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  1. #1
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    Shimano Nexus 3 speed hub review

    I finally bought one of these for my commuter. I searched diligently to find reviews for this hub before I bought it, most of what I found turned up here.

    This is the Shimano SG- 3D55 3 speed hub. 32 hole, 135mm, centerlock disc-ready, purportedly having a silent clutch (more on that later). The only production bike I've found to have this hub was a Specialized Globe model from a couple of years ago. I've been riding a single speed for my commute to work, but it's a bit of grind on the hills, especially when it's raining and blowing. So I built this up.


    It's the Salsa single speed Casseroll, which I've fitted with the 3 speed hub. The Salsa has forward facing horizontal dropouts, which is ideal since you can remove the rear wheel without taking off the rear fender. I don't have much experience with IGH's although I did test ride an Alfine 8 speed at a local bike shop. The Alfine works well, but it's quite chunky and I didn't want a grip shifter. The SG3d55 is relatively cheap, $125, add a shifter and bell crank for about $20. It is also about a pound lighter.


    The SG-3d55 has gearing that is the same as all other Shimano 3 speed hubs. 1st gear is .733:1 second gear is 1:1 third gear is 1:1.36. I am running 48t/19t cogs, which results in drivetrain gains of 1.85, 2.53, and 3.44. The gearing is fairly widely spaced, about the same as shifting from your smaller front chainring to the big chainring on a typical road bike (39t/53t). I ride in second gear the most. Overall it works pretty well, though sometimes I find myself wanting something in between 2nd and 3rd gear.

    Shifting. Upshifting is good. Moderate load can be applied to the pedals and the bike will still up shift quickly and quietly. Downshifting . . . not so much. For a clean downshift you pretty much have to pause in pedaling for a clean shift. Seems to be more of an issue for shifting 2nd to 1st than 3rd to 2nd. Just like any of the current cruiser bikes, the bell crank translates the cable pull of the shifter into a pushing force against the pushrod within the axle. Lateral position of the push rod determines what gear the hub is in. The bell crank is fixed by a set screw. Removing the rear wheel first requires removing the bell crank, then loosening the axle nuts. I didn't want a grip shifter, so I dove into the old parts bin and found a Suntour 7speed indexed downtube shifter. Coincidentally, 2 clicks on the suntour works out to one gear on the shimano hub. With a little tuning, the system works pretty well. I run a bare shifter cable from the shifter, under the BB and straight to the bell crank -- no cable housings. This makes for a crisp system.

    Aside from the option for a disc brake, the biggest selling point of this hub is the "silent clutch". Well, that claim is only partially true. The hub is truly silent in first gear, both coasting and pedaling. Second gear is typical hub behavior, silent while pedaling, ratcheting while coasting. Third gear is . . . a disappointment. The hub ratchets both while coasting and pedaling. Not so silent. As far as I recall, the Alfine does not have this problem, so it's certainly possible to design around it.

    Overall, I like the hub. I think the simplicity and compactness of the 3 speed IGH is perfect for commuting. Fewer moving parts than an 8 speed, so less to go wrong. While the external bell crank is not very cool looking, it works well and wheel removal is easy. The gearing works for me pretty well, if anything it could be a bit closer spaced, but it works fine as it is. The biggest annoyance is the ratcheting in third gear, which is only slightly moderated by the fact that I use this gear the least. Improved downshifting would be nice as well.

  2. #2
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    Spiffy setup with the nekked cable exiting directly. Me likey.

    It's too bad 1:1 can't be the #3 gear. I could see some value in that.

    Very clean build.
    speedub.nate
    MTBR Hiatus UFN

  3. #3
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    Thanks for the review. I wonder if any of the less than optimal shifting and gear noise could be caused by the non-standard shifter config?
    baker

  4. #4
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    The SG-3D55 is Shimano's good ol' Nexus three speed in an aluminum shell with the main drive ratchet replaced by a roller clutch. As mentioned, the two regular over-run ratchets are still in place.

    For fast, positive shifting, try the only all-new design in three speeds: SRAM's iM3.

    My review:
    http://groups.yahoo.com/group/Geared...threaded=1&l=1

    Another review:
    http://groups.yahoo.com/group/Geared...threaded=1&l=1

    JD

  5. #5
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    Sounds interesting. I hadn't really heard anything about the IM3 hub. Does it ratchet in 3rd gear? I didn't see any mention of that in the reviews. After a quick search, it doesn't appear to be available in a 32 hole version.

  6. #6
    pedal pusher
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    That hub comes with a 19T cog, correct?

    Is it a standard freewheel type in case one would want to put on a different size?

