Sachs und SRAM Nabenschaltungen

The German company Fichtel & Sachs, often called only "Sachs", started making internal-gear hubs in the early 20th century. In 1997, the American company SRAM acquired Fichtel & Sachs, and so recent products carry the SRAM name. SRAM quit making internal-gear hubs in February, 2017, citing a race to the bottom in the market, and the increasing popularity of e-bikes.

In the mid-20th century, Sachs specialized in products for utility cyclists -- two-speed kickback hubs, three-speed hubs and coaster brakes -- while Sturmey-Archer offered a broader product line, including many narrow-ratio hubs intended for use by avid recreational cyclists and racers.

Starting in the 1980s, Sachs expanded its line of internal-gear hubs to include hybrid gearing systems -- first the Orbit, a two-speed hub with proprietary sprockets, then the 3 x 7 followed by the 3 x 8, and 3 x 9 DualDrive 2 systems and the 3 x 10 DualDrive 3 using a three-speed internal-gear hub and Shimano-compatible cassettes. These newer hubs are especially useful on small-wheel bicycles, because the step-up top gear avoids the need for an extra-large chainwheel. Sachs also introduced 5-speed and 7-speed models and the Elan, a very large and heavy 12-speed hub which was a marketing failure. In the 2007 model year, SRAM introduced the i-Motion 9-speed hub. It was withdrawn, and as of 2014, SRAM offered an 8-speed hub, the G8, and a different 9-speed, the G9, but they also were withdrawn. In 2013, manufacture of SRAM internal-gear hubs was moved from Germany to Taiwan, though engineering was still in Schweinfurt, Germany and in 2017, as described, the line of internal-gear hubs was discontinued..

Stärken und Schwächen

SRAM internal-gear hubs are notable for the fine quality of machining of their internal parts. Gear-tooth surfaces and bearing races are smooth. The SRAM 3-speed, in particular, has higher measured drive efficiency than other 3-speed hubs, possibly due to the quality of the machining.

Most Sachs/SRAM internal-gear hubs are quite rugged, like classic Sturmey-Archer hubs, with simple and conservative mechanical design. Exceptions are the i-Motion 9 and Elan, which were overcomplicated and failure-prone. Older hubs shifted with pullchains, but one weakness with recent hubs is the plastic "clickbox" shifter mechanism which clamps onto the right end of the hub axle and is vulnerable to damage. A guard is sold, and it should always be installed. With the Elan and the 8- and 9-speed hubs, SRAM abandoned the "clickbox" for a pulley mechanism inboard of the right dropout.

Older Sachs 3-speeds and the 3 x 7 used a trigger shifter like Sturmey-Archer's, which could be fastened to any handlebar. A Sturmey-Archer trigger also will work with these hubs. A Sachs trigger will not work with a Sturmey-Archer hub, which needs a longer cable pull between the top and middle gear. An old Shimano drop-bar front-indexing STI shifter for triple chainwheels also works with a Sachs hub -- my Bike Friday has Shimano RSX STI brake-lever shifters, and the hub shifts flawlessly. (Bike Friday adds a small return spring to the cable to take up extra slack in the top gear. You need to do that too.) The newer SRAM hubs which use a clickbox were generally available only with twist shifters that fit flat handlebars. SRAM's assumption seems to have been that performance-oriented bicyclists don't care to use internal-gear hubs -- a bit of a self-fulfilling prophecy. There are various tricks to make the SRAM shifters compatible with drop bars -- for example, attaching a mountain-bike bar end to the stem. Aftermarket shifters also are reported to be in the works.

The 5-and 7-speed models with clickboxes use a single cable and concentric pushrods, with a dual bellcrank inside the clickbox. I've considered modifying a 7-speed to use a pullchain on the left side and bellcrank on the right.

The DualDrive hubs and Spectro T3 are supposed to be used only with their proprietary shifters, but they have a pullrod, not a pushrod, suggesting that a conversion to use a pullchain might be possible. Shimano-compatible cassettes that attach to DualDrive hubs work with a wide range of derailers and shifters.

The DualDrive hubs have aluminum shells and are relatively light in weight. Other than this, SRAM has paid relatively little attention to weight reduction over most of its internal-gear hub product line. Many models have been available only with heavy steel shells. The Spectro S7, for example, was made in three versions -- with no brake, with a coaster brake and with a drum brake. They all weigh about the same. You might expect the drum brake version to weigh more, but it is the only one with an aluminum alloy shell. The steel shells of the other 7-speeds are very thick and heavy.

