Search sheldonbrown.com and sheldonbrown.org
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?
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...
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:
|Alfine 11-speed||409%||11, even spacing with larger bottom step|
|Nexus/Alfine 8-speed||307%||8, mostly even|
|Nexus 7-speed||245%||7, |
|1970s 10-speed||247%||8 usable, |
|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
Nexus internal gear systems also incorporate all-weather braking systems. They are available in two forms, though not all in every number of speeds:
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.
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.
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.