What to know when buying a groupset

Content sponsored by Chain Reaction Cycles. Find out more about our sponsored content policies here. THINKING OF BUYING A NEW GROUPSET? There are many reasons for considering a new groupset, but the promise of an upgrade in performance is perhaps the most alluring. While the differences between…

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Content sponsored by Chain Reaction Cycles. Find out more about our sponsored content policies here.


There are many reasons for considering a new groupset, but the promise of an upgrade in performance is perhaps the most alluring. While the differences between entry-level and high-end groupsets are typically a matter of nuance, riders can expect lighter, crisper, and more precise gear shifting along with smoother and more powerful braking when spending more money on the components.

At the same time, buyers will save a bit of weight when upgrading. Shimano’s 11-speed Dura-Ace groupset is 500g lighter than the 105 equivalent, while Dura-Ace Di2 is almost 400g lighter than Ultegra Di2. Those weights savings won’t have a huge effect on the final weight of the bike (just 5-10%), but when combined with the difference in performance, few buyers ever regret spending the money on a new groupset.

Another good reason for replacing a groupset is to keep up with progress within the industry. In recent years, road groupsets have evolved from 10- to 11-speed transmissions and there has been the introduction of electronics and powered derailleurs. In fact, the rate of innovation has increased over the last couple of decades such that a groupset can become “outdated” in the space of 5-7 years now (that’s not to say it will stop working, but finding replacement parts will get more difficult).



Most bike frames will outlive the life of a groupset, especially if the owner races and/or clocks up big distances (>20,000km) every year. Harsh weather and/or riding conditions will also reduce the lifespan of a groupset. Whatever the cause, there will always come a time when the components start to exhibit significant wear and tear, both in terms of cosmetic and functional damage. At this point, a new groupset can do a lot to resurrect an otherwise tired and aging bike.

It’s also worth pointing out that there are times when the maintenance costs for an aging groupset can approach the expense of new groupset. For instance, the cost of replacing all of the consumable parts of a groupset — chainrings, chain, cassette, jockey wheels, and cables — can amount to half the cost of a new entry- or mid-level groupset. When combined with advances in the industry, there can be more value in replacing a groupset rather than overhauling it.

Of course, some cyclists will use the physical, functional and/or technological demise of their current groupset as an opportunity to replace the entire bike. For those that cannot afford this extravagance, a groupset can be replaced at a fraction of the cost of a new bike.

Replacing a groupset requires a major overhaul for the bike so shoppers should remember to budget for installation. At face value, a couple hours of a professional mechanic’s time might seem exorbitant, especially for an entry-level groupset, but if the new groupset is installed as part of an annual overhaul for the bike, then the extra expense remains relatively small in terms of the annual running costs of the bike.


There was a time when a groupset comprised up to a dozen components, however that definition has changed in recent years. Where once a headset, seatpost, and front and rear hubs were included in groupsets, now the collection of components typically provides the gear and braking systems for a bike.


Thus, a typical groupset comprises the brake/shifter levers, a cranksetfront and rear derailleursbrake callipers, a bottom bracketchaincassette, and all cables to suit the brake and gear system.

That list of components can vary though, due mainly to the growing diversity in road groupsets:

– Electronic groupsets include at least one battery and a charger along with all necessary wires and junction boxes, however accessory shifters for climbing or sprinting are typically optional;
– 1x transmissions don’t include a front derailleur or a left-hand shifter, though there will be a left-hand brake lever;
– Road disc groupsets are normally supplied with rotors for the disc callipers.

Shoppers need to be aware that there is much more to know about a groupset than just the list of components. Each component must be carefully selected from a number of options so that it matches the frame, wheels and the rider’s needs. Such variety in groupset specifications can overwhelm the uninitiated, but it gets easier by concentrating on one part at a time.


There are a few reasons for the range of specifications for a groupset. Some exist to accommodate different frame designs, others relate to options for the gearing of the bike, and then there is the matter of fitting parts like the cranks to different sized riders.

Unfortunately, there isn’t a lot of standardisation within the bike industry, and while this promotes innovation, it results in a variety of fittings and, inevitably, incompatibilities. At the same time, some fittings/options fail to find widespread favour such that one or more groupset manufacturers ignore them altogether.

