dinkjs

So I was in a LBS alittle while ago and questioning about a 105 RD for my bike (it is a Nishiki Olympique 12)

And they stated that the Shimano 105's will only work on a 9 and 10 speed bikes only now (mine is a 6 speed in the rear) Now referencing this forum I have seen that rear derailleurs will work on any speed bicycle that the 10 spd info they put is just there for nothing. Can someone give me a clarification on this?

davidad

If your bike is indexed the 105 will work. It will always work with a friction shifter.

dinkjs

I have downtube shifters...so i have no idea about indexed or friction shifters

HillRider

You NEED A new bike shop. Yes, a 9 or even 10-speed version of the 105 RD will work fine on a 6-speed bike if you use a 7/8-speed chain, which is about all you can find these days wider than 9 or 10-speed chains.

desertdork

The "9/10 speed only" statement by the shop may have been made from the perspective of chain widths.

When comparing the cage widths of an "8-sp era" Shimano 600 RD and a modern Ultegra 6600 RD, I couldn't see a noticeable difference. Though I didn't run the 6600 RD with an 8-sp chain, I suspect it would have handled it with clearance to spare. If I understand correctly, 6-, 7- and 8-sp systems operate with chains of the same external width, and these chains are often sold as 6/7/8-sp compatible from retailers.

*Edit: Just saw HillRider's reply. So then the 6-sp chains (when they were available) were probably slightly wider than the replacements currently available.

HillRider

Yeah, years ago there were relatively wide 5-speed chains that also worked on "standard spaced" 6-speed freewheels. Sun Tour then introduced an Ultra-6 freewheel that allowed 6 cogs to fit into 5-speed width 120 mm dropouts but required a narrower chain. This narrow chain also worked on later 7-speed freewheels and cassettes and finally on 8-speed cassettes. So a current 8-speed chain is usually known as a 6/7/8-speed chain as it works with all of them.

Homebrew01

Indexed shifters means they "Click" into each gear as you shift, so you don't need to finesse the shifting. Early indexing was done with donwtube shifters, until integrated brake/shift levers came out. Before indexing, downtube shifters were "friction" meaning that the shift levers were kept in place by the friction of the bolt, and you had to find the correct gear yourself, sometimes overshifting & having to shift back a bit to get it just right.

With indexing, the shifters, rear derailleur & cassette need to be compatible so that with each "click", everything moves & lines up correctly as you shift from one gear to the next.

With "friction", your hand & ears adjust until it's quiet ..... noisy clattering means it's not quite in gear. You can mix & match a lot of different components because there's no precise indexing involved.

The late 1980s was when indexing started.

dedhed

I have a 9 spd 105 on my daughters 87 schwinn with light action 6 spd indexed shifters and it works just fine in index as well as friction.

dinkjs

Your awesome....yes then I have indexed downtube shifters

Pepper Grinder

There's no real point in putting a modern 105 RD on an older 6 sp drivetrain. Waste of $. You're better off snagging an older RD from ebay, or PM me and I'll dig you up an old school 105 RD from the parts bin.

dinkjs

Everyone has there own opinion or reasons for doing what they do Pepper Grinder

dedhed

I dunno, I bought a brand new RD5501 105 gs for $34 last month for my kids bike. My 10% off coupon even paid for the shipping. It was that or put the $34 new ultegra I bought last year on. Figured I'd keep that in stock for MY bikes. there's deals out there.

FastJake

Unless I missed it, OP never said how old his 105 RD was.

shelbyfv

You are probably satisfied now that the new rd will work, given the correct chain. If you have not already purchased the 105, I would suggest you look at the Sora. It is shiny silver and may look better with your vintage bike. Only about $30 and will work well.