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I have an old road bike, that I converted to a hybrid bike, I just use it for small tourings. Some time ago I changed the handlebar, the brake levers and the tires.

Recently the derailleur broke up, it was in bad shape and there's no way to repair it, so I just want to get a new one, also I would like to replace the shifters, as they are the old ones that are on the frame, and put triggers like an MTB.

The bike has a 6 speed cassette, I was thinking in a cheap Shimano Tourney derailleur but I can't happen to find trigger shifters of 6 speed on online stores. My idea would be to put a 7 speed shifter with just 6 speeds and someday change the cassette.

What you think? Would be possible to put a 7 speed cassette? Any other suggestions?

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3 Answers 3

It's best to have chain, shifters that match your cassette, both in terms of number of speeds and make (and to a lesser extent model).

In a non-matching configuration, your chain will try to sit slightly between gears in certain settings, which is actually rather annoying.

Having said that, what you propose will work for locomotion, and depending on how much annoyance you're cool with bearing in a given day it may work well enough for your desires.

I tell you these things as someone who has piecemeal upgraged from 7 to 9 speeds; it isn't an ideal solution.

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Depending on the age of your bike the derailleur may or may not fit. Most forward facing rear drops from the 80's and 90's used a small bolt to position the derailleur and the axle nut to secure it in place. More modern bikes mount the derailleur with a separate piece of hardware to a separate deraileur hanger. The Tourney appears to use a separate hanger. Doing some on line research it seems the tourney is offered in both types of mounts. The TX 35 mounts for the forward faced drops. The TX 55 mounts for a derailleur hanger.

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Good point. Yes, it's from 80's or even older, I should ask my father. And yes, I forgot to comment it, the hanger is part of the frame, so no modern derailleur hanger. I will check it before buying it. –  hellyeah Jul 20 '12 at 11:40
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There's no problem with having a shifter with more "speeds" than the derailer/cluster, so long as the pitch between the components is the same. The shifter will simply stop shifting when it hits the limit. (Generally speaking you probably want the "dead" gear to be the highest one.)

(Just did some digging on Sheldon's site. 6-speed clusters come in 5.0, 5.3, and 5.5 spacing. Pretty much all 7-speed clusters are 5.0. But essentially zero 6-speed clusters are designed for indexed shifting, whereas virtually all 7-speed clusters are designed for indexed shifting. This means that 7-speed (indexed) shifters would would not down-shift (to a larger sprocket) a 6-speed cluster very well. You need friction shifters.)

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