Shimano SL-MY20 Disassembly / Modification
10-12-23, 06:20 AM
#1
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Shimano SL-MY20 Disassembly / Modification
I'm hoping to modify a Shimano SL-MY20 right shifter, to increase the shifting range to an 8 speed (friction).
Has anyone attempted to disassemble one, and/or modify similarly?
From the manual, and by looking at the shifter, it looks like the only way to disassemble one is from the top? But there's a nice little note in the manual stating "never disassemble!"
Cheers
Has anyone attempted to disassemble one, and/or modify similarly?
From the manual, and by looking at the shifter, it looks like the only way to disassemble one is from the top? But there's a nice little note in the manual stating "never disassemble!"
Cheers
10-12-23, 06:45 AM
#2
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Assuming that you're doing this after having checked that the shifter won't pull across an entire (wider) freehub?
If so, you can accomplish the same thing much easier by putting some cable liner on the section of cable that contacts the shifter body. That will increase pull and should do the trick.
If so, you can accomplish the same thing much easier by putting some cable liner on the section of cable that contacts the shifter body. That will increase pull and should do the trick.
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10-12-23, 07:45 AM
#3
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I haven't checked that, but good point. The shifter is a 6 speed, so the increase is minimal. I've seen in other thumb disassembly's that it's possible to increase the rotation.
I don't think there's the possibility to put some cable liner against the shifter body, due to the design, but I may misunderstand you
I don't think there's the possibility to put some cable liner against the shifter body, due to the design, but I may misunderstand you
03-17-24, 03:09 PM
#4
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Update on the modification. I'm really into these old shifters, big fan of the aesthetic, and hard to find a modern alternative.
If anyone else is interested, there's two issues that prevent the shifter lever rotating far enough around for anything over a 6 speed. The bracket underneath the shifter has a little tab which stops further rotation by design. The shape of the cable feed also prevents further rotation.
The tab is easy enough to grind off. For the cable feed I scanned this piece and modeled the modification in Rhino, then 3D printed it. If anyone else is interested in this mod, I'm happy to share the Rhino file. It now rotates around perfectly for an 8 speed.
If anyone else is interested, there's two issues that prevent the shifter lever rotating far enough around for anything over a 6 speed. The bracket underneath the shifter has a little tab which stops further rotation by design. The shape of the cable feed also prevents further rotation.
The tab is easy enough to grind off. For the cable feed I scanned this piece and modeled the modification in Rhino, then 3D printed it. If anyone else is interested in this mod, I'm happy to share the Rhino file. It now rotates around perfectly for an 8 speed.
03-17-24, 03:47 PM
#5
Must be symmetrical
Too bad it required so much modification to pull across 8 speeds. Other Shimano 6 and 7 speed shifters I've tried have worked.
eg I use 6 speed xt m730 shifters and Dura Ace 7400 6 speed shifters on a few bikes and both pull across 8, no issue. Deore II MT62 7 speeds work just fine too on 8, and they have a similar removable cover to the ones you have
If you want something that works without such extensive mods, these have worked for me.
eg I use 6 speed xt m730 shifters and Dura Ace 7400 6 speed shifters on a few bikes and both pull across 8, no issue. Deore II MT62 7 speeds work just fine too on 8, and they have a similar removable cover to the ones you have
If you want something that works without such extensive mods, these have worked for me.
03-18-24, 02:45 AM
#6
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Yea I looked into these shifters, both are just horrifically expensive compared to the MY20. The NOS one I picked up was £20, compared to £70+ second hand m730 or MT62
03-18-24, 02:54 AM
#7
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used to have those on my MBK Rockfighter back when I was 14 used to be fragile, I then upgraded to XT 739 shifters, this was a different story
03-18-24, 07:26 AM
#8
Must be symmetrical
I know shipping, customs and taxes are all going up on orders to UK from continental Europe, but this might be worth it. It is NOS, 7 speed, so will almost certainly do 8 in friction without modification.
https://www.ebay.de/itm/296128784535...mis&media=COPY
https://www.ebay.de/itm/296128784535...mis&media=COPY
03-18-24, 02:11 PM
#9
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It feels pretty solid! Won't be doing anything too extreme in my mid 30's now haha
