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Shimano SG-8R31 internal HUB

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Shimano SG-8R31 internal HUB

Old 12-20-19, 06:41 PM
  #1  
Edichek
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Shimano SG-8R31 internal HUB

I recently bought a Raleigh Cadent bike on ebay. The bike was equipped with Shimano SG-8R31 internal HUB. I soon noticed that there were problems with the HUB and brought it to my LBS. I paid to have the problem fixed, but the HUB continued to make all sorts of nasty noises and I'm afraid to ride it lest I make the matter worse. Eventually I decided that instead of spending more money on a sick HUB, I might as well buy a new part (Amazon sells them for about $110) and be done with it. Now, I also have Breezer Uptown 8 which, coincidentally, is also equipped with Shimano SG-8R31. However, upon further examination, I noticed that Breezer's hub was drilled for 36 spikes while Raleigh Cadent had 32. This got me thinking. I mean before I purchase a replacement part, shouldn't I know what other differences could there be between the two seemingly identical models? Any help in shedding light on this question would be highly appreciated.
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Old 12-20-19, 08:00 PM
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Many hubs are available with a choice of spoke holes, if the code is the same both hubs should be identical.
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Old 12-23-19, 10:18 AM
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Wilfred Laurier
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Almost definitely mechanically identical, just a different drilling pattern in the shell.

FWIW, it is my understanding that the internals of Shimano Nexus hubs can be swapped as a unit, from a known good or new one into an older or damaged one.
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Old 12-25-19, 05:03 PM
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Originally Posted by Wilfred Laurier View Post
Almost definitely mechanically identical, just a different drilling pattern in the shell.

FWIW, it is my understanding that the internals of Shimano Nexus hubs can be swapped as a unit, from a known good or new one into an older or damaged one.
Thanks for your response. I can buy a complete slightly used wheel with SG-8R36 HUB (which is also an upgrade) which is compatible with SG-8R31. Unfortunately, my HUB is drilled for 32 spokes while the SG-8R36 HUB was drilled for 36 spokes. So instead of replacing the entire HUB unit for unit, I'll have to remove the "guts" of the GS-8R31 and replace it with the "guts" from SG-8R36. Lots of extra work but I have not been lucky in finding a HUB with 32 holes.
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Old 12-26-19, 05:23 PM
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SG-8R31 and SG-8R36 internals should be interchangeable, but SG-8R22/27 internals are not. They have pawls on the direct drive to the hub shell where the 31 and 36 have roller clutches. All use roller clutches for the high speed drive.
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Old 12-29-19, 04:50 PM
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It is very easy to swap from one hub to another. As you sit on the bike. It is jus a matter of undoing the left hand cone lock nut and undoing the cone. ( With the wheel removed with the drive side of the spindle clamped in the vice. ) The bearings are caged so won't just fall out. Lift old wheel/hub off and grease bearings and replace with New hub,cone and locknut and carefully adjust cone to remove any play and lock with lock nut. If unsure get lbs to correct bearing adjustment.
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Old 12-30-19, 12:02 AM
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Originally Posted by Cyclepeasant View Post
It is very easy to swap from one hub to another. As you sit on the bike. It is jus a matter of undoing the left hand cone lock nut and undoing the cone. ( With the wheel removed with the drive side of the spindle clamped in the vice. ) The bearings are caged so won't just fall out. Lift old wheel/hub off and grease bearings and replace with New hub,cone and locknut and carefully adjust cone to remove any play and lock with lock nut. If unsure get lbs to correct bearing adjustment.
Seems like an easy task. But my lbs quoted me $100 to do the job. Are they trying to take advantage of me because they sense that I'm a novice?
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Old 12-30-19, 03:06 AM
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Sounds expensive! Don't know what the hourly rate for bike shops is . In UK it's about £30-40p.h.
there is no way it's 3+ hours work.
I can dismantle,clean,,check and regrease an8speed hub in an hour, comfortable.
A straight swap with an quick inspection and regrease is 1/2hr.
Something most LBS should easily attain, provided,they have a technician with hub gear experience.
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Old 12-30-19, 09:45 AM
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Have you considered taking the original hub/wheel back to the LBS who serviced it? You paid good money for the repair why not address the issue with them?
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Old 12-31-19, 12:58 AM
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Originally Posted by Buzzkill53120 View Post
Have you considered taking the original hub/wheel back to the LBS who serviced it? You paid good money for the repair why not address the issue with them?
You made a good point. It was apparent that the tech hadn't done much, just cleaned the HUB, maybe added some lube. The reason why I didn't go back to that same store is this: why go back to a place that was, well, less than honest with you in the first place? I can't breeze down his neck while he's working. And even if I could, I don't know much about bike mechanics to be able to determine whether the tech is doing a good job or not. At any rate, the HUB continued to make exactly the same types of noises and then I was able to secure an almost new SG-8R36 which is an upgrade to SG-8R31. Life is too short. BTW, he tech informed that while swapping the gearing assembly he will also need to replace all the spokes. That surprised me - why can't he leave the existing spokes in place and simply swap the gearing assemblies?
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Old 12-31-19, 05:39 AM
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Originally Posted by Edichek View Post
........BTW, he tech informed that while swapping the gearing assembly he will also need to replace all the spokes. That surprised me - why can't he leave the existing spokes in place and simply swap the gearing assemblies?
Have you some mechanical nouse, or a mate who has?
You tube, digest, think, then get into it with some caution. Keep track with your digital camera.
When I rebuilt my Sachs S7 I settled on a Russian You Tube channel that was explicit; and easy to follow without words.
How hard can it be? Bicycle mechanics can chime in now. especially about replacing spoke when changing out hubs
I think that guy you spoke of was wanting to take advantage.

Last edited by slow_runner; 12-31-19 at 01:32 PM.
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Old 12-31-19, 11:24 AM
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When you had the hub serviced, did you take the whole in? If not, then the LBS would have no way to check it out. However, if you took the bike in, then take it back and have them road test it.
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Old 12-31-19, 02:21 PM
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Originally Posted by Buzzkill53120 View Post
When you had the hub serviced, did you take the whole in? If not, then the LBS would have no way to check it out. However, if you took the bike in, then take it back and have them road test it.
Hi, yes, I dropped off the bike at the store and a few days later picked it up. It shortly became apparent that nothing had been done. Just cleaned outside. BTW, do I really need to have all the spokes replaced when swapping gear assemblies? I just don't understand why the tech insists that this needs to be done. I thought all that ne needed to do was to open the HUB, take out the malfunctioning gear assembly, add some grease and then put in the good one. What does this have to do with spokes?
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Old 01-02-20, 06:34 PM
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Unless all the spokes are loose/worn/damaged,I can't believe they need replacing. A straight swap , check and lube then a roadtest on the bike is all that is required.
i would advise taking it to a cycle shop which sells a few hub geared bikes with IHG experienced technicians.
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Old 01-02-20, 06:45 PM
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I wonder if the technician thought you wanted the original rim building onto the newer hub? Hence ,new spokes required.
i would still try to get your money back or get the swapping of internals at a token price.
Surprised they never said that it hadn't made any difference after they "serviced" it!
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