If you are looking for a bike to buy, the 18-speed bikes and 21-speed bikes are some of the most popular out there. Still there are not many people that understand the differences between these two groupsets.
18 speed bikes are usually suited for rougher and shorter terrain and tend to be cheaper overall. Conversely, 21 speed bikes are smoother and faster but generally more expensive.
As an avid cyclist I have ridden both 21-speed and 18-speed bikes and I understand the difference in the technologies used in the groupsets. I intend to help you get an understanding of the two groupsets so that you can make the best choice of what bike to buy.
How Many Gears Does a 21-Speed Bike Have
A 21-Speed bike typically comes with seven sprockets otherwise referred to as seven gears on the rear wheel and 3 chainrings or three gears in the front. You get 21 multiplying the gears hence the 21-speed bike.
You can typically achieve up to 21 gear ratios switching between the sprockets and chainrings.
What is A 21-Speed Good For
21-speed bikes offer a range of gear combinations making it possible to use your energy more efficiently even when climbing steep ascents.
These kinds of bikes are made for riders that love to enjoy leisure rides. Given the gear combinations, you can get high speeds while applying less force.
At the highest gears, the chain will usually be on the smallest cog on the rear and the largest chainring in the front. This makes it possible to spin the rear wheel with the same amount of force thus pushing the bike further.
As previously mentioned you can exert a lot more power with a 21-speed bike as compared to most other bikes.
Usually when you shift to the lowest gear the chain will jump to the largest sprocket and the smallest chainring on the cassette. In such a scenario you will have to pedal harder to get the same number of spins on the rear wheel.
One thing to note abo0ut bikes with a large number of gears is that overlapping is quite common. This happens when two or more rear sprocket and chainring combinations result in the same cadence and ratio.
If you are riding a 21-speed bike, overlapping is usually unavoidable as compared to bikes with fewer gears such as the 18, 12 or 7-speed bike.
How Many Gears Does an 18 Speed Bike Have
18-speed bikes true to their name come with 18 gear combinations.
You get an 18-speed by multiplying the 3 chainrings on the front and the 6 cogs on the rear wheel of the bike.
What are 18 Speed Bikes Good For
If you are looking to upgrade from a lower-speed bike, the 18-speed bike is one of the better options out there. They provide a range of features to increase your speed and can be used for rougher terrain as compared to bikes such as the 21-speed.
Even though 18-speed bikes come with only 6 sprockets it works similar to the 21 speed as the highest gear settings will provide maximum speed and momentum and the smallest gears will be best when you are going up steep ascents.
Cyclists with fewer gear options bikes such as the 14-speed, 12-speed or the 7-speed tend to be more adapted to using more force when pedaling to get higher speeds. This could temporarily make them unable to use the maximum potential of an 18-speed when riding on inclines.
Still such riders will overtime be able to enjoy the more efficient gearing of the 18-speed bike.
Given that 18-speed bikes are typically easier to handle and comparatively lighter since they have much fewer pieces of hardware they tend to be great for beginner riders or people with less experience riding.
Moreover, new riders do not understand how to select the most efficient cadence when they are presented with too many options. As such fewer gears may result in much less fuss and choice.
18-speed bikes are typically faster and more comfortable particularly if you have been riding low speed or fixed gear bikes. However they may not be so much suited to longer routes as compared to more jacked up or higher end options.
Since the number of cogs in these bikes is just six, you will get more tired over time.
As for overlapping gears, it will happen in an 18 speed bike though it will be a much rare occurrence.
18-Speed Bike VS 21-Speed Bike: Which is Better
Now that we understand the functioning of both the 21-speed and the 18-speed bike, we need to compare the two so that you can make a better decision on which is best for you.
- Gear Setup
The most glaring difference between these two bikes is the different gear setups and number of gears. 18-speed bikes come with 6 sprockets and three chainrings while 21-speed bikes come with three chainrings and 7 sprockets.
- More Pedaling Power and Momentum Building
Since 18-speeds have one less cog the 21-speed is better in situations such as:
- If the smallest cog of the 18 speed happens to be larger than that of the 21-speed, you will not achieve comparatively high speeds and the ride will be less comfortable.
- If the largest cog is smaller than that of the 21 speed bike the bike will struggle on steep ascents
- Price Difference
21-speed bikes come with newer technology and tend to be more comfortable and faster as compared to lower gear bikes. This means that 21-speeds will be more expensive as compared to something such as an 18-speed bike.
Weight happens to be a very critical aspect to take into consideration when purchasing a bike. Lightweight bikes tend to be easier to ride and handle as compared to heavier bikes.
Even though the 18-speed and the 21-speed bikes have similar weight, the 18 speed is a little lighter given that it has fewer hardware.
- Gear Confusion
Regular riders and experienced cyclists usually have no issues switching gears depending on the riding conditions. However this can be a problem for beginner cyclists especially when there are too many gears to choose from.
In the case of beginner cyclists, the 18-speed is recommended then one could always upgrade to the 21 speed bike once they have some experience under their belt.
- Suitability for Long Distance Rides
Riders who intend to go on long rides should go with 21-speed bikes as they provide more comfort and ease of handling.
Given the large number of gear combinations one can maintain their pedaling cadence and use energy more efficiently with a 21-speed bike on long routes as compared to the 18-speed bike.
- Graveyard Shift
This is a term that refers to shifting that causes the most stress on the bike chain.
In most bikes these tend to be the largest and smallest gear positions where the chain is adjusted on the largest rear cog and the smallest chainring and vice versa.
Riding the bicycle on such gears puts a lot of strain on the chain which results in premature wear. 21 speed bikes with one more sprocket can be particularly vulnerable to this as compared to the 18-speed bike.
Choosing between two bikes can be a very subjective process especially when there is not that much of a difference. The decision will vary depending on individual preferences and expectations.
If you have a preference for long rides and steep terrain a 21-speed bike is more preferable to an 18-speed bike. On the other hand if you just need something that can be faster and better than your single speed say something for your commute an 18-speed would be the cheaper option.