Bicycle Mechanics - How to fix the Phantom shift!

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View Full Version : How to fix the Phantom shift!

RunJumpHop
08-19-07, 04:09 PM
Hey guys, I am riding a recently built up late 80's Vitus 979. It is originally a 6 spd with Shimano 600 components, but I have recently put on a new set of Bontrager Race wheels that I assumed couldn't take the old 6 spd freewheel (right?). So, I now have an 8 spd cassette but the same old shimano 600 shifters and derailleurs. I am running the shifters in friction mode and I am able to switch from gear to gear fine. BUT, when I get out of the saddle and really pump hard or climb a hill the bike will shift into a higher gear, which can be problematic obviously when climbing a hill.

Is this simply because the Vitus is so 'flexy' and puts tension on the cables when I really push it? Or is it my 8 spd cassette not interacting well with my 6 spd components? how can I alleviate this?

Thanks.

mike
08-19-07, 04:57 PM
Friction shifters?

If yes, tighten the friction cups via the bolt at the side of the levers.
melville
08-19-07, 10:06 PM
Look in your other three threads about this neat old bike.

1. make sure the cable is lubricated where it runs through the housing in back

2. crank the friction adjustment down (on SIS shifters, done with a screwdriver)

3. get some 8S downtube shifters

4. get some Simplex Retrofriction shifters like the Europros used in the 80s

5. friction bar-end shifters are another good cure

6. 8S index bar-end shifters are another fix (but then you'd be copying ME!)

7. STI, but you may have front derailleur and brake compatibility issues

Good luck

Mel