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Internal Gear Hubs
by Sheldon "Numbers" Brown
New! On-line Gear Calculator for Internally-Geared Hubs
| SRAM/Sachs | Shimano | Sturmey-Archer | ||
|---|---|---|---|---|
| 7-speed | 12-speed | 4-speed | 7-speed | 7-speed |
| Accessories | Bicycles | Parts | Specials | Tools |
|---|
| SRAM/Sachs | Shimano | Sturmey-Archer | ||
|---|---|---|---|---|
| 7-speed | 12-speed | 4-speed | 7-speed | 7-speed |
Since the turn of the century, internal-gear hubs, usually 3-speeds, have offered a practical, reliable gear shifting option to the cyclist. With the popularity of derailer gears taking off in the early 1970's bike boom, internal geared hubs went out of style in most markets. This is unfortunate, because many casual or utilitarian cyclists are best served by this type of gearing.Internal gear hubs are more reliable than derailer systems, and require much less maintenance. Unlike derailers, they may be shifted even when the bicycle is stopped, a valuable feature for the cyclist who rides in stop-and-go urban traffic. If you are interested in old bikes, or the history of this sort of gearing, refer to my page on English Three Speeds.
In the late 1990's, internal gears are undergoing something of a renaissance, with the development of wide range 7-speed hubs. There are currently 3 different brands of 7-speed hub available (although the Sturmey-Archer Sprinter has very limited distribution at present.) This page shows the gear ratios offered by each of the three. In addition, SRAM/Sachs offers a 12-speed hub.
The gear ratios provided are shown in the following charts. The numbers in the charts are equivalent sizes.
For example, if you use an 18 tooth sprocket on the Shimano 7-speed hub, 7th gear would give you the equivalent of an 11.7 tooth sprocket.
While the charts below only list sprockets from 18 to 22 teeth, these are not the only choices, and by selecting appropriate sized sprockets the overall range of any of these hubs can be raised or lowered any desired amount. All of the hubs shown here (except for the SRAM/Sachs 12 speed) take 3-splined sprockets, and they are all interchangeable. These sprockets are available from various sources from 13-22 teeth. It is also fairly easy to modify any Shimano cassette sprocket that doesn't have a built-in spacer. These are available from 14-34 teeth. Shimano cassette sprockets are the same diameter as those used with internal gear hubs, but have 9 sprockets instead of 3. With a suitable grinder, 6 of the splines need to be removed, and the corners of the remaining three rounded off. A thin spacer washer may also be needed, because the cassette sprockets are a bit thinner than the stock sprockets.
| 1st | 17.2% | 2nd | 13.8% | 3rd | 17.3% | 4th | 15.8% | 5th | 16.6% | 6th | 15.7% | 7th |
|---|
| Gear | Ratio | 18 Tooth | 19 Tooth | 20 Tooth | 21 Tooth | 22 Tooth |
|---|---|---|---|---|---|---|
| 7th | (1:1.545) | 11.7 | 12.3 | 12.9 | 13.6 | 14.2 |
| 6th | (1:1.335) | 13.5 | 14.2 | 15 | 15.7 | 16.5 |
| 5th | (1:1.145) | 15.7 | 16.6 | 17.5 | 18.3 | 19.2 |
| 4th | (1:0.989) | 18.2 | 19.2 | 20.2 | 21.2 | 22.2 |
| 3rd | (1:0.843) | 21.4 | 22.5 | 23.7 | 24.9 | 26.1 |
| 2nd | (1:0.741) | 24.3 | 25.6 | 27 | 28.3 | 29.7 |
| 1st | (1:0.632) | 28.5 | 30.1 | 31.6 | 33.2 | 34.8 |
| 1st | 14.0% | 2nd | 20.2% | 3rd | 22.9% | 4th | 22.7% | 5th | 20.3% | 6th | 14.1% | 7th |
|---|
| Gear | Ratio | 18 Tooth | 19 Tooth | 20 Tooth | 21 Tooth | 22 Tooth |
|---|---|---|---|---|---|---|
| 7th | (1:1.684) | 10.7 | 11.3 | 11.9 | 12.5 | 13.1 |
| 6th | (1:1.476) | 12.2 | 12.9 | 13.6 | 14.2 | 14.9 |
