Hello,

I wonder whether anyone can help diagnose the shifting problems I'm having with a Dawes Super Galaxy, c. late '80s-early 90s. I've been trying to get the derailer correctly adjusted, and the indexed shifting works in the highest (smallest) sprocket, as well as up to the 2nd and 3rd highest sprocket. There are only five speeds. The next shift, however, is consistently rough, and basically requires I shift past the first click, then back again, and it's the same going to the lowest (biggest) sprocket, sluggish and imprecise.
The 105 downtube shifter has six clicks, plus a kind of no-man's-land after the click furthest down (meaning, pulling the shifter back towards myself as I'm riding), and it works fine in friction shifting mode.
I'm just wondering why some indexed shifts work fine, and others are off, as I thought barrel adjustment should normally get them all aligned together.
Would this be because the shifter is mismatched, and made for 6-speed with tighter spacing?
What I'd like to achieve is a wider gear range, as the 5-speed is pretty narrow, and more precise indexed shifting. I know part of this is probably to do with the old freewheel sprockets, with non-ramped teeth. Can I upgrade to a newer, improved 6 or 7-speed freewheel?
The dropouts measure just over 120mm between them.
I can post photos if that would help.

Thanks very much. The last pieces of advice from here were extremely useful and got me through the muddle I was in regarding changing to a rigid fork on the other bike.