Question about switching rear hub



Jun 11, 2012
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I have a felt cruiser with a nexus 3 speed internal hub. I would really like to switch it to a 8 speed hub if possible. I believe the axle diameter on the 8 speed hub is 5mm larger than the 3 speed. 127mm 3speed 132 mm 8 speed----Can any of u guys tell me if there is a way to get the 8 speed to fit my bike or should I scrap this idea? Any other suggestion are welcome or any other possible options. Are there any manufacturers that would work? Any help is appreciated... Thx
 
Jan 21, 2009
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Only 5 mm difference should be able to squeeze in there with no trouble.
 
Jun 11, 2012
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Hey Nick... The measurement I gave is the over locknut length on the hub which should match the dropouts. I realize I would need a different length of spokes if I was to use the same wheel but I was planning to buy a new wheel and install a 7 or 8 speed hub on it . Being an aluminum frame its not a good idea to try and spread the dropouts so I need a exact fit. I thought if someone on here has done it then maybe they could tell how they went about it. Thx for your replies.
 
Feb 20, 2012
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you should be able to spread the dropouts 5mm with your hands fairly easily with no real added stress to the frame.
 
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I took a Nexus 3 speed out of my Basman and put in a Nexus 8 speed and didn't have any difference in width at the dropouts. Went right in but you have to use a no-turn washer on each side. This is an SG-8R31 hub with a roller brake. Maybe a coaster brake one is different although I have a Nexus 7 with a coaster brake and it's the same width as the 3 speed.



 
Sep 29, 2008
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Cool hub with the disc brake. I love that chain too. Where did you find it? I have a Nexus 7 and it's been a great hub so far. Gary
 
Sep 21, 2008
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thats a roller brake, not a discbrake. The disc is just a heat sink for the brake.
In the 60s, cafe racer motorbikers fitted similar heat sink discs to there front hub brakes. They called them Bacon slicers, after the big meat cutting machine that Butchers have in there shop.

I think a Roller brake is much the same sort of thing as a Band brake. The cable pulls the lever and squeezes the mechanism to slow the wheel.

I used to work at a bike shop that sold bikes with those roller brakes on both wheels. I didnt like building them up, as they were tricky to attach the cables to them. Same with the gear cable into that ring round the cog. :roll:
 
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The roller brakes on mine work great. I've never had a bicycle with disk brakes so I don't know if it works better or not. I'll see if I have a picture of the inside of the roller brake before I put it on. You can see how it works when it's off. It has a hex shaped cam that has rollers on ramps and when you apply the brake the hex turns and the rollers press on the shoes inside the drum. They can generate quite a bit of heat and that's why they have the cooling fin. Some of them have quite large cooling fins. Most people think it's got disk brakes when they see it, especially since the fin rotates with the wheel when you're riding.

The chain is a Shimano NX-01 Oval Link. I've never found a source for them in the U.S. I get them from Ebay from a seller in England. It took 1 1/2 sets to do the Basman because of the length. The chain is sort of a pain to work with because it doesn't fit into the chain break due to the thickness of the oval plates. And the pins are different than normal chains. I've got a system down for working with it but I broke several links on the first bike I installed one on.
 
Jun 11, 2012
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Hey Nick, could give me an idea of of the difference in gear range in comparing the nexus 3 speed to the nexus 8 speed,, like how would 3 rd gear on the nexus 3 compare to 8 th gear on the nexus 8 ,are u satisfied with the range of gears on the 8? Is 8th gear strong enough? And is 1st gear light enough?.and what size of sprockets are u using...thx
 
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crazydave58 said:
Hey Nick, could give me an idea of of the difference in gear range in comparing the nexus 3 speed to the nexus 8 speed,, like how would 3 rd gear on the nexus 3 compare to 8 th gear on the nexus 8 ,are u satisfied with the range of gears on the 8? Is 8th gear strong enough? And is 1st gear light enough?.and what size of sprockets are u using...thx
The 8-speed has higher and lower ratios than the 7-speed which has higher and lower ratios than the 3=speed. Basically you are increasing the range and reducing the difference between gears. With the 3-speed on flat ground I was constantly changing between 2nd and 3rd gear. With the 8 I pretty much stay in 5th. I recently changed the rear sprocket from a 19t that was on the 3-speed to a 22t that came with my 7-speed. Gives me a bit better range for tackling hills. I've not ridden a bike with a Nexus 7 but I'm very happy with the 8-speed. Amazon has a great price on the better version of the 8-speed right now. This is the SG-8R36 and is $148.74. Same ratios but has better bearings. If I'd seen it before I bought mine I would have gone for that. I paid $100 for mine at the Electra warehouse sale but had to buy some parts separately that the Amazon one comes with. Either way the brake is separate.

Here are the ratios for the different Nexus hubs.

3-speed
0.733 - 1.000 - 1.364

7-speed
0.632 - 0.741 - 0.843 - 0.989 - 1.145 - 1.335 - 1.545

8-speed
0.527 - 0.644 - 0.748 - 0.851 - 1.000 - 1.223 - 1.419 - 1.615
 
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