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Shimano Nexus Inter 4 Shifter

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chuzz

'Lil Knee Scuffer
I'm not sure if this is where I need to post, but figure a mod can move it if needed. I was gifted an Esquire Nexus bicycle recently. Last week, I decided to put new tires on it as the ones on it were dry rotted. After getting the tires on it and the wheels back on, it wouldn't shift. I only have one gear and am not sure which one it is. This bike has a Shiman push button shifter with a lever under it. The hub is an SG-4R31. All I can figure is the lever under the shifter changes the hub gear and the push button shifter changes gears up. So, to upshift, you push the button and the gears get higher, to downshift, you hit the lever. I took the danged push button shifter apart and now I can't get it put back together correctly. Do any of you know of a site where I can find a schematic break down of how that shifter goes back together properly. I THOUGHT I had it right, but I still can't change gears on this bike. It's very nice bike and I love the way it rides, but I can't change gears and am peddling constantly to go anywhere. Please help me if you can. Thanks.
 
Thanks for the welcome and the link, jimbo53. I have searched Sheldon Brown's information and he's got a TON of info on the SG-4R31 hub assembly, but not a word about the shifter anywhere. I guess I'm screwed unless I can figure it out on my own. I hate when things come apart and something unexpectedly drops out. I need to start recording stuff when I disassemble them, I guess. I used to be able to figure things out, but since having survived 2 brain surgeries 15 years ago, my comprehensive abilities have abandoned me almost 100%. I don't recommend brain surgery unless it's like me and a matter of life or death.
 
You might want to check out Rat Rod Bikes forum, too. Lots of folks over there are doing amazing custom work and use Nexus multi-speed internal hubs. Maybe they can shed some light on your shifting issues
 
Thanks, man. I got rid of the 2 speed Schwinn. Tires were more than I wanted to spend on it. Dude that bought it didn't want the fenders or chain guard. Anyone want them? If I can't figure out this shifter after I look at Rat Rod Bikes, I may do some customizing of my own to it. I really like this Esquire and may just put a regular derailer and a different wheel on it along with new cables. I THINK I can figure out how to do that.
 
Don't know that shifter, but Shimano's integrated brake/shifters cannot be put back together to work properly without at least some mystery special tool (and maybe not at all). I had read that ahead of time, but figured the warning was for dummies. Turns out, I'm one, too. Figures, I would be the last to know.
 
I dunno, I don't really see any need for any specialty tools. The hub could use some snap ring pliers, but if you're good with a couple of small flat blade screwdrivers, that'll take care of the snap ring. If the warning is for dummies, count me in. Apparently I'm a dummy too!
 
I don't know if I can help or not, I have the SG-4C35 on my 48 Roadmaster, I do not know how close it is to the SG-4R31.

I am pretty sure the hub cartridge is the same, yours has a roller brake, mine is a coaster brake.

Either way, when you set and adjust the shifter or replace the cable, on the hub are two red lines, they are alignment points, they should be lined up when the hub is in 4th gear, then everything is downhill from there.

I believe the shifter that you are describing is the Shimano Nexus ST-4S20 shifter, if so, they don't make it anymore and it is kind of a unicorn to find.
http://www.bikevintageparts.com/index.php?route=product/product&product_id=75

If you check that link out, and it is what you have, then, at least you have the technical name for it to start your hunt with.

I would think though, that you could replace said shifter with the standard Nexus grip shift, which is what I have and they are readily available and easy to find.

Also, if you are describing it having a brake lever on the shifter, this Nexus Revo should work also.

https://www.thebikeshopstore.com/ca...MI-8mQmPjX4QIV3rfACh15igpzEAQYCCABEgKSGPD_BwE


Here is a couple photo's of the alignment points, in fourth gear.

57438169_369214977029237_2936558746177896448_n.jpg


57257008_2026437427659688_2530959476605845504_n.jpg


This is the standard Nexus 4 speed grip shift, rather simple to find.

57456964_340588649920730_5900726456962514944_n.jpg


This is what my hub looks like, really other than the coaster brake, pretty much the same beast.

57366650_2270470679663483_379395768588435456_n.jpg



The bike it is on.

27501128_10155421646322921_8714273492199230747_o.jpg





Hope it is somewhat of a help, let me know if I can be of any help.

Pierce
 
I tried Rat Rod Bikes, Jimbo, but can't get them to send me a confirmation email so I can join. I'm going to try again. And Pierce, thanks for the info, but my shifter isn't like those. I'm going to try to get my daughter to post some photos of what mine looks like later today. Neighbor has a moped with a loose wheel that he wants me to check out. I might make a couple of bucks off him, but suspect it's just a loose wheel bearing that needs adjusting. He just bought it and it sounds to me like it wasn't assembled correctly.
 
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