| 5th | (1:1.227) | 14.7 | 15.5 | 16.3 | 17.1 | 17.9 |
| 4th | (1:1.000) | 18 | 19 | 20 | 21 | 22 |
| 3rd | (1:0.814) | 22.1 | 23.3 | 42.5 | 25.8 | 27 |
| 2nd | (1:0.677) | 26.6 | 28 | 29.5 | 30.1 | 32.5 |
| 1st | (1:0.594) | 30.3 | 32 | 33.7 | 35.4 | 37 |
| 1st | 15.0% | 2nd | 15.9% | 3rd | 25.0% | 4th | 24.0% | 5th | 16.9% | 6th | 15.8% | 7th |
|---|
| Gear | Ratio | 18 Tooth | 19 Tooth | 20 Tooth | 21 Tooth | 22 Tooth |
|---|---|---|---|---|---|---|
| 7th | (1:1.68) | 10.7 | 11.3 | 11.9 | 12.5 | 13.1 |
| 6th | (1:1.45) | 12.4 | 13.1 | 13.8 | 14.5 | 15.2 |
| 5th | (1:1.24) | 14.5 | 15.3 | 16.1. | 16.9 | 17.7 |
| 4th | (1:1) | 18 | 19 | 20 | 21 | 22 |
| 3rd | (1:0.8) | 22.5 | 23.8 | 25 | 26.3 | 27.5 |
| 2nd | (1:0.69) | 26.1 | 27.5 | 29 | 30.4 | 31.9 |
| 1st | (1:0.60) | 30 | 31.7 | 33.3 | 35 | 36.7 |
| 1st | 24.0% | 2nd | 21.0% | 3rd | 22.7% | 4th |
|---|
| Gear | Ratio | 18 Tooth | 19 Tooth | 20 Tooth | 21 Tooth | 22 Tooth |
|---|---|---|---|---|---|---|
| 4th | (1:1.84) | 9.8 | 10.3 | 10.9 | 11.4 | 12 |
| 3rd | (1:1.50) | 12 | 12.7 | 13.3 | 14 | 14.7 |
| 2nd | (1:1.24) | 14.5 | 15.3 | 16.1 | 16.9 | 17.7 |
| 1st | (1:1) | 18 | 19 | 20 | 21 | 22 |
Note: This hub has been discontinued
and is no longer supported by the manufacturer.
| 1st | 23.1% | 2nd | 17.7% | 3rd | 18% | 4th | 12.7% | 5th | 12.0% | 6th | 8.0% | 7th |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 6th | 8.0% | 7th | 8.7% | 8th | 9.7% | 9th | 8.3% | 10th | 6.7% | 11th | 7.2% | 12th |
| Gear | Ratio | 26 Tooth |
|---|---|---|
| 12th | (1:2.38) | 10.9 |
| 11th | (1:2.22) | 11.7 |
| 10th | (1:2.08) | 12.5 |
| 9th | (1:1.92) | 13.5 |
| 8th | (1:1.75) | 14.9 |
| 7th | (1:1.61) | 16.1 |
| 6th | (1:1.49) | 17.4 |
| 5th | (1:1.33) | 19.5 |
| 4th | (1:1.18) | 22 |
| 3rd | (1:1) | 26 |
| 2nd | (1:0.85) | 30.6 |
| 1st | (1:0.69) | 37.7 |
A German company, Rohloff is preparing to come out with a 14-speed hub this spring. Information on their hub is available at the Rohloff Website
I purchased a Shimano SG-7R40 hub, and installed it on one of my own bicycles, an early '70's Peugeot PX-10 racing bike. While the jury is still out on the long-term durability of this hub, my initial impression on actually using one is extremely favorable. I particularly like the Rapid-Fire control unit, which is very easy to use and has a very light touch. I also am pleased at how well protected the linkage to the hub is. This hub uses a rotating ring operated by the cable, inboard of the chainstay. There are no delicate parts protruding out past the frame, as with other internal-gear hubs. I find the range of gears quite pleasant to use, and the efficiency of the hub doesn't appear to be any worse than the Sturmey-Archer FM four-speed unit it replaced.My Peugeot "PX-7" has time-trial style "cowhorn" bars, which are a lot like the bottom part of drop bars. The usual orientation for the Rapidfire shifter is on the right, hanging below straight bars, where it may easily be operated by the right thumb. The cable runs inward parallel to the bar.
On my Peugeot, I had it on the left side, clamped to the bar just below the brake lever, where it it very convenient to be operated by my left thumb. The cable runs downward, making a neat run toward the down tube of the frame. This works quite well for me. I have a separate page about this bike, with pictures.
Since I wrote that, I acquired a nice old Raleigh Competition frame, and have moved that wheel to this bike.
Thanks to Matt Dekker for providing the data on the Sturmey-Archer Sprinter.
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