. It's rides near-perfectly on the bottom 3 gears and the top 4. However, if I use the big ring on the front, and fourth sprocket up on the rear (or anything above), the chain grinds loudly against the outer cage plate on the front derailleur. This is not a light, barely noticeable grind, it is clearly there as it is very loud. I've tried fiddling with the indexing and the L limit screw, but it hasn't helped. Tried searching around for tips as well, but found nothing. Anyone know a way to sort this? Thanks.