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Shimano Mega 9 shifters?

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Shimano Mega 9 shifters?

Old 07-10-22, 09:18 AM
Road Fan
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Shimano Mega 9 shifters?

Mrs. Road Fan’s grocery bike, only now being pressed into service, is a 2003 Breezer Liberty, a pretty well-equipped straight bar road bike - some racks, some panniers, some 700c “urban tires, aluminum frame, Vbrakes, full fenders, Basta wheel dyno and B&M lights, and now with a B72 saddle. Hubs and derailleurs are Deore, the chainset and shifters are Shimano Mega-9.

Gearing is 3x9 roughly 22-42 in front and 12-32 in the rear. These gearing details are approximate because I haven’t counted them out for quit a while. The Mega-9 have little gear indicators, and a thumb lever to work against the springs and a finger lever to step it the other way. Front derailleur is bottom pull.

Problems: The front and rear derailleurs move properly in response to the triggers, but the shifter detects need a lot of travel before they will stick at the “new” detent. It’’s far enough that sometimes she can’t get the shift she wants without contorting her hand - unladylike!

So I think the shifters should be overhauled, if possible to clean out gummy crud that may be getting in the way of the little parts and springs.

Has anyone done this on the Mega-9’s? Any worries beyond dropping little parts into the carpet? Any instructions or rebuild kits out there?

Or do I just need new parts? The front and rear mechs are in fine shape!
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Old 07-10-22, 09:57 AM
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It sounds like the barrel adjuster needs to be turned a "few clicks" to effectively lengthen the cable housing.
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Old 07-10-22, 10:50 AM
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The left thumb on the Mega-9s I have uses a lot of travel to get its shift, and there's not much you can do about that, except maybe angle it so it's easier. The right one uses only a little travel for one shift, but can accommodate two or three positions/shifts, depending on how far you push it. Maybe stick to one-at-a-time there.
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Old 07-10-22, 12:38 PM
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Agree with Bill Kapaun. Start with the cabling before anything else.
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Old 07-10-22, 04:44 PM
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If it is the distance of the throw and not a difficulty pushing the lever, what you have is what you have.

Cleaning might make it easier to push, but all the shifter does is pull cable. The pawl catches and everything stays there until you push it again or pull the trigger to release the pawl.

You can dink around with stops or cable adjustment all you want, but that lever will need to swing a certain amount to engage the pawl.


Edit added: In theory, you could reduce the lever length and the distance would be less, but the amount of thumb pressure would increase due to less leverage… literally.
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Old 07-11-22, 07:09 AM
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Cleaning 20+ year-old shifters isn't a bad idea, but don't do it over carpet. This is one place WD-40 works well. Since they still operate, you won't need to flush them, but they'll still take a generous spray and will drip. Stand by with a rag, and put a pan on the ground/floor. Remove the cable installation access plug and squirt there. You might get a cleaner, crisper shift.
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Old 07-14-22, 07:50 PM
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Originally Posted by andrewclaus View Post
Cleaning 20+ year-old shifters isn't a bad idea, but don't do it over carpet. This is one place WD-40 works well.
I did this with the trigger shifters on my 20+ year-old mountain bike with low/middle-level Shimano components. I flushed them with "normal" WD-40, then lubricated them with another WD-40 product I found: spray white lithium grease. The shifters work like new.
However, the distance the levers have to be moved to engage the pawls remains the same.
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