  7. #7
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    Quote Originally Posted by f3rg
    Is it a standard freewheel type in case one would want to put on a different size?
    No. In case one would want to put on a different size, it is a standard IGH type, as used on Sturmey 3-, 4-, 5- and 7-speed hubs, SRAM 3-, 5- and 7-speed hubs, Shimano 3-, 4-, 7- and 8-speed hubs, and countless SS coaster brake hubs. These are available in 13T to 23T, in both narrow (for 3/32 chain) and wide (for 1/8 chain) thicknesses from several manufacturers.

    HTH,
    JD

  8. #8
    pedal pusher
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    Thanks, John!

  9. #9
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  10. #10
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    Quote Originally Posted by smokey_z
    The SG3D55 is relatively cheap, $125, add a shifter and bell crank for about $20.
    FWIW, the SG-3D55 is the most expensive three-speed hub on the N.A. market (apart from the DualDrive and S3X, which are really something different, anyway).

    The SG-3D55 would be around twice as expensive as an SG-3R40, if Shimano only offered that hub aftermarket in America (it is offered as OEM equiment on factory bikes).

    Comparing street prices, the beautiful Sturmey-Archer SRF-3 and lightning-fast shifting, inboard cable SRAM iMotion3 are also only just over half as much as the SG-3D55.

    JD

  11. #11
    pedal pusher
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    Quote Originally Posted by john_dalhart
    FWIW, the SG-3D55 is the most expensive three-speed hub on the N.A. market (apart from the DualDrive and S3X, which are really something different, anyway).

    The SG-3D55 would be around twice as expensive as an SG-3R40, if Shimano only offered that hub aftermarket in America (it is offered as OEM equiment on factory bikes).

    Comparing street prices, the beautiful Sturmey-Archer SRF-3 and lightning-fast shifting, inboard cable SRAM iMotion3 are also only just over half as much as the SG-3D55.

    JD
    They're cheaper, but also seem to weigh significantly more.

  12. #12
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    Hub follow up

    It's been a little short of a year and a half since I put the nexus 3 speed hub into service. I thought I would follow up with how the hub has been performing.

    I have been riding the hub for my commute to work for almost a year and half. It's about a 18 mile round trip, with a mix of flats and small hills. I live in Portland, where it happens to rain quite a bit throughout the year, except July through September. My original goal in building this bike was to have a very low maintenance commuter that didn't feel like a tank to ride. Since I've built it, I have done very little maintence, except oiling the chain, changing tires, and adjusting brake pads. Recently I noticed that the 3 speed hub was making an intermittent click/ creak, so I decided to check it out.

    What I found right away was that the drive side of the hub had been contaminated with water and dirt. The non-drive side looked pretty much like I expected, the originally white grease had turned to a neutral grey color from the natural breaking in process of metal to metal contact. On the drive side, the outer most bearings, cone and retainer were covered in rust, with little grease remaining. The color difference is pretty obvious. The bearings and retainer need replacement, possibly the cone and cog carrier.
    So while this hub offers some higher performance features in terms of weight and the clutch, it lacks the type of seals that are needed for year round riding in the pacific northwest. At the least there should be a double set of seals on the drive side to reduce water ingress. I plan to rebuild the hub with new bearings and see how it performs, however I doubt it last more than one or two more winters before the entire hub is shot.

  13. #13
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    Quote Originally Posted by smokey_z
    ..
    So while this hub offers some higher performance features in terms of weight and the clutch, it lacks the type of seals that are needed for year round riding in the pacific northwest. At the least there should be a double set of seals on the drive side to reduce water ingress. I plan to rebuild the hub with new bearings and see how it performs, however I doubt it last more than one or two more winters before the entire hub is shot.
    interesting. Or maybe in your conditions it needs to repacked with grease every few months?

  14. #14
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    I am currently building a wheel with one of these hubs and I am trying to work out what additional bits I need. I have the disc spline hub, I have the shifter and I have the bell crank and non turn washer. I was wondering what size push rod I needed and what other additional parts I might need?

  15. #15
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    You'll need a couple of axle nuts, if you don't already have them. Then you just have to figure out your cable routing from the shifter to the bell crank. I routed mine through a guide under the bottom bracket, road style. I decided to go without cable housing as it tends to add friction. Only drawback I can see is that the position of the axle in the dropouts affects tuning of the shifter. I am able to fine tune the system by sliding the bottom bracket cable guide laterally to make small adjustment in the overall path length. I'l have to check the push rod length later.

  16. #16
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    smokey_z, thanks for your pictures and review.
    It's really sad that a bicycle manufactor doesn't include features to protect the hub from rain. I have a older hub ; SG-3C41, and it needs maintenance as it grinds.

    Love your bike. I have same frame, but older.

  17. #17
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    from the original post I suspect you tested a Nexus-8 rather than the Alfine-8? The nexus has the grip shifter and the alfine has a trigger shifter. Overall I do very much like your very sensible build, sometimes an extra gear or two is needed.

