Problem with a thumb shifter on a miyata mtn. bike
10-14-20, 09:44 PM
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Problem with a thumb shifter on a miyata mtn. bike
I have an old Miyata Valley Runner Mtn. bike I'm having trouble with the thumb shifter
to the rear derailleur. It shifts but has a lot more clicks than the 6 cogs on the rear derailleur.
The derailleur is a Shimano SIS but I'm not sure of the shifter. Here's a couple photos of
the shifter
to the rear derailleur. It shifts but has a lot more clicks than the 6 cogs on the rear derailleur.
The derailleur is a Shimano SIS but I'm not sure of the shifter. Here's a couple photos of
the shifter
10-14-20, 10:17 PM
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The shifter is a "friction" shifter. It does not index on any particular cog- just shift until the chain is on the correct cog then nudge the shifter until it stops making noise.
This is how old farts like myself learned to shift. It works fine with a little practice.
This is how old farts like myself learned to shift. It works fine with a little practice.
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10-14-20, 10:29 PM
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The shifter is a "friction" shifter. It does not index on any particular cog- just shift until the chain is on the correct cog then nudge the shifter until it stops making noise.
This is how old farts like myself learned to shift. It works fine with a little practice.
This is how old farts like myself learned to shift. It works fine with a little practice.
10-15-20, 01:41 AM
#4
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For a detailed explanation you can reference this thread: https://www.bikeforums.net/classic-v...d-shifter.html
10-15-20, 01:56 AM
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There are no indexed derailleurs (except positron?). The indexing happens at the shifter. There are only index compatible derailleurs. Means they have a compatible pull ratio to a particular indexed shifter.
10-15-20, 06:42 AM
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Some friction shifters have a ratchet mechanism to reduce effort when moving the lever. SunTour "Power" shifters and Shimano "Light Action" shifters, for example.
10-15-20, 06:54 AM
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The bike may have originally been spec'ed with friction shifters and derailleurs. The derailleur may have subsequently been replaced.
Some friction shifters have a ratchet mechanism to reduce effort when moving the lever. SunTour "Power" shifters and Shimano "Light Action" shifters, for example.
Some friction shifters have a ratchet mechanism to reduce effort when moving the lever. SunTour "Power" shifters and Shimano "Light Action" shifters, for example.
10-15-20, 07:02 AM
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If you're certain the derailleur is original, then perhaps a previous owner replaced the indexed shift lever with a friction one because the indexed shifter failed. I see this fairly often when indexed grip-shifters fail, for example. Does the other lever match?
10-15-20, 07:19 AM
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Both levers match but I can't find any markings of brand. I can't find in the bikes specs what shifter it came with, just the derailleur
10-15-20, 02:14 PM
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Another reason to change the index shifter to a friction is some people find it hard to deal with twist type shifters and the friction-thumb type is just easier for them to operate.
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10-15-20, 09:26 PM
#11
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The bike may have originally been spec'ed with friction shifters and derailleurs. The derailleur may have subsequently been replaced.
Some friction shifters have a ratchet mechanism to reduce effort when moving the lever. SunTour "Power" shifters and Shimano "Light Action" shifters, for example.
Some friction shifters have a ratchet mechanism to reduce effort when moving the lever. SunTour "Power" shifters and Shimano "Light Action" shifters, for example.
Still puzzles me why those were called light action though since the levers are quite stiff IMO. They take so much effort to press I actually dislocated my left thumb one time while shifting. Popped right back in place but holy heck did that hurt.
10-16-20, 08:06 AM
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Friction shifters don't get speed designations. I know some Shimano SIS thumb shifters could be toggled between friction mode and indexed mode, but the friction mode was pure friction, no ratchet.
10-16-20, 11:29 AM
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Deetox There is a common error when routing front derailleur cables to the front derailleur that causes excessive cable tension and, by extension, excessive force at the lever.
