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Beginner's Guide: Everything You Need to Know About Cassettes

by Martin Yang 26 Nov 2024
Beginner's Guide: Everything You Need to Know About Cassettes

Including gear ratio choices, materials utilized, and working details, this is all you need to know about bike cassettes.

Most contemporary bikes—road bikes, gravel bikes, and mountain bikes—have gears. Across a set of sprockets installed on the rear wheel hub, the rear derailleur moves your chain either up or down. Your cassette consists of those sprockets (or gears, or cogs—whatever you would want to name them).

Different riding needs call for different-sized cassettes. Usually, the smallest and biggest count of teeth on the gears indicates the size. A standard modern road bike cassette, for instance, might have 11–32 teeth. For mountain bikes, it might be something like 10–52 t.

This article will cover what a cassette is, how to determine its "speed," discuss the usual gear range for various kinds of riding, and highlight the main variations between budget and high-end cassettes, plus more.

 

What is a cassette?

▲ A cassette is an essential component of most bicycle drivetrains.

 

Though they seem basic, bike cassettes involve a lot of engineering.

The several sprockets in a cassette are meant to cooperate as a system, with each cog exactly placed to guarantee seamless chain transitions between gears, not merely a collection of gears.

Every sprocket has differently shaped teeth, and the sides usually feature ramps to assist with chain guidance during shifts. Over many years, these ramps have been tweaked to enhance shifting performance.

Shimano, for instance, employs a technology called Hyperglide to try to give a seamless shifting experience. Their most recent cassettes feature an upgraded form known as Hyperglide+, which Shimano says can improve shifting under heavy load and cut shift time by one-third relative to Hyperglide.

 

▲ A cassette usually needs to be replaced as a whole.

 

Other companies that make cassettes, like SRAM and Campagnolo, also use comparable designs meant to improve seamless shifting.

Cassettes are offered as a set instead of individual sprockets since they are intended as a complete system and typically need to be changed completely. Usually, it is impossible to simply replace one cog in a cassette with another since it might compromise the shifting performance.

 

What is the "speed" of my cassette?

▲ The Campagnolo Ekar gravel groupset comes with a 13-speed cassette and a 9-tooth sprocket.

 

Usually, a cassette features between seven and thirteen sprockets.

Particularly on high-end road bikes, 12-speed drivetrains are becoming widespread nowadays. Shimano followed suit in 2021 with the debut of their Dura-Ace Di2 R9200 groupset, following SRAM and Campagnolo into the 12-speed market.

Usually teamed with a single chainring, 12-speed cassettes have essentially become the standard for mid- to high-end configurations for mountain bikes.

The speed rating of the other components must match the sprockets on a cassette. This is so because most shifting systems operate by moving the derailleur a defined distance for every click, so a changing number of sprockets will not cause them to function as intended. More sprockets indicate smaller gear spacing, and the chain width must likewise fit the cassette.

Generally speaking, lower-tier groupsets have fewer gears; hence their cassettes also have fewer sprockets. There are several exceptions, though. For example, SRAM's X01 DH and GX DH downhill groupsets employ a 7-speed cassette running with an 11-speed chain. For bikes without climbing capability, the reduced number of gears helps create closer ratios between each gear and permits a shorter derailleur cage, hence optimizing ground clearance.

 

Gear Ratio

 

Apart from the sprockets count, a major determinant of compatibility with your powertrain is the range of accessible teeth on a cassette.

Usually for the smallest cog, cassettes begin with 10, 11, or 12 teeth. There are significant outlays, though, such as those with 9, 13, or even 14 teeth as the smallest cog.

Sometimes brands show their cassettes together with a gear range %.

For instance, the 520% gear range of SRAM's 10-52t cassette—how did SRAM arrive at that figure? And how might you figure your gear range percentage?

The lowest cog is 10 teeth, and the largest is 52 teeth; hence, 52, equivalent to 520% of 10, is obtained. The gear range is 520%.

 

▲ SRAM Eagle offers an oversized 52-tooth sprocket on certain cassette models.

 

It is noteworthy that this figure just shows the gear range of the cassette. With that gear range, your riding distance will not rise in the same proportion.

Likewise, it doesn't indicate whether your manner of riding would fit it. For that, you would have to figure the real gear ratio—a completely different subject.

 

Road Bike Cassette

▲ The 11-28 cassette used to be considered a wide-ratio training cassette, but now it's on the smaller end of the standard range for road bikes.

 

Road bike cassettes have been growing ever larger in recent times.

An 11-28 cassette was regarded as a "light" training configuration a few years back, but today the smallest choice offered on the Shimano Dura-Ace R9200 is 11-28. Although that may not sound significant, the way pro riders employed 11-23 or 11-25 cassettes reveals a rather different picture.