Here are just a few examples:

– A buyer has just bought a new cutting-edge aero road bike frameset that has direct-mount brake callipers and wants to fit SRAM’s Red eTap groupset only to discover that the company doesn’t make a compatible brakeset;
– After several seasons of racing with a 10-speed transmission, the owner decides to upgrade to 11-speed then discovers he can’t use his carbon race wheels because of the 10-speed freehub body that can’t be upgraded;
– A shopper discovers a Dura-Ace groupset on sale but after delivering the bike and new groupset to his mechanic, is informed that he needs to speed more money on adaptors for the front derailleur and crankset before they can be fitted to the bike.

Contending with any of these issues ultimately falls to the consumer. While there are a number of aftermarket products to help with some incompatibilities, buyers really need to understand the difference between all the various specifications when shopping for a groupset.

Here is an overview of the specifications for current road groupsets:


Road shifters are integrated with the brake levers and dictate the gearing options for the groupset.

Left lever: Single, double, or triple shifting.
Right lever: 8-, 9-, 10-, or 11-speed.


There are two types of front derailleur fittings:

Braze-on, which attaches to a tab on the seatpost.
Clamp-on, which has a clamp that wraps around the seat tube. The clamp must match the seat tube diameter of the frame, and there are three possibilities: 28.6mm31.8mm34.9mm.

Note: A braze-on front derailleur can be fitted to a frame without the tab via an adapter clamp to suit 28.6mm, 31.8mm, 34.9mm diameter seat tubes.


The rear derailleur can have one of three different cage lengths for the jockey wheels. The longer the cage, the larger the maximum rear cog size.

Short: Suits a maximum rear cog size of 28T.
Medium: Suits a maximum rear cog size of 32T.
Long: Suits a maximum cog size of 42T.

Note: Short and medium cage derailleurs are used with double cranksets while a long cage rear derailleur is necessary for a triple crankset.


There are three broad types of cranks that differ according to the number of chainrings attached, namely singledouble, and triple.
Crank arm lengths start at 165mm and are available in 2.5-5mm increments up to 180mm, depending on the manufacturer and the level of the groupset.

Note: Each manufacturer makes use of different crank axles: Shimano uses a single type of axle that is 24mm in diameter; Campagnolo has three types (Ultra Torque, Power Torque, and Over-Torque); and SRAM makes use of two (GXP and BB30).


Buyers normally get a few choices for the size of the chainrings that are fitted to the cranks:

Single: 38-54T in 2T increments.
Double: 53/39T, 52/36T, 50/34T.
Triple: 50/39/30T.


The bottom bracket provides the bearings for the cranks and must suit both the frame and the cranks. There is a lot of diversity in both, though they fall into one of two broad types, threaded or threadless.

Threaded: BSA, ITA, T47.
Threadless: BB86, BB92, BB30, BB30A, PF30, BB386, BBright.

Note: The amount of support for the various formats varies between manufacturers. An aftermarket conversion/adapter bottom bracket may be required for some crank and frame combinations.


The number of cogs in the cassette must match the shifters in groupset (i.e. 8/9/10/11). Buyers normally get a choice for the range in cog sizes, which are specified according to the size of the smallest and largest cogs. Common ranges include 11-23, 11-25, and 11-28.

Note 1: Shimano and SRAM 11-speed cassettes are wider than 8/9/10-speed cassettes and require a rear wheel with a wider 11-speed freehub body.

Note 2: Campagnolo cassettes utilise a proprietary design requiring a Campagnolo-specific freehub body for the rear wheel.


The chain must match the cassette, so an 8-speed cassette must be paired with an 8-speed chain. Thus, there are four major types of chain, 8-, 9-, 10-, and 11-speed.

Note: Shimano and SRAM chains and cassettes are interchangeable; Campagnolo are not.


There are just two types of brake levers, mechanical and hydraulic, where the latter is most commonly used for disc brakes.


There are two kinds of brake callipers: rim or disc. The choice of fittings is determined by the design of the frame and forks.

Rim brakes: There are two major fittings, single-bolt centre-mount and dual-bolt direct-mount.
Disc brakes: Also two major fittings, post-mount and flat-mount. In both instances, the disc callipers are paired with either 140mm or 160mm rotors, as dictated by the design of the frame and forks.


