DArthurBrown

I have a 1985 Centurion Sport DLX that I'm considering modernizing for my wife. I've procured most of the necessary parts to do so, but am still unsure about the rear spacing and derailleur.

Rear dropout spacing is 126 mm. I'll have an LBS check to see if this can be spread safely to 130. I think it will be.

The problem is that this model bike did not come with a derailleur hanger built into the frame. This was from the era of Suntour including the hanger as an integral part of the derailleur. What's more is that I had to replace the derailleur last year with a Shimano Tourney (it actually works flawlessly as it is) because these are the only derailleurs that come with the hanger included. So... two questions...

1) Will a Shimano Tourney rear derailleur accommodate a 9-speed chain well?
2) Will a Shimano Tourney rear derailleur have enough travel to swing through all nine gears?

The other option is that I could get a generic derailleur hanger and afix a Sora or Alivio rear derailleur, but this gets remarkably expensive and makes it more appealing to simply get my wife a new bike.

DArthurBrown

No one?

meb

1) Unlikely, the chain is much narrower than the teeth the wheel was designed to run on.
Maybe you could take the wheels of a 9 speed rder to create a 9 speed compatible claw in the Tourney-but that is likely approaching the hanger approach in expense.
Mounting a 9 speed frame mounted rder to the hanger would give results are likely to be more predictably favorable and you could go with a smoother shifter rder. The Tourney likely would work on an 8 speed if 8 is an acceptable compromise.
2) Should be no problem, the 8/9/10 speed derailleur throw is only about 4 mm more than the 7 speed, the Tourney should handle that.

That frame is likely chromoly so should be no problem spreading it, but there were aluminum Diamondbacks so verify it with a magnet. If it's aluminum, don't do it.

Dan Burkhart 

An adaptor claw like this
https://i43.tinypic.com/e99ld2.jpg
is available anywhere, and will allow mounting of any direct mount derailleur.

bikeman715

I agree with Dan Burkhart , these adaptor claw are available anywhere & are cheap, and with it you can use any dérailleur you wish with it.

DArthurBrown

Just an update on this old thread. I had an occasion to test a Shimano Tourney derailleur, an old Acera derailleur, and a newer Altus derailleur with a modern 9 speed drivetrain using bar-end shifters. None of the derailleurs were beyond 8-speed. The old Acera was from an era when 7 speeds was the maximum available.

Not only did every combination of derailleur-drivetrain work perfectly once adjusted, the chain seemed to fall more squarely on the old 5-8 speed triple chainrings that I was using than on many modern 9-speed cranks I've tried.

Sheldon Brown commented on this. Paraphrasing: Older derailleurs of a similar brand work perfectly with shifters of that brand since the cable throw and derailleur swing is usually standardized and backwards-compatible.

Retro Grouch 

What are you using for a shifter?

In addition to the issue of respacing the frame to 130 mm, I'm wondering about the closer cog spacing of the 9-speed cassette. It's something that I've never tried but I'm wondering if the Tourney derailleur is going to be precise enough to index reliably.

operator

It will.

It's the shifter that determins the spacing anyways. Too bad I wasn't around to correct post #2. It is 100% incorrect. The I.D of a 9 speed chain is the same as a 7 speed or 8 speed chain which is 3/32.

DArthurBrown

The frame was a Trek 620 that was already spaced for 130. The total travel of the Tourney was completely compatible with a what's needed for a 9-10 speed setup. It actually had some travel left over, so my guess is that it would work for 135 spacing as well.

The Tourney was perfectly precise, the only reason I didn't end up using it was because the other derailleurs I had looked better, but they all worked just fine.

The shifters were Dura-Ace 7700 bar-end shifters (9-speed). The indexing worked perfectly between the Tourney and the shifters. No issues whatsoever.

DMF 

That would have been my guess had I seen this article when it was current. No surprise, and glad it works for you.

Btw, spacing isn't relevant to the derailleur function. Sprocket stack height is. Spacing is only accidentally (in the Aristotelian sense) affected by stack height.