The main cause of this change is the rise in cassette speed count.

With 12-speed road groupsets, cassettes now have a larger range while maintaining a rather tiny gear difference. For instance, whilst on the larger end of the cassette the jumps are larger, on the smaller end each shift might just be one tooth apart. Should you have a 7-speed or 8-speed cassette with the same range, the gear interval would be considerably more pronounced.

Another consideration is the changing attitude regarding moving. Not recognized as a badge of honor anymore is grinding away at low cadence to "muscle" through gears—something our knees most definitely appreciate!

 

▲ The R9200 offers 12 speeds and a larger cassette than before.

 

When switching to 12-speed, Shimano and Campagnolo stayed with their current gear ratios and added an extra sprocket to offset the greater leaps in the larger speeds. Every change feels a little more fluid and close-knit as a result. Conversely, SRAM followed a different path, which we will discuss in a bit.

You have 11-28, 11-30, and 11-34 choices with Shimano's most recent R9200 groupsets. These ratios were also available in their 11-speed configurations; however, the Dura-Ace R9100 lacked an 11-34 choice.

Conversely, Campagnolo provides the largest cassette in their 11-speed lineup—an 11-29 choice across all their 12-speed groupsets.

Now, nevertheless, the Italian brand offers everyone with an 11-32 cassette choice. Additionally available at the Chorus level and limited to the Chorus rear derailleur is an 11-34 cassette.

▲ SRAM's road bike cassettes have taken a different direction.

 

Mountain Bike Cassette

 

▲ Shimano offers two cassette options for their mountain bike groupsets.
 

Mostly because 1x drivetrains have become more common, mountain bike cassettes have also gotten bigger. One-x configurations lack a tiny chainring to assist in climbing; hence, the cassette must have a larger range to provide riders with appropriate gears for climbing.

Mountain bike cassette choices are sometimes less plentiful than road bike options.

Only two cassette sizes—10-45 (not available at the Deore level) and 10-51—are included in Shimano's 12-speed portfolio. While the 10-45 can run with both 1x and 2x configurations, the 10-51 cassette is for 1x systems only.

 

▲ A few years ago, large cassettes like the 10-50 found in SRAM’s Eagle groupset were not common.

 

Two other cassette sizes for SRAM's Eagle series are 10-50 and 10-52. Offering both of the big brands, the 10-52 is the biggest gear selection available. Although there are two choices right now, the 10-50 could progressively be taken out over time as the 10-52 is now the new benchmark.

Make sure your derailleur is suitable if you wish to use the 10-52 option; prior model Eagle mechanical derailleurs had rather shorter cages.

SRAM provides an 11-50 cassette for users of their entry-level Eagle groupsets, SX Eagle and NX Eagle. Since the 10t cogs need an XD driver, the cassette can thus be placed on a conventional Shimano HG freehub—which we shall discuss in more depth later.

 

▲ The new SRAM T-Type groupset only supports a 10-52t cassette.

 

SRAM later released their new derailleur, completely eliminating the derailleur hanger. The derailleur no longer has limit or B-tension screws, making it compatible only with a 10-52t cassette.

 

Gravel Bike Cassette

▲ All major drivetrain manufacturers have introduced gravel-specific products.

 

Gravel bikes are best considered as a blend of mountain bikes and road cycles. Therefore, it is rather common to see them suited with either road or mountain cassettes.

However, there are now gravel-specific cassette choices available as groupset manufacturers adopt the gravel riding trend.

The XPLR AXS groupings from SRAM are especially meant for gravel cycling. The XPLR cassette calls for a suitable derailleur and offers a 10-44 range. Mix drop-bar shifters with the mountain bike Eagle eTap AXS groupset if you want a super-wide range 1x configuration. SRAM names this the "mullet" arrangement.

Additionally possible is mixing the XPLR AXS shifters and crankset with the new Transmission drivetrain system.

 

▲ The new SRAM Red XPLR AXS groupset is different from others in that it uses a rear derailleur that mounts directly onto the rear axle.

 

The latest SRAM Red XPLR AXS groupset stands out because it relies on a rear derailleur that mounts directly to the rear axle, similar to the Transmission mountain bike groupset. Unlike all other SRAM cassettes, it's a 13-speed setup and uses a 10-46t gear range.

 

▲ Campagnolo's gravel groupset is 13-speed.

 

Another brand creating a 13-speed groupset especially for gravel is Campagnolo. With a lowest cog of just 9 teeth, the Campagnolo Ekar 13-speed gravel groupset presents choices of 9-36, 9-42, or 10-44. Ekar is a committed 1x system.

