Shimano Nexus und Alfine Acht-Gang-Naben: Unterschied zwischen den Versionen

''Die Alfine SG-S500 basierenden Modelle (Naben und Laufradsätze) haben jeweils eine "A" und eine "B" Version. Die "A" Versionen haben Innenleben mit zwei Rollengesperren. Das heißt, sie haben Sperrklinken auf der rechten Seite und das Hauptrollengesperre (Mitte des Nabenkörpers) wird durch eine Schleppfeder vorgespannt, die in den Nabenkörper eingesetzt wird (Diesen AUfabeu findet man auch bei den meisten Rücktrittbremsenversionen und bei Nexus Naben mit Sperrklinken wie zum Beispiel SG-8R25 und SG-8R27).<br><br>(Das Bild links zeigt eine Schleppfeder, wie sie in den Nabenkörper eingesetzt werden sollte).<br><br>Ein Unterschied der SG-5500-A Naben (und mancher Nexus Modelle) ist der Umstand, dass die Rollenheltaringe mit Zinnen bewhert sind - die Spitzen nach links heruasragen und die Schleppfeder mitnehmen. Dahingegen haben die Nexus SG-8R25 und SG-8R27 (Rollerbrake/auch bremsenlos, später mit Rücktrittbremse und auch Alfine) Naben keine Zinnenbewehrung auf ihren Rollenhalteringen. Stattdessen haben sie einen Vorsprung an der Trägereinheit. Diese Zinnenbewehrung kann sehr leicht beschädigt werden.<br><br>Es gibt eine teileliste der SG-S500 "A" Versionen auf der Website von [https://web.archive.org/web/20150620164713/http://www.paul-lange.de/support/shimano/explosionszeichnungen_archiv/SG//SG-S500.PDF Paul Lange (inzwischen im Internet Archive)], die hilfreich die Austauschbarkeiten mit einigen Nexus 8 Nabenvarianten aufzeigt.<br><br>''

[[Datei:Nexusvsalfineaxleunitsm.jpg|right|Nexus und Alfine Achsen]]While the axle assemblies are mostly identical, a section of the left end of the Alfine axle shown, as well as others, is fatter to withstand the bending moment from the optional disc brake, as shown in the image at the right (courtesy Aaron's Bike Repair). The Alfine left bearing cone threads onto the wider part of the axle. The Alfine requires a wider overlocknut distance than the Nexus without Rollerbrake. There are several different left-bearing-cone part numbers. Mix and match at your own risk.

The Rollerbrake and coaster brake are weatherproof, but drag slightly when not engaged, so if efficiency is a concern, avoid them. They also overheat when used on long downhill runs. We don't know for sure whether any coaster-brake model has needle-bearing pinions, but it appears not.

For all Nexus and Alfine 8-speed hubs except the S7000 series Alfine hubs, the cable is loosest in the lowest gear. The S7000 series is the opposite, and the cassette joint and axle assemblies are significantly different.

Bruce Dance sends the following warning:

It is very easy for parts (pawls or balls) to come adrift during assembly. For example commonly a ball (or balls) can come adrift from the ring bearing, either during assembly, or even in service (if the bearing adjustment slackens). This very often results in destruction of the hub internal, especially in the single or dual-roller hubs with a pawl-drive in the RHS, because the balls can easily get into where the pawls sit and then break them.<br><br>I therefore advise anyone working on these hubs to assemble the internal into the hub shell without the sprocket and the dust cover, and to be sure that all the balls are still present, and that the cone adjustment is pretty much done before the covers are refitted. Similarly if the hub has a pawl drive on the LHS (for gear 1 and 5), the internal ought to be rotated backwards as it is installed, else pawls may be dislodged.<br><br>I have seen one hub in which a roller came adrift (presumably during the factory assembly, since they cannot easily come out in service) and this smashed the hub shell to pieces. Kind of ugly.

Shimano has information on most but not all 8-speed models. These hubs have gone through several minor design changes, resulting in new model numbers and parts incompatibilities. Hubs parts numbers start with SG but there are also other parts listed, including brakes and shift levers. globeThese pages are available in multiple languages, with a language list box at the upper right corner of the screen.

Several Shimano dealer's manuals offer information on installation, adjustment and maintenance of newer hubs:

*    Sprocket installation, wheel installation, cable shifting for the SG-8C31, SG-8R31, SG-8R36, SG-8R60, SG-C6000, SG-C6010 and SG-C6060 series Nexus hubs.

Shimano made information sheets available individually for earlier hubs. The tables below list hubs in each series individually in order from newest to oldest, describing their differences, linking to information from various sources. The right-hand column holds links to available information. Dealer's manuals with information commont to many hubs areomitted. Shimano has provided rebuilding instructions for only one model, though others are similar.

To find which parts from newer models fit older ones, open the search function in your browser to look on this page for instances of an older hub's model number. Compatibility may cascade to yet another hub or hubs. At the small-parts level, there is much more interchangeability than is shown. Parts for some older models may no longer be available.

There is some interchangeability between Alfine and Nexus models. When a model number in the interchangeability column is in italics, the entire internal assembly is compatible.

* [https://web.archive.org/web/20130818045722/http://www.shimano.com/publish/content/global_cycle/en/us/index/tech_support/tech_tips.download.-Par50lparsys-0016-downloadFile.html/09%29%20Differences%20Between%20Hubs.pdf Unterschiede zwiechen Alfine und Nexus Naben aus dem jahr 2013 (englisch/PDF)].  

==Alfine 8-Gang Scheibenbremsen- und bremsenlose Modelle==

==Nexus 8-Gang Freilauf- und Rollerbrake-Modelle==

==Nexus 8-Gang Rücktrittbremsenmodelle==

In some cases, it is possible to convert an existing bicycle to the use of a Nexus hub.

 

I converted my early '70s Raleigh International, using a Nexus 8-speed.

I like the Nexus 8-speed a lot better than the 7-speed version.

Sheldon Brown's Nexus Raleigh International

 

Sheldon Brown's Nexus Raleigh International

Ideally, the frame should have a dropout spacing of 127 to 135 mm to fit one of the Nexus hubs. 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. Alfine hubs require 135mm spacing.

If you leave off the Rollerbrake ®, you can get the spacing down to about 126 mm, as already mentioned. This is what I did on my Nexus bike. The Rollerbrake ® is a separate module, and when you buy the hub it is not even installed. (The brake unit would get in the way of fitting the spokes through the hub flange, so it has to be installed after the wheel has been built.)