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There are also articles on this site more generally about internal-gear hubs
and about the Sachs Elan 12-speed hub,
the Orbit hybrid gearing system
and the i-Motion 9 9-speed hub.
We have links to technical information on most other Sachs/SRAM hubs.
Sheldon Brown's Internal-Gear Calculator
The German company Fichtel & Sachs, often called only "Sachs", has been manufacturing internal-gear hubs longer than any other except Sturmey-Archer. In 1997, the American company SRAM acquired Fichtel & Sachs, and so current products carry the SRAM name.
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 5-speed and 7-speed models and hybrid gearing systems -- first the Orbit, a two-speed hub with proprietary sprockets, then the 3 x 7, 3 x 8 and 3 x 9 systems 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. In 1995, Sachs introduced 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 It has been withdrawn, and now SRAM offers an 8-speed hub, the G8.
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 resulting from the quality of the machining.
Sachs/SRAM internal-gear hubs are quite rugged, like classic Sturmey-Archer hubs. The mechanical design of most hubs is relatively simple and conservative. 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. Starting with the 9-speed hub, SRAM abandoned the "clickbox" for a rotary-shifting 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 front-indexing STI shifter also works with a Sachs hub -- my Bike Friday has a matched set of Shimano RSX STI brifters shifting its 3 x 7 system, 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 are generally available only with twist shifters that fit flat handlebars. SRAM's assumption seems to be 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 reporteded 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 3 x 8, 3 x 9 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 recently-introduced (and since discontinued) i-Motion 9-speed hub has been described as a "cannonball" because of its size and weight! A version with a carbon fiber shell has been marketed, but the weight of the internal parts still is substantial. We now have detailed information on this hub.
We have only this information on installation of the G8 8-speed hub as of yet.
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 i-Motion 9, 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 be lubricated through one of the disk-brake bolt holes at the left side). Oil is preferable for its lower rolling resistance, and because it can be replenished without disassembling the hub. Caution also is in order not to use 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.
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.
Though the 3 x 7 has only as 7-speed cassette body, I prefer the 3 x 7 over the more recent DualDrive models because it has pullchain shifting, no vulnerable clickbox, and is compatible with a 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 more 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 sprockets on a 7-speed body here. 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 provided this modification on its bicycles.
The S7 7-speed hub can be set up for an overall range from 27 through 82 gear inches. 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 hubs or I wouldn't be using them.
The G8 looks promising for urban use, but I don't have hands-on experience with it yet.
Harris Cyclery sells Sachs/SRAM internal-gear hubs but does not specialize in them, largely because SRAM does not provide much product support for them in the USA. Aaron's Bicycle Repair in Seattle, Washington, USA specializes in repair of internal-gear hubs and stocks parts for SRAM hubs including discontinued models.
Aside from Aaron's? I needed two internal parts for a 3 x 9 DualDrive hub. Harris Cyclery was unable to order them through SRAM in the USA. Bike Friday installs DualDrive hubs on many of the small-wheel bicycles it manufactures, 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.
I finally got the idea to contact 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.
The axle threading of most SRAM internal-gear hubs is close enough to that of classic Sturmey-Archer hubs that axle nuts are interchangeable in a pinch. This compatibility can be useful, especially if you need to replace the flared nut through which the pullchain runs. The i-Motion 9 and G8 use common 10 x 1mm threaded axle nuts.
My intention here is to provide the best information I can on rebuilding Sachs/SRAM hubs.
If you live in the USA, 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.
If a DualDrive hub or other three-speed with a pullroad, 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 if the hub is in low gear (the wheel turns much 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.
These 3-speed hubs use a pullrod, but 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.
Here are some information sources for rebuilds of the internals, going from the newest to the oldest hubs:
SRAM keeps an excellent resource online, including technical manuals for most current and recently discontinued hubs. 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. Archived manuals are here. The 1999 manual is the only one online which covers the Elan/E12 and the 3 x 7.
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, 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.
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 identify each hub by the model name and number. 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 bike 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.
|SRAM Corporate Site|
|SRAM Internal Gear Hub page|
|SRAM History Page|
|SRAM Technical Page|
|Sachs Elan 12-speed Hub|
|i-motion 9, 9-speed SRAM hub|
|SRAM hubs on sale at Harris Cyclery|
|Aaron's Bicycle Repair|
|Karstilo.net (in German; many drawings and photos)|
|Articles by Sheldon Brown and others|
Last Updated: by Harriet Fell