Most shoppers can use their existing groupset to guide their decisions on each part of the groupset in concert with the specifications for the bike from the manufacturer’s website or catalogue. The former is important for deciding aspects such as crank length and gearing, while the latter will guide the choice of brake callipers, crank axle and/or bottom bracket, and the type of front derailleur.

Not all of this information is readily available or easy for uninitiated to find, so for those that have any doubts, they should arrange to have the bike inspected by an experienced mechanic. It’s also worthwhile discussing the options for each component so that any potential incompatibilities can be identified before a purchase is made.


At present, three major manufacturers — Shimano, Campagnolo and SRAM — offer road groupsets at a range of pricepoints with a variety of technologies. Brand loyalty can be strong amongst experienced riders, providing plenty of powder for igniting coffee-shop debates. But in practical terms, all groupsets from these manufacturers provide reliable shifting and braking.

Indeed, the distinctions that separate one brand from the other are really a matter of nuance, such as the mode of shifter operation, ergonomics of the brake/shifter levers, the range of options and fittings, and the choice of finishes. In many instances, any brand can be used to build a road bike, however the suitability of any given groupset ultimately depends upon the frameset in question.

For those shoppers on a tight budget, Shimano’s groupsets are generally the most affordable and provide perhaps the widest range of options and fittings, however it does vary according to the level of groupset. For example, buyers hoping to use a triple crankset will not find this option for Shimano’s 11-speed groupsets; likewise, the lowest gearing that can be achieved for Dura-Ace groupset is 34 x 28T (or 34 x 30T for the just-released 9100 groupset).

The careful clustering of options and fittings also applies to the other brands, so while the list of options discussed above is seemingly large, it narrows considerably once a shopper focuses on a specific brand and/or level of groupset.

Overall, the range of groupsets from Shimano, Campagnolo and SRAM are pretty evenly matched in terms of price, options and technology. The latter makes for a constantly evolving landscape where shoppers must choose between paying top dollar for the newest technology or waiting for it to trickle down to more affordable products.



Shimano: 6 mechanical, 2 electronic.
Campagnolo: 6 mechanical, 3 electronic.
SRAM: 4 mechanical, 1 electronic.


Shimano: Braze-on, Clamp (28.6/31.8/34.9mm).
Campagnolo: Braze-on, Clamp (31.8/34.9mm).
SRAM: Braze-on.


Shimano: Mechanical, hydraulic.
Campagnolo: Mechanical (hydraulic coming).
SRAM: Mechanical, hydraulic.


Shimano: Double, triple. 165-180mm.
Campagnolo: Double. 170-175mm.
SRAM: Single, double. 165-177.5mm.


Shimano: 8/9/10/11-speed (min, 11T; max 34T).
Campagnolo: 10- or 11-speed (min, 11T; max 32T).
SRAM: 10- or 11-speed (min, 11T; max 42T).


Shimano: 2×8/3×8/2×9/3×9/2×10/3×10/2×11.
Campagnolo: 2×10/2×11.
SRAM: 1×10/2×10/2×11.


Shimano: Short, medium, long.
Campagnolo: Short, medium.
SRAM: Short, medium, long.


Shimano: Rim, centre-mount/direct-mount.
Disc, post-mount/flat-mount.
Campagnolo: Rim, centre-mount/direct-mount.
(Disc, post-mount/flat-mount).
SRAM: Rim, centre-mount.
Disc, post-mount/flat-mount.


Shimano: BSA/ITA/BB86.
Campagnolo: BSA/ITA/BB86/BB30/PF30/BBright/BB386.


– Entry-level/novice: Shimano Tiagra (10-speed)105 (11-speed), or SRAM Rival (11-speed).

– Enthusiast: Shimano Ultegra (11-speed)Ultegra electronic Di2 (11-speed)Campagnolo Potenza (11-speed) or SRAM Force (11-speed).

– Extravagant: SRAM eTap (11-speed), Shimano mechanical Dura-Ace (11-speed)Shimano Dura-Ace Di2 (11-speed), or Campagnolo Record (11-speed).


There are a variety of intricacies and complexities that have not been explored here. For those wanting more information, take a look at this article on bottom brackets, another on assembling the parts for a custom bike build, and finally, this article that describes the various incompatibilities that can arise when mixing groupsets.

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