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8-speed STI shifter/cogs compatible w/ 6-speed 600 rr derlr?(6 posts)

8-speed STI shifter/cogs compatible w/ 6-speed 600 rr derlr?killermustard
Dec 2, 2002 11:22 PM
I'v just picked up a used Sora STI 8-speed triple gruppo and a 15-year old Specialized Allez 12-speed racer(didn't even know Specialized was around back then), which I want to mate into either a 16- or 24-speed. The Specialized has the full Shimano 600 gruppo; I believe the original parts (e.g. derailers and cranks) are lighter and better quality, so I'd like to keep as much of them as possible.

I do realize that I may need a new BB and chain.

My questions:

To make a 16-speed, can I keep the (1) front 600 derailer, (2) rear 600 derailer, and (3) the 600 double crankset, and install just the STI shifters with an 8-speed cogset? If not, what old parts can I keep?

The Sora front derailer is a braze-on, and the bike now uses a clamp-on. Do they make adapters so that I can install the Sora front?

Thanks all.
re: 8-speed STI shifter/cogs compatible w/ 6-speed 600 rr derlr?killermustard
Dec 2, 2002 11:26 PM
Addendum:

Sorry, my question about keeping the front 600 derailer was meant to address it's compatibility with the alternative of a triple chainring setup. Will it work?

Thanks all.
re: 8-speed STI shifter/cogs compatible w/ 6-speed 600 rr derlr?Rusty Coggs
Dec 3, 2002 5:31 AM
Sora 8 front speed shifters are double or triple chainring specific.You have to determine what your are and stick with it.
re: 8-speed STI shifter/cogs compatible w/ 6-speed 600 rr derlr?Andy M-S
Dec 3, 2002 3:11 AM
You face some interesting problems. If you decide to stick with the double, the front derailer will probably be fine. The current crankset will be fine. The FD is a risk because Shimano indexs front AND rear, and if the derailer doesn't move right with the amount of cable the shifter pulls, you're not going to be pleased.

Same problem in back--it's unlikely that the 6-speed 600 stuff is indexing. If it isn't, chances that you'll get decent shifting in back are quite small. Even if it is, I doubt that Shimano kept the same RD geometry when they went to 8-speed, but it's possible.

I'd install the new shifters and new RD to start, and see how things go. If you want to go triple, you'll need a new FD, clamp-on style (105 is available and fairly cheap), as well as the appropriate BB for your Sora crank.
re: 8-speed STI shifter/cogs compatible w/ 6-speed 600 rr derlr?Rusty Coggs
Dec 3, 2002 5:28 AM
The front derailer will unlkely work with either a double or triple.It needs to be STI compatible,meaning the arm the cable attaches to needs to be perpindicular to the derailer cage.The rear derailer will work if the original shift system was index. The crankset is ok.
rear derailleur may work.rufus
Dec 4, 2002 5:41 PM
if it's able to shift across the full 8 cogs in the rear. you'll need a new freehub body as well, as the 8/9 speed are a bit wider than 6 and 7 speed bodies.