How To Understand Shimano Groupsets

When purchasing a new bike it is easy to be bamboosled (technical word) by seemingly endless technical sales blurb (another technical word). In truth the blurb is often little more than an attempt to make you feel inadequate and thereby over sell you a bike you by no means need or desire but will now feel inferior if you do not purchase immediately. Conversely the use of blurb you don’t understand can make a high profit sale an easy win for any sales person.

No where is such behavior more painfully evident than in references to ‘group sets’. So we thought we’d take 5 minutes to break it down. 

And here’s why it matters. 

The group set is a large proportion of what determines the efficiency and ease with which your energy output in transferred into wheels rolling along the road. Clunky transitions, poor braking and a general sense of things not working as they should can quickly ruin any ride.

Firstly let me be explicit about the constraints I am imposing upon this post. 

When it comes to transmission parts (more of that shortly) there are a number of brands available the most popular being, Shimano, SRAM, Campagnolo. For the purposes of this post I am however going to focus purely on Shimano road bike group sets. The others we will come to in later posts. The only real rationale for doing so is Shimano’s percentage share of the market is huge, ridiculously huge! 

This post doesn't aim to be exhaustive, if it was it would be called a 'book' but rather to outline the answers to questions many feel too fearful to ask. 

“Group set” refers to those collection of parts (the group of) which when placed together enable the smooth running of the bikes transmission. 

Transmission is best understood as the distribution of power into movement via what we commonly call gearing. 

Transmission includes the following parts: 

Cassette/Freewheel: The collection of sprockets placed on your rear wheel, typically either, seven, eight, nine, ten or eleven although SRAM have just releases a twelve speed option. 

A cassette differs from a free wheel in three main respects. 

1: A free wheel is normally one unit. When removed the whole thing comes off in one go. A cassette is a collection of individual sprockets held together. The nicer/more expensive your cassette the more of the individual rings come apart. On most cassettes only the top three chain rings separate. 

2:  Fitting: You need a different tool to remove each of these. A freewheel screws onto the wheel’s axle while a cassette drops on to splines. 

3: Weight. Free wheels are considerably heavier and tend to be limited to lower spec bikes which are generally no more than 7 speed. Weight is also indicative of engineering quality and thus free wheels tend to be cheaper than cassettes. 

If your bike has a total number of gears divisible by 5, 6 or 7 it may be running a sprocket, 7 or more and it’s almost certainly a cassette. 

When you book in for a repair your bike shop wont ask you how many gears the bike has but rather ‘what speed is it’ ie: the 5,6, 7, 8, 9, 10 or 11 sprockets on the back wheel?’

Chain: For the most efficient running your chain should match your group set and must be specific to the speed (number of sprockets) of your bike. The higher the speed the thinner the chain. 

While you ‘could’ in a less than ideal world run a Tiagra 10 speed chain through a 105 10 speed cassette you absolutely could not run a 7 speed chain through the same cassette.  

Chain Rings/Crankset: Those collection of sprockets attached to your drive side crank arm; “The big ones”. 

Lower group sets will have the option of a triple chain ring while the higher end have just a double chain ring. 

Reference to a ‘compact crank’ means that the smaller ring is notably smaller and thus provides a much lower gear eg: 50:34. It was traditionally thought that compact belonged to those who fear hills while standard double chainrings belong to those who love to sprint. The increased size of rear cassettes now challenges this thinking. 

Front Mech or Front Derailleur: That mechanism which guides the chain across your front chainrings. Typically connected to the left hand shifter. 

Rear Derailleur: That mechanism which guides the chain across the rear cassette/freewheel from below and contains two jockey wheels. Typically cabled to the right shifter.  Rear derailleurs come in either short or long throw (that’s an entirely separate post). 

Shifters: That system of levers which enables you to ‘shift’ gears. Shifters are increasingly located in the same mechanism that enables you to break although may be located on the down tube of an older bicycle or just next to the brake and controlled with the thumb on a bike with flat handlebars. 

Note that cabling is usually** required in order that shifters might influence the movement of mechanisms. 

Now back to what we’re here for; understanding the rhetoric concerning Shimano group sets and why it matters. 

In order from low to high in both price and quality it goes something like this. . . .


Commonly found on low end road bikes. Prevalent on Carrera (Halfords) 

Sora 9 Speed

Common on entry level road bikes although appearing with frightening frequency on increasingly more expensive bikes. 

+ Price

- Expect very crude functionality. 

Available on bikes £500 - £850

Tiagra 10 Speed (4700) 

Good kit not to be scoffed at even if there are superior options widely available. 

+ Refined, incremental shifts available as a triple so great for those new to the hills who want to avoid compact. Excellent value for money when found on an entry level road bike and there’s lots of those out there. 

- Disliked by serious roadies mainly due to its weight. 

Available on bikes from £750 to £1250

105 10 Speed (5800)

At this point things begin to get noticeably and significantly better. 105 says ‘I’m in the game and I’m not backing down’. 

+ Really good kit. In the words of our legendary mechanic “It just does what it’s told”

-  Becoming expensive

Available on bikes £1000+

Ultegra 10 and 11 Speed (6870, 6800)

Expect to find this kit on bikes which belong to people who people who either take their cycling seriously or have all the gear and no idea.

+ Superior kit used by a number of pro teams the world over. Expect fine incremental shifts from a lightweight piece of beautifully engineered kit. 

- Needs and merits being well cared for. 

- £££

Expect to find Ultegra on bikes £1k - £3k and over

Dura Ace 11 Speed (9070 Di2, 9000)

Dura Ace towers over the world of Shimano group sets with incredible finnesse. It's a groupset of real beauty but in truth few of us have the waist line or sheer performance to merit its wonders.  

+ The daddy of the Shimano range. Super lightweight with the kind of engineering that leaves most of us speechless. Pro team standard kit.  Utterly beautiful. 

- Get your mortgage application ready. 

You’re at the top end of the market and the price tag will make that clear. 

What separates the above from one another might best be encapsulated in one word ‘finesse’. I like to think of Sora as an over weight drunk man walking home from the pub. Sure he’ll get home, he always does, but sometimes there’s more to life than just getting home. In contrast Dura Ace is like a ballerina who has trained for decades and moves through ever minutia of the nut cracker in such a manner as to leave the audience in awe of her beauty.  

Group sets make a difference but they’re no disguise for your own relentless commitment to putting in mile after mile, keeping your performance up and your weight down. Drunk men need not attempt ballet.

Most of us will never be ballerinas but we ought never to settle for stumbling home.  

A group set is probably the most expensive upgrade you will ever make to your bike. Choose carefully. 

Consumer tip 1#: Avoid Sora if you can. We’re now seeing Sora pop up on £800 +  bikes which makes no real sense.

Consumer tp 2#: Don't be blinded. If you're out to buy a new bike and the guy in the bike shop just want to go on and on about the amazing value of an Ultegra group set on a bike with a retail value of just over £1000 ask yourself why this might be the case. What doesn't he want you to focus on? How does the weight of the groupset compare to the weight of the overall bike? Does the fit work for you or is he pushing hard to shift old stock. 

We’re sure to have missed lots out, maybe you ride a Sora groupset and love it? We await your thoughts with baited breath. 

If you'd like to upgrade your group set talk to us. We'd love to help you make the right decision and offer free fitting. 


** The invention of Di is the only exception to this rule but that’s another post for another day.