The lower-tier Campagnolo Ekar GT groupset is also 1x but comes with a 10-48t cassette option.

The 12-speed 1x drivetrain provides cassettes in 10-45 and 10-51t for Shimano GRX users; the 2x arrangement provides 11-34 or 11-36t.

Shimano's own 11-speed road or mountain cassette allows you options for the original 11-speed model. While the mountain bike choices run 11-40, 11-42, or 11-46, road cassettes range from 11-34. Though Shimano's range seems more constrained than that of its rivals, take in mind that GRX is a gravel groupings set compatible with 1x and 2x systems.

 

Cassette Compatibility Guide

▲ DT Swiss wheels with HG freehub bodies support Shimano/SRAM cassettes.

 

Freehub Compatibility

The freehub features splines interacting with the grooves on the freewheel. These splines guarantee that the freewheel cogs stay relative and in the correct orientation, so enabling the whole shifting mechanism to run as it should.

Every drivetrain manufacturer has its unique freehub design; hence, not every cassette fits every wheel set (or powertrain).

 

Shimano freehub

 

The Shimano HG freehub design has been the most common choice for years.

 

Comprising nine splines, Shimano's 11-speed HG freehub is the most often used technology. Almost all Shimano groupsets applied this freehub architecture before 11-speed. Though there were occasional exceptions, like SRAM's 1x11 mountain bike groupset, before their 12-speed groupsets, SRAM also employed the same freehub design.

Shimano unveiled a fresh freehub design for its road bike groupsets when Ultegra and Dura-Ace switched to 12-speed. Still, 12-speed Shimano cassettes are perfectly compatible with 11-speed freehubs.

Shimano matched a new freehub standard dubbed Microspline with their 12-speed Deore, SLX, XT, and XTR groupsets for mountain bikes.

Should you be using a Shimano HG freehub, you should take note of the width of the purchased cassette. By 1.85 mm, road bike freehubs are somewhat broader than mountain bike freehubs; 11-speed Shimano HG road cassettes are thus somewhat wider than 8-speed or 9-speed cassettes. 

While you cannot put road cassettes on a mountain bike hub, you can add a 1.85mm spacer to install cassettes with fewer speeds, including mountain or road cassettes, if you are using an 11-speed road hub. To fit 10-speed road cassettes, which are thinner than 8-speed or 9-speed cassettes, you will need to use a 1.85mm spacer and another 1mm spacer.

 

Campagnolo Freehub

 

▲The N3W freehub is a shortened version of Campagnolo's existing road freehub design.

 

Different from Shimano and SRAM, Campagnolo also has a proprietary freehub standard that is incompatible with any product from the two rivals.

To fit its 13-speed Ekar cassette, the brand has also unveiled a new freehub standard known as N3W. Additionally enabling the use of this standard with Campagnolo's earlier standard cassettes is the conversion hub for it.

 

SRAM Freehub

 

▲SRAM's XD freehub body

 

When SRAM debuted cassettes with a 10-tooth minimum gearing, it presented its XD hub standard. With the XDR standard, SRAM recently modified this design for road bikes such that they may use a 10-tooth cog; however, it is rather wider than the usual road bike standard.

SRAM's XDR road hub indeed is 1.85mm wider than the XD MTB hub. You can install an XD cassette on a wheelset with an XDR hub by using spacers, but you cannot install an XDR cassette on an XD hub.

 

Mountain Bike Cassette vs Road Bike Cassette

Some might think about riding a mountain bike using a road cycle cassette or vice versa. Here we will go over why you would choose to (or might not wish to) do this and consider the possible compatibility problems resulting from these decisions.

Because conventional road cassettes have a far smaller gear range than mountain bike cassettes, most people do not put road bike cassettes on mountain bikes. While still having low enough ratios for downhill sections, mountain biking sometimes calls for a larger gear range to negotiate steep hills.

 

Unless you're using a triple chainring setup, you're unlikely to want to use a road bike cassette on a mountain bike.

 

A road bike cassette might provide a broad enough gear range if you still use a triple chainring configuration, but this is becoming a fairly "old-school" decision. Consider using a mountain bike cassette on a road bike if you're looking for a simpler climbing arrangement or if you're getting ready for a lengthy ride. You should be sure, though, that your hub and derailleur fit the bigger gear ranges of mountain bike cassettes.

The range of cogs the derailleur's guide plate can accommodate is usually restricted by its design. Shimano's Dura-Ace R9100-SS, for instance, is meant to support a maximum 11-30 cassette. This makes it incompatible with an 11-34 cassette since, when riding on the biggest cogs, the guide plate is too short to sustain enough chain tension. Furthermore, long enough to fit the bigger 34t cog is the chain length.

