There’s a mind-blowing array of gearing options available today. Heck, the number of cogs on a cassette is increasing faster than the number of blades on a razor. It seems like every week there is another cog in the mix—along with six varieties of each cassette. Sometimes it can be a little overwhelming. Let’s take a second to break it all down.
We’ll make sure everyone is on the same page before I start throwing terms around.
• Cog – A toothed gear that is part of a chain drive
• Chainring – A front cog, specifically, the type that attaches to the crank via a spider.
• Spider – A spider is a multi-armed fixture found on the driveside of the crankset and provides the interface between the driveside crank arm and one or more chainrings
• Crank Arm - The arm that connects the pedal to the spindle
• Spindle – Both crank arms attach to a spindle, which rotates within the bottom bracket
• Bottom Bracket – The bearing assembly housed in the frame’s bottom bracket shell. These bearings allow the crank to spin freely when the spindle is passed through either end and fixed in place between the crank arms
• Cassette – A cluster of cogs and spacers designed for use on a rear wheel with a freehub
• Gear Ratio – The front chainring tooth count divided by the rear cog tooth count for a particular combination
• Double – A crankset with two chainrings
• Triple – A crankset with three chainrings
• Standard – Referring to the ‘standard’ crankset configuration, a standard utilizes a 53-tooth large chainring and a 39-tooth small chainring
• Compact – Referring to the crank assembly, compacts usually come with a 50-tooth large chainring and a 34-tooth small chainring
• Mid-Compact – Referring to the crank assembly, mid-compacts usually come with a 52-tooth large chainring and a 36-tooth small chainring
Why Make Changes?
Spinning, also known as cadence, is the number of revolutions per minute of the crank arms, independent of the speed of the bike. A generally suggested cadence for riding on flat terrain is 90 rpm, although it can vary. Gearing changes can be made if you are spinning too fast or too slow. If your cadence is too high, changing your crankset to larger rings might be a good idea. You most likely have a compact 50/34 and should consider a mid compact 52/36 or even a standard 53/39. The opposite problem is true if you find yourself spinning too slowly when climbing. In this situation, consider changing to a cassette with a larger top-end gear.
Most cranksets these days are doubles. In some instances road bikes will have triples, but triples are becoming less popular due to a wider range of gearing available in the rear, accomplishing the same ratios. For instance, with an Ultegra 52/39/30 triple paired with an 11-28 cassette the easiest climbing gear ratio can be accomplished with the new 11-speed Ultegra with a double 52/36 and an 11-32 cassette. See the table below for a full comparison of ratios between the two groups.
For the longest time, road bikes came with standard 53/39 cranksets. Then came the introduction of the compact 50/34-tooth combination. The compact can be a popular option for those living in hilly areas, needing the larger gearing for climbing and those less concerned about downhill speed. The mid-compact 52/36 has also emerged as a nice compromise between the standard and the compact. Each of these is designed for different riding styles and will behave differently depending on the cassette it is paired with.
Cassettes come in many varieties. Depending on your setup, there could be a varying number of gears. Most likely you have a 9, 10 or 11-speed cassette. On most, the smallest gear is an 11 or 12-tooth. In the last few years, the larger gears have been increasing in size to facilitate easier climbing and component manufacturers have built special derailleurs to accommodate these much larger gears. This is something to keep in mind if you want to swap your cassette. Make sure that your derailleur can accommodate the larger gearing.
When considering these cassette options, it’s also important to distinguish between tight and wide-ratio. A tight ratio cassette will have smaller incremental changes. For instance, gearing steps in 1-tooth increments (11-12-13-14) would be considered a tight-ratio setup. This is good to be aware of when selecting a cassette because larger jumps in gearing will have a more significant effect on cadence. New 11-speed systems can afford to have tighter ratios than older cassettes with fewer gears.
If you think you need to make some changes in gearing to improve your riding experience, figure out what you currently have, and what you would like to improve on. For easier spinning on hilly terrain, a cassette swap is a straightforward and easy way to improve your riding experience. It’s an easy change for the mechanics at your local shop, or it’s done easily enough at home as well. But, be aware that you may need to adjust chain length if you are making a big change.
Short and Long Cage Length Derailleur Options
Short cage (SS) Shimano 10-speed derailleurs are typically made to handle up to a 28-tooth cog on the cassette; the exception being Shimano rear derailleurs with the “A” designation following the model code (e.g. 6700-A) which can handle up to a 30-tooth cog. Long cage (GS) 10-speed rear derailleurs are also limited to 28-tooth max cog sizes, but will work with triple chainring cranksets.
Shimano 11-speed groups have a short cage (SS) rear derailleur option that is built to accommodate up to a 28-tooth cog. For riders requiring a lower gear range, a wide-range, long cage (GS) rear derailleur option is available to handle up to a 32-tooth cassette.
If you have a SRAM component group and wish to use a cassette larger than 28 teeth, the WiFLi long cage option on their derailleur groups will be necessary. SRAM’s WiFLi rear derailleurs will take up to a 32-tooth cog.