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The Shimano Nexus and Alfine Components

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by Sheldon "Totally Enclosed" Brown
revised by John "and now, Fully Exposed" Allen
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Nexus Hub Cutaway

Planetary Gears Are Back!

Did You Ever Have A Three-Speed?

Do you remember how easily it shifted, even when you were stopped for a traffic light?

Do you remember how trouble-free it was?

Do you remember how the chain never fell off?

Do you remember how weather-proof the gear system was?

Do you remember how comfortable it was?

But...

You also probably remember the narrow range of gears, and the big jumps in between.

You probably remember the gap between gears, where your feet would spin freely, with no result.

You probably also remember how heavy your old "all steel" bicycle was,

and how badly the brakes worked in the rain...

The Good Without The Bad!

The Shimano Nexus group combines the best features of your old 3 speed, and eliminates the worst, thanks to modern materials and technology.

Nexus is a family of parts, but the most exciting part is the series of multi-speed hubs -- 3, 7, 8- and 11-speed versions are now available, as well as an old-fashioned 3-speed. The higher-end versions including the 11-speed are in the Alfine series, which use roller clutches to reduce rolling resistance ratchet noise.

The 7-speed was the first of these hubs. It compares very favorably with a typical 1970's 10-speed. The 8- and 11-speed hubs have a wider range:

Gearing system Range speeds
Alfine 11-speed 409% 11, even spacing with larger bottom step
Nexus/Alfine 8-speed 307% 8, mostly even
Nexus 7-speed 245% 7,
evenly spaced
1970s 10-speed 247% 8 usable,
uneven spacing.
Nexus 4-speed 184% Even spacing. Discontinued
Nexus 3-speed 186%Yes, they still make one...
Old 3-speed 178% 3, widely spaced

For details of the gearing of the Nexus and Alfine hubs, please consult the

On-line Gear Calculator for Internally-Geared Hubs

Other features of the Nexus system:

Nexus internal gear systems also incorporate all-weather braking systems. They are available in two forms, though not all in every number of speeds:

Both of these systems provide quite a good rear brake, which works as well in rain and snow as it does on a sunny spring afternoon.

There is also a front Rollerbrake available, but, in my opinion, a conventional cantilever brake is better for the front. I would not particularly recommend the Nexus front brake.

The high-end Alfine hubs use the Shimano CenterLock fitting, for Shimano's proprietary disc brake rotors.

Nexus Technical Page

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Converting an Existing Bicycle:

In some cases, it is possible to convert an existing bicycle to the use of a Nexus hub. I have a very nice 1970's Raleigh Competition racing frame which I have converted into a Nexus 7-speed.

Sheldon Brown's Nexus Raleigh Competition

Sheldon Brown's Nexus Raleigh Competition

Ideally, frames for use with the Nexus system should have horizontal dropouts. Bikes with vertical dropouts don't provide any way to adjust the chain tension, so you would need to install a chain tensioner (or a rear derailer) to regulate the chain tension.

If your bike has vertical dropouts, you need to order a special set of anti-rotation washers designed for vertical dropouts, or the cable routing will be incorrect.

Nexus hubs have a drop-out spacing between 127 and 135 mm. Older bicycles are typically narrower than that. In the case of steel (Cromoly) frames, it is usually possible to spread the rear triangle to the needed width. Any good bicycle mechanic will be able to do this, or you can do it yourself. If you leave off the Rollerbrake and use a thinner cone lockwasher on the left side, you can re-space a Nexus 7- or 8-speed hub to about 126 mm. Similarly, if your frame is made for 135 mm spacing, you can add spacers to the axle to fill in the gap.

Nexus Hubs for Sale at Harris Cyclery

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