Should you wish to convert to an 11-34 cassette, you will also need to purchase a suitable derailleur alongside the cassette. Shimano's Ultegra R8050-GS or 105 R7000-GS, for instance, are "medium cage" models that fit bigger cassettes. Shimano's Di2 groups have the same naming scheme.

 

If you want to use an 11-34t cassette on a road bike, you'll need a long cage derailleur.

 

 

Running an 11-34 cassette calls for more than simply selecting the correct cassette; you also have to ensure your derailleur is suitable. Shimano's Ultegra R8050-GS, for instance, or 105 R7000-GS, fit perfectly. For those bigger cogs, the "GS" denotes long cage derailleurs—what you will need. Shimano's Di2 configurations follow the same name convention as well.

Running an SRAM AXS derailleur will normally show "Max 33t" and handle up to a 33t cassette for road bikes. Additionally available for matching a 10-36 cassette is a "Max 36t" option. Using the Red XPLR AXS, SRAM's XPLR derailleur can manage cassettes up to 44t, or even 10-46t.

Other than the Chorus, which can accept an 11-34t cassette, Campagnolo's 12-speed derailleurs top out at an 11-32t.

Remember too that your chain should be long enough to manage any larger gear range you are switching to.

 

Cassette Materials: Steel vs Aluminum vs Titanium

▲The Shimano Dura-Ace R9200 features a carbon fiber "spider" to reduce weight.

 

Usually composed of robust yet hefty stamped steel, the least expensive cassettes are Usually, better materials and more polished surface treatments follow from a rising price.

For instance, five of the twelve cogs on Shimano's premium Dura-Ace R9200 cassette are titanium alloy cogged. Since the smaller cogs have fewer points of contact with the chain and softer materials wear out more quickly, they nevertheless need steel.

By means of a single-piece CNC machining technique, SRAM reduces the weight of their high-end Red AXS 12-speed cassette by eliminating extraneous material. Lightweight aluminum alloy cassettes from Rotor and Miche also fit with standard road bike systems.

 

▲Rotor and Miche also produce cassettes compatible with mainstream groupsets, although the 13-speed Rotor 1x13 cassette shown in the image is only compatible with Rotor's own groupset.

 

Usually paired together, the bigger cogs are supported by a single carrier—or "spider"—that meshes with the freehub body. Since these cogs don't come into direct contact with the chain, the carrier can be built from smaller components and helps reduce weight. The Dura-Ace cassette, for example, makes use of a carbon fiber carrier.

While some cassettes feature individual cogs, mid-range cogs are often separated by alloy- or occasionally plastic spacers. Typically, the smaller cogs include built-in spacers.

Part of the cassette assembly, most cassettes—except for SRAM XD and XDR—are fastened onto the freehub body using a lockring. Though aluminum alloy is a lighter substitute, steel is the usual material used in lockrings.

 

Cassette Prices: What Are You Paying For?

▲SRAM's Red cassette is made from a single piece of metal through machining.

 

High-end cassettes can cost a lot of money; some of the most costly ones today run over £300. What then precisely are you getting for the money?

Usually composed of special materials like titanium or carbon fiber, which are used for particular cogs and their carriers, higher-end cassettes are For instance, the SRAM Red road cassette is CNC-machined from a single piece of metal. Generally speaking, more upscale cassettes are lighter and more finely built than less expensive choices.

On performance, meanwhile, the Dura-Ace 11-28 cassette and those discovered in Shimano Ultegra or 105 groupsets are not significantly different; therefore, choosing a lower-spec cassette will help you to save a lot of money.

Similar choices abound for SRAM, which now provides an entry-level 12-speed cassette, a more reasonably priced substitute for the Red and Force cassettes with the advent of the Rival eTap AXS. The same reasoning holds true for mountain bike groups from SRAM.

Remember that cassettes are wear-and-tear objects that must be replaced often. You may project the lifetime of your cassette by usually replacing your chain when it shows 0.5% elongation (for 11/12/13-speed) or 0.75% (for 10-speed and less). A cassette will often run through three chains. Still, how fast it wears down will rely on your local riding circumstances and chain maintenance.

As the chain elongates, the cassette will likewise suffer more wear if you keep riding with high intensity. Replacing high-end cassettes can be costly; hence, it's advisable to be very careful with maintenance to prevent unneeded expenses.

 

Recommended Reading:

  1. A Comprehensive Guide to Rear Derailleurs
  2. Super Boost Plus 157 Rear Axle Standard: Is It Here to Stay?
  3. Beginner's Guide: How to Find the Optimal Tire Pressure for a Road Bike
  4. Is the Single Chainring Drivetrain the New Trend for Road Bikes?
  5. Cycling Posture Guide
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