Which derailleur for 7 speed?

[Teamfixed]

Hi all
This is on an 87 Raleigh Randonneur. I've just changed the 6speed block to 7 (the dizzy heights of 1989 now) it went in fine with the addition of a washer on the drive side to space it a little. I have put SIS dt shifters on which came from a 7sp Galaxy recently so I know they work.
Thing is the original derailleur, a Sachs Huret, isn't liking the index increments so I guess the pull ratio is wrong for this? Will an 8speed derailleur work for this or was 7sp distinct?
Many thanks

 

[Cycleops]

The Sachs would have been used with a friction shifter I think ? So maybe try it with one of those.

 

[Teamfixed]

Yes it did have a friction ratchet shifter. However I am intending to use the 7speed indexed shifters that i have. Much nicer to use!

 

[TheDoctor]

A Sachs Huret mech wasn't designed to index over 7 speeds.
It probably wasn't designed to index at all!
You need a Shimano rear mech, and pretty much any 7/8/9 speed mech should work. Just make sure it's from a decent supplier. I've bought a few rear mechs off Ebay recently, and they've been poorly-made rubbish. Something like Acera should do nicely

 

[Teamfixed]

Thanks @TheDoctor that's great. Ordered.

 

[Teamfixed]

All done works a treat

With these 7sp indexed levers. How very modern😁

 

[raggydoll]

 

[raggydoll]

From what I can see of it, looks like a cool bike.
I love old school shifters like that.
Looks like you have a good range of gears now too!

 

[Teamfixed]

 

[Teamfixed]

It's a beauty 😊

 

[raggydoll]

Oh come on!
That is one classy bike!

Are the wheels 27 1 1/4 or 700c?

 

[Teamfixed]

700
Probably one of the first for the type of bike.
It's as good as new mechanically and with 28mm gator skins a lovely compromise.

 

[raggydoll]

I'm jealous!

 

[Gillstay]

Nice!