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.

 

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?

 

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_hub_bikes/message/1397?threaded=1&l=1

Another review:
http://groups.yahoo.com/group/Geared_hub_bikes/message/1922?threaded=1&l=1

JD

 

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.

 

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?

 

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

 

Thanks, John!

 

...

 

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

 

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.

 

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.

 

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.

wondering if you considered regular (once a month?) oiling of the hub? I've got one built as a commuter wheelset and I am planning to just inject heavy suspension oil (30wt) down where the shift pin goes and just let it seep out slowly. I put 5ml in at a time and so far have had any leak onto the rim (I'm using disks so it wouldn't matter anyway). Suspension fluid shouldn't be too hard on any seals in the hub I hope as otherwise it would eat your fork seals?

 

..
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?

 

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?

 

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.

 

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.

 

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.

 

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.

 

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.

 

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.

 

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!

 

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...

 

You don't need to count the cogs inside. The hub uses various combinations of those cogs to produce the ratios that Baker listed. The ratios X whatever of the 7 sprockets you choose determines the effective gear.

As Baker said the 18T gives 13.2, 18, 24.5

And, as Baker said, count the number of teeth on the sprocket on the hub.

When you have that # multiply it by .733, 1, 1.364 to get your three 'gears'

For instance, using the 22T gives you 16.126, 22, 30.008....

Drew

 

You don't need to count the cogs inside. The hub uses various combinations of those cogs to produce the ratios that Baker listed. The ratios X whatever of the 7 sprockets you choose determines the effective gear.

As Baker said the 18T gives 13.2, 18, 24.5

And, as Baker said, count the number of teeth on the sprocket on the hub.

When you have that # multiply it by .733, 1, 1.364 to get your three 'gears'

For instance, using the 22T gives you 16.126, 22, 30.008....

Drew

Got it... got it now! Sorry Baker I did not get it the first time!

An internal gear hub, such as the Nexus 3, uses a planetary gear system to determine its ratios. It doesn't have cogs like you find on a freewheel or cassette. The Shimano specs that show a range of available cogs to use with the Nexus 3 are actually talking about the single rear cog that can be switched out. I have rear cogs ranging from 18t to 22t that will fit on my Nexus 3, but only one can be fitted at a time. Changing the rear cog is simple. Doing so will change all three gears of the hub to be either higher or lower. There isn't a way to change individual gears in the hub, though that would be nice.

You can use a gear calculator to compare the gear ratios in the Nexus 3 to cassette cogs. Here is one that I use, as it displays the results in a nice graph:

kstoerz.com | visual drivetrain comparison tool

You change the IGH field to Nexus Inter-3 when entering your data.

I used to have a Nexus 3 mated to a 700c wheel. With a 39t chainring and 19t rear cog, the three gear ratios in the Nexus 3 were equivalent to using 26t, 19t, and 14t cogs on a cassette (also with a 39t chainring and 700c wheel).

Great link!
Took me a while to understand the concept but I stand corrected!
Thanks

Maybe he meant to ask how many pawls are inside the hub - as in how quickly will drive engage?

Thank you for sharing and trying to make me look less stupid! :thumbsup:
I was confused but corrected.

 

Maybe he meant to ask how many pawls are inside the hub - as in how quickly will drive engage?

 

No worries GT *in-use*, this stuff isn't straightforward when you move from a regualr drivetrain over to IGH...

 

Shifter question

So, would the SA thumb shifter work with this hub? I would like to set one of these Nexus up on a drop bar bike and don't like the idea of their twist shifter on the bar end.

Thanks, Matt

 

So, would the SA thumb shifter work with this hub?

No.

I would like to set one of these Nexus up on a drop bar bike and don't like the idea of their twist shifter on the bar end.

If you're so enamored with the Shimano hub you've named one of you children Nexus, there are ways to use a drop bar shifter with this hub. Probably more straightforward though just to use a Sturmey three-speed hub from the AW-NIG family on that drop bar bike, then you'll have a choice of factory classic trigger, modern trigger, thumb, twist, bar end, braze-on downtube or seatpost shifters.

In comparison to Shimano and SRAM IGHs, Sturmey hubs have the additional advantage in NA of parts support.

JD

 

I use a Sturmey Archer S-RF3 on one of my drop bar bikes. The SA bar-end shifter works great. Makes for a great drop bar commuter bike.

I used to have a Nexus 3 wheel, but didn't use it on this bike. I couldn't find a satisfactory shifter arrangement. I ended up selling the wheel to cover the cost of the new SA hub.