What are Shimano's SS and GS rear derailleurs?

Some Shimano Rear Derailleurs Come in Two Versions

Depending on the model, Shimano rear derailleurs are available in two cage lengths: SS (short cage) and GS (medium cage). The “cage” here refers to the pulley cage, which houses the two jockey wheels and varies in length.

In the example shown above, both derailleurs are from the Shimano 105 series (RD-R7000), but the SS version (left) and the GS version (right) have visibly different pulley cage lengths.

From a technical perspective, the difference between SS and GS lies in:

• Max/min number of teeth on the low/top sprockets
• Chainring tooth difference
• Total drivetrain capacity

But to keep it simple:

• SS (Short Cage) is for narrow-range (close-ratio) road cassettes
• GS (Medium Cage) is for wide-range cassettes

Gear Ratios: Cross, Wide, and the Deep World

Cross ratios, wide ratios, the world of gear ratios is a deep one. We will take a look at the advantages and disadvantages of changing the number of teeth on the sprocket, and the combination with the chainring.

However, just because GS supports a larger cassette doesn’t mean “bigger is always better.”

Let’s compare the GS and SS versions of Shimano’s race-ready 105 rear derailleur, RD-R7000:

Pay special attention to the “Min Low Sprocket” and “Max Top Sprocket” values.

The GS version requires at least a 28T low sprocket, meaning it’s not compatible with tighter cassettes like 11-25T. Also, since its max top sprocket is 12T, it won’t support cassettes like 14-28T which are geared for lighter setups.

GS and SS Specs Can Differ by Product

Even within Shimano’s lineup, GS or SS doesn’t always mean the same specs across different series.

For example, if we compare the entry-level CLARIS RD-R2000-SS with the mid-range 105 RD-R7000-SS, we can see notable differences in their specifications:

The RD-R2000-SS supports a wider range cassette (11-32T) compared to the RD-R7000-SS (11-30T). Interestingly, the GS version of the RD-R7000 we looked at earlier has a max low sprocket of 34T, which is only two teeth more than the RD-R2000-SS.

Compatible Cassettes Differ by Model

As shown in the previous table, even within the SS series, CLARIS allows for larger low sprockets (easier gears), enabling it to use wider-ratio cassettes. However, since CLARIS is an 8-speed system, the gear steps between each shift are large, which can feel jerky during shifting.

On the other hand, the 105 series supports 11-speed setups, meaning that even if you use a wide-ratio cassette, the gaps between gears are smaller, allowing for smoother shifting. Also, since the 105 allows for smaller low sprockets and larger top sprockets, it can support extremely narrow-ratio (close-ratio) cassettes like 14T-25T.

CLARIS can also support a close-ratio setup like 13T-25T, but the 11-speed 105 with a 14T-25T setup provides even finer gear steps, making it more optimized for performance.

Modern 12-Speed Components Don’t Use GS/SS Labels

Starting in 2021, Shimano’s latest road components such as DURA-ACE R9200, ULTEGRA R8100, and in 2022, 105 R7100 moved to a 12-speed system, and no longer distinguish rear derailleurs as GS or SS.

This is likely because the 12-speed cassettes range between 28T and 34T for the largest cog, which fits the capacity that used to require GS models. As a result, there’s no need for separate cage lengths.

So, when choosing a 12-speed rear derailleur for road use, you no longer need to worry about whether it’s GS or SS.

How Can I Tell If My Rear Derailleur Is SS or GS?

With recent Shimano models, there’s often no clear model number marking that indicates whether it’s SS or GS, making it harder to identify at a glance.

Here are two key ways to tell:

1. Pulley cage length (GS has about 3–4 cm more distance between the pulleys)
2. Pulley cage shape (GS cages are more curved than SS)

While the difference in cage length can be subtle, a simple rule of thumb is:

If there’s enough room between the pulleys to fit another pulley wheel (around 3–4 cm), it’s GS. If not, it’s SS.

Also, GS cages tend to have a sharper curve compared to SS. While this may be hard to notice without direct comparison, checking both the cage length and shape together should help you identify the type.

Which Should You Choose: GS or SS?

The choice between GS and SS primarily depends on the gear ratio setup you want to achieve. If you’re aiming for a close-ratio (tight spacing) cassette, go with SS. If you prefer a wide-ratio (bigger range) cassette, then GS is usually the better choice.

In the past, SS was standard for road bikes, and GS was typical for mountain bikes (MTB). However, recent trends have seen a shift toward wider-range rear cassettes, and GS is becoming more common for both road and MTB bikes.

Furthermore, modern MTBs now often use an even longer cage type called “SGS”, and some models no longer distinguish between SS and GS at all.

If You’re Replacing a Stock Cassette, Always Check If You Have GS or SS

One thing to be careful about: if you’re swapping out the cassette on a bike that comes with a stock rear derailleur, you must first check whether it’s compatible with the new cassette’s tooth count.

Even if an incompatible derailleur and cassette combination seems to “work,” issues can arise. The pulley cage length might not be appropriate, leading to interference with the sprockets on either end (low or high), or excessive chain tension. This could snap the chain or damage the frame in the worst-case scenario.

Also, if the low sprocket tooth count changes significantly, you may need to adjust the chain length and fine-tune the B-tension screw on the derailleur. For beginners, it’s best to consult a bike shop for such upgrades.

So far, we’ve taken a closer look at the SS and GS rear derailleurs from Shimano.

Once you become more comfortable with road cycling, you may want to switch to different cassettes for different riding conditions, or upgrade your cassette for a smoother ride. When doing so, be sure to check the model number of your rear derailleur and confirm which cassettes are compatible with it.

Frequently Asked Questions About Shimano Rear Derailleur SS and GS Types