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Old 05-11-12, 01:46 PM   #1
zastol
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Mixing front shifting parts.

Having some trouble with front shifting.

I'm building up a road bike from old stuff I have around.

My rather unique setup:
Newest model Shimano 105 front derailleur.
1990s Shimano RSX 8x2 "brifters".
Shimano 600 "arabesque" crankset for 5-6 speed chain. 1970-1980s?

I just cannot get this to work, I get chainrub on outer and inner side, lever just does not have enough throw?
Is it really so that 5-6 speed chainrings/crankset do not fit the 7-8 speed levers/derailleur/chain setup?

I need to get the front shifting to work cheaply and good enough to race! I'm really close to pulling the trigger on a new 11speed Campa group even though I really can't afford it!
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Old 05-11-12, 02:01 PM   #2
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STI has big kathunk shifts, no fine tuning, after the shift. their engineers
seem to sort out the cage shape so if you dont go out of the best
chain line combinations it wont drag much.

friction shifting FD allowed repositioning the FD cage after the shift.

so maybe you are using cross chain gears , IDK I cannot see a thing from here.

As chains had to get skinnier to get # 9 + cog in the space of 8,
then the chainrings had to get closer spaced, because the chain was thinner.

Planned obsolescence is a Plot.

Last edited by fietsbob; 05-11-12 at 02:04 PM.
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Old 05-11-12, 02:30 PM   #3
gyozadude
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Is there a potential to examine the pinch bolt position on the FD? Sometimes, clamping the cable closer to the pivot will generate more pivot at the expensive of more tension on the cable. But this can give you the extra 1-2 mm to move the FD cage so there is no rub.

I've been able to do this trick to get Suntour Cyclone FD and Shimano Sante and Shimano FD-6400 to all work with 2 spd front STI with older cranksets.
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Old 05-11-12, 02:34 PM   #4
zastol
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Yeah. I'm thinking the chainrings are spaced just too wide apart on the old cranks. I think I have some 600 cranks from the 90s that I could try on...
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Old 05-11-12, 02:36 PM   #5
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Quote:
Originally Posted by gyozadude View Post
Is there a potential to examine the pinch bolt position on the FD? Sometimes, clamping the cable closer to the pivot will generate more pivot at the expensive of more tension on the cable. But this can give you the extra 1-2 mm to move the FD cage so there is no rub.

I've been able to do this trick to get Suntour Cyclone FD and Shimano Sante and Shimano FD-6400 to all work with 2 spd front STI with older cranksets.
Oh, I have not thought of this, I'll check it out, thanks!
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Old 05-11-12, 02:38 PM   #6
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I have a 6-speed crank working just fine with a 9-speed rear and Microshift shifters (Shimano STI-compatible). The big difference is that I'm using an older (1985) front derailleur (Shimano 400, I believe?) that has a wider cage than the newer stuff. Plus, I don't sweat it if the big-big and small-small combo's have chain rub. That's true even on my 2010 10-speed road bike, if I don't use the half-clicks on the front. 6-7-8 speed are relatively compatible with each other (note that they sell 6-7-8 speed chains, but never 8-9 speed chains or 9-10 speed chains). I'd say you need an 8-speed front derailleur, and to not worry much about rattling in the cross chain combos- you shouldn't be there anyway.
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