new rear derailleur for old school 80s road bike.

30yroldclunker

Über Member
Location
Okinawa
So 80s era road bike. I recently changed both 8 speed rear cassette (now 11-32) and added a smaller front chainring (now 38-52). My derailleur is Shimano 105 from that era, I have down tube friction shifters. The derailleur is a short cage (SS in Shimano terms) and I want to change to a medium cge (GS) to accomodate the new drivetrain capacity.
Would a modern 105 like this
https://www.wiggle.co.uk/shimano-105-r7000-11-speed-rear-derailleur/
which is rated for 11 speed cause problems with my set up bearing in mind my cassette is 8 speed and chain is a HG40
https://www.wiggle.co.uk/shimano-hg40-6-78-speed-chain/
or would it be safer to go for the 9 speed rated Sora derailleur?
https://www.wiggle.co.uk/shimano-sora-r3000-9-speed-rear-derailleur/
I guess what I'm trying to work out is whether the new 11 speed rated derailleur cage is narrower than my original cage and would cause issues.
 

carlosfandangus

Über Member
Just checked mine, the new 105 has a 10 mm cage, so does the Sora one!
 

si_c

Veteran
Location
Wirral
Should be fine if you are using friction shifting, make sure you get the GS rather than SS derailleur. The alternative would be to search ebay for a Shimano long cage derailleur that is period correct - something line an 300lx derailleur should work fine.
 
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