The i-Motion 9 9-speed hub, introduced in 2006 (and since discontinued) has been described as a "cannonball" because of its size and weight! A version with a carbon fiber shell was marketed, but the weight of the internal parts is still substantial. The G8 8-speed hub, introduced in 2013, and G9, introduced in 2014 and since withdrawn, are larger but lighter and have a much simpler internal mechanism.

Schmierung

Many Sachs/SRAM hubs have coaster brakes, and these hubs must be lubricated with grease -- often two types of grease: one for the gear mechanism, so it doesn't make the pawls stick; another for the brake parts, to resist heat buildup.

Other recent Sachs and SRAM internal-gear hubs also use grease lubrication, and also have no oil cap. Except for the hubs with rotary (pulley) shifting, these hubs all allow addition of oil by removing the shifter parts and squirting oil into the hollow end of the axle. (The disk-brake version of the i-Motion 9 can, however, be lubricated through one of the disk-brake bolt holes at the left side. After disassembling some of the other disc brake models so metal chips can be cleaned out, drilling through one of the disc brake mounting holes allows it to be used as an oil port.). Oil is preferable for drag reduction, and because it can be replenished without disassembling the hub. Caution is in order not to use too much oil when it could seep through the bearing into a drum brake

Phil Wood Tenacious Oil is a good choice, if used in moderation and replenished once every thousand miles or so, or at least once every couple of years. Too much oil will get messy, while stale Phil oil will gum up and can make the pawls stick. The stickiness that keeps Phil Wood oil from being messy also allows it to gum up.

Also see the more general advice on this site about lubricating internal-gear hubs, and on types of oil.

Favoriten

My favorite Sachs/SRAM hubs are discontinued models -- the 3 x 7 DualDrive, discontinued in 2000, and the S7 7-speed with drum brake, discontinued in 2010.

The 3 x 7, unlike the later DualDrive models, can take an 11-tooth sprocket only after modifying the cassette body or adding a spacer as described here. Bike Friday modified the cassette body on its bicycles. I prefer the 3 x 7 over the more recent DualDrive models because the 3 x 7 has pullchain shifting, no vulnerable clickbox, and compatibility with drop-bar shifters. I equipped the 3 x 7 on my Bike Friday with a 13-15-17-19-21-24-28 cassette, so the hub's high and low gears each gave me two additional nicely-spaced speeds. Then I found a 33-tooth dished sprocket in Sheldon's basement and added that, widening the range -- see details about putting 8 or 9 sprockets on a 7-speed body here.

The S7 7-speed hub can be set up for an overall range from 27 through 82 gear inches, excellent for utility riding in a hilly area. The weight of the drum-brake version is reasonable, thanks to the aluminum shell. I plan to build an S7 into a wheel for a Raleigh Twenty.

I have spares of both the S7 and 3 x 7 hubs or I wouldn't be using them.

The G8 and G9 look promising for urban use, but I don't have hands-on experience with them.

Ersatzteilverfügbarkeit

Aaron's Bicycle Repair in Seattle, Washington, USA specializes in repair of internal-gear hubs and stocks parts for SRAM hubs including discontinued models.

Other options? I needed two internal parts for a 3 x 9 DualDrive hub. Bike Friday has installed DualDrive hubs on many of its small-wheel bicycles, and so I contacted Bike Friday's German distributor -- writing in German, yet! I found that the parts would cost me over $200, nearly the full price of a complete internal assembly.

Then I contacted Bike Friday directly. Bingo! Bike Friday cannibalizes returned DualDrive hubs to maintain a supply of spare parts. Tim Link at Bike Friday was able to send me the needed parts for $30. Thanks Tim! If you also need parts for a DualDrive hub, you might give Bike Friday a call.

In Europe, Sachs/SRAM hubs are common and spare parts, both new and used, are more widely available. They are going to be harder to get, now that production has been discontinued.

The axle threading of most SRAM internal-gear hubs is unusual, 10.5mm x 26 TPI, but close enough to that of many Sturmey-Archer hubs (13/32 x 26 TPI) that Sturmey-Archer axle nuts are usable in a pinch. The i-Motion 9, G8 and G9 use common 10 x 1mm threaded axle nuts.

Fehlerbehebung, Wartung und Wiederaufbau

My intention here is to provide the best information I can on rebuilding Sachs/SRAM hubs.

You do well to keep a spare hub for parts.

The first thing to check if a hub doesn't get all the gears is whether the problem is in the shifter, or the hub.

On older hubs with a pullchain, the chain should only be able to pull out a tiny bit farther in its tightest position. Having established this, the hub should shift correctly into all of the gears. If an indexed Shimano brake-shift lever is used to shift a 3 x 7 hub, as on some Bike Fridays, there needs to be an additional return spring on the cable to latch the shift lever. Bike Friday can supply this item.