    I also have that continuing struggle with the 3-speed IGH, I do favor a stealthy quiet ride and have never been able to get that. I had two bikes with 3-speed IGH both the Sram and Shimano, both have clackety-clack. The sram I converted to a heavy but superb Nuvinci n-360..utterly silent! and my other I'm preparing to convert over to a nexus-8 coaster. Admittedly these are on more fun/recreation bikes and not a workhorse so I'm fine with the sizable weight penalty. My Alfine equipped bike is dead silent and I love it!

    As I understand, it's the basic mechanical 'simplicity' (relative) of the 3-speeds w/ planetary gears that introduce that gear noise, it also allows them to manage maintaining a favorable weight and price point and that is their strength. I know I'll pony up a modest extra for that well sealed and silent 3-speed.

    I've been curious about switching my SS road (steamroller) over to a Sturmy KB2 hub. I too have enough hills about me that a devotion to SS when riding decidedly pedestrian can be a chore. Its fine to grin and suffer when it's about exercise and fitness but sometimes I just am trying to slowpoke it home, my interest lay primarily in climbing hills and not more speed so a two speed might be okay.

    Bike is a beaut! Great color!! Gratitudes on the review also.

  18. #18
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    MTB and Nexus 3 speed

    How will the Nexus 3 speed hub hold up to mountain biking? I'd like to try one out for a Full suspension bike.

  19. #19
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    Quote Originally Posted by cottonball View Post
    How will the Nexus 3 speed hub hold up to mountain biking? I'd like to try one out for a Full suspension bike.
    Currently testing one on a Surly Pugsley. So far it rolls well but on really rough rides it self shifts which is annoying. After some adjustment it has gotten better. Physically it's holding up well.

  20. #20
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    What do you guys think of the spacing on this hub, I can't feel much difference if any difference at all between 1st and 2nd gear, I am on a 34x16.

  21. #21
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    Quote Originally Posted by dblspeed View Post
    What do you guys think of the spacing on this hub, I can't feel much difference if any difference at all between 1st and 2nd gear, I am on a 34x16.
    34x19 (w/ 29" tires) gave me a more useable ratio, but keeping up on singletrack with a 40lb bike proved to be standing room only on the pedals! I found that on flat ground I was typically running in 3rd, there was no sense in having 3rd for downhill/downwind only.

    you could try 34x17 or 18, and get more climb if you don't use 3rd much.


    As a side note, I am upgrading to alfine 8 for more useable offroad gearing while still keeping the top speed the same.

  22. #22
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    Quote Originally Posted by roobydoo View Post
    34x19 (w/ 29" tires) gave me a more useable ratio, but keeping up on singletrack with a 40lb bike proved to be standing room only on the pedals! I found that on flat ground I was typically running in 3rd, there was no sense in having 3rd for downhill/downwind only.

    you could try 34x17 or 18, and get more climb if you don't use 3rd much.


    As a side note, I am upgrading to alfine 8 for more useable offroad gearing while still keeping the top speed the same.
    mine was actually an issue of the hub not shifting, after some trial and error and a lot of research I found out I had been provided with the wrong pushrod (too short). After installing the right pushrod the hub works correctly.

    I own a Rohloff as well and I bought this hub as an alternative to either the SS or the Rohloff for flat to hilly terrain, and it works really great for this purpose, much lighter than the Rohloff, moderately heavier than the SS, it offers just enough gear options to be faster on the flats and the downhills, save your legs on the grinds, and keep up with the gearies when needed (ie, on pavement). That said I'd be weary of using an Alfine instead of the Rohloff for riding in real mountains, given the proven, bombproof shifting and general performance of the latter.

  23. #23
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    What are the exact sprockets inside the Nexus 3?
    I read that the OP mentioned some ratios but I must be new still that I cannot convert that on to "T" terms.

    I looked at Shimanos web site and, for the Nexus 3, shows 16T, 18T, 19T, 20T, 21T, 22T & 23T. I figure that their specs sheet makes reference that it can have any 3 combination from 16T to 23T but my local dealer told me that the Nexus 3 is only one and cannot be customized... he did not know what is the gearing inside!

    I just bought a bike that has 39T at the Chainring and the Nexus 3... I am just curios of what exactly I have.

    Thanks!

  24. #24
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    Count the number of teeth on your rear cog. Multiply that number times the gear ratios to get your effective rear gearing.

    Ratios
    0.733
    1.000
    1.364

    So, if your cog has 18 teeth, your effective rear gears are: 13.2, 18, and 24.5
    baker

  25. #25
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    Quote Originally Posted by baker View Post
    Count the number of teeth on your rear cog. Multiply that number times the gear ratios to get your effective rear gearing.

    Ratios
    0.733
    1.000
    1.364

    So, if your cog has 18 teeth, your effective rear gears are: 13.2, 18, and 24.5
    Thanks for your answer BUT the Nexus 3 has the cogs inside the hub. Cannot see the cogs, cannot count the teeth unless the hub is completely disassembled and opened hence my question...

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