The 5- and 7-speed hubs use dual, concentric pushrods. With the clickbox removed, the hub should be in its lowest gear. Pushing the outer pushrod in should shift the hub to the middle (direct drive) and highest gear. Pushing the inner pushrod in should shift the hub from low, to second, and in the 7-speed, to third gear. If the clickbox doesn't shift the hub to these gears, then it is the problem. If these gears work with the clickbox installed but the 4th gear of the 5-speed, or 5th and 6th of the 7-speed don't work, you may have to push on both rods at once to isolate the problem. You may need an assistant to help with this.

If a DualDrive or other three-speed hub with a pullrod doesn't shift properly, remove the clickbox and pull out the pullrod (which has a head with a screwdriver slot) as far as it will go, while spinning the rear wheel forward so the shifting mechanism will release. Stop the wheel, hold the rod in the outermost position with pliers, turn the crank forward and see whether the hub is in low gear (the wheel turns slower than the sprocket). Release the rod in two steps and you should get middle and high gear. If so, the problem is with the clickbox, shifter or cable, so replace those. Otherwise, the problem is internal.

Here are some information sources for rebuilds.

There are pages on this site about hubs which get little coverage elsewhere: the G8 8-speed and G9 9-speed hubs, the i-Motion 9-speed hub, the Elan, and the Orbit 2 x 6 (or 2 x 7) hybrid-gear hub.

SRAM keeps an excellent resource online. You can start with SRAM's technical page. The Product Manuals and Quick Starts listed on that page cover installation and adjustment of hubs.

If you are going to rebuild a hub, then you need to look at the Technical Manuals. The manual for each year is very similar except for the introduction of new models and deletion of discontinued ones. Some archived manuals are here but others have been moved to SRAM's Chinese site. The 1999 manual ( another source) (yet another source) (yet another) (auf Deutsch) (en français) is the only one online which covers the Elan/E12 and the 3 x 7. The 2015 spare parts manual covers the G8, G9 and DualDrive 3.

Aaron's Bicycle Repair also has technical information online about Sachs/SRAM hubs, including tips for practical assembly and disassembly.

Sutherland's Handbook of Internal-Gear and Coaster Brake Hubs, published in 1992 and now online on this site, has very complete information, including trouble charts and comparative parts lists, on Sachs two-speeds and the models 415, 515, H3102 and H3111 3-speeds. (Disclaimer: I was one of the authors!) The Third Edition of Sutherland's Handbook for Bicycle Mechanics, published in 1981, and Fourth Edition, published in 1985, cover most of these hubs. Many bicycle shops keep copies.

Karsten Stielow's site Karstilo.net covers many Sachs hubs from the 1960s onwards.. The text is in German but there are many exploded drawings and photos.

A reader of this site has sent us links to a photo guide to rebuilding the S7, along with some additional useful information -- in Russian.

SRAM S7 coaster brake overhaul, photo guide and illustrated article in Russian
SRAM S7 coaster brake vs. drum brake version: differences and interchangeability

Walter Jakuba, Das Zweirad -- has ample information on Sachs hubs from the 1950s through 1990s. The site is in German but the clickable links in the column at the right side lead to lists of hubs. Most of the exploded drawings and parts lists are in both German and English. They are best viewed if you right click (in Windows; or use a similar command on the Mac) and select "Only This Frame". Das Zweirad sells a considerable selection of spare parts for Sachs and SRAM hubs.

Jens Hansen's Scheunenfun (barn-find fun) site has information on many older Fichtel & Sachs hubs:: exploded drawings, parts lists and step-by-step rebuilding instructions, with photos. The text is in German, but the drawings should make the rebuilding process clear enough. Hansen sells replacement parts for older hubs, too.

Andree Schote's site also has information (in German) on older Fichtel & Sachs hubs.

Werbung:

Siehe auch

SRAM Corporate Site
SRAM Internal Gear Hub page
SRAM History Page
SRAM Technical Page
Sachs Elan 12-speed Hub
Sachs Orbit
SRAM G8 and G9
i-motion 9, 9-speed SRAM hub
Aaron's Bicycle Repair
Karstilo.net (in German; many drawings and photos)
Walter Jakuba, Das Zweirad
Jens Hansen's Scheunenfun (barn-find fun) site

Quelle

Dieser Artikel basiert auf dem Artikel Sachs and SRAM Internal-Gear Hubs von der Website Sheldon Browns. Originalautor des Artikels ist John Allen.

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