A 50/34 crankset with an 11-30 cassette is not a bad combination and provides a number of benefits such as:
- High Gearing
The highest available gear is 50/11 which results in a 4.54 gear ratio.
The term gear ratio indicates the number of rotations made by the rear cog and wheel per 1 full revolution of the cranks. In this case, the rear wheel will make 4.54 rotations.
This value is important because it has a direct impact on the top speed that a bike can reach via pedaling.
The higher the gear ratio, the faster the bike can be. The gear ratio can be increased by getting a larger chainring and/or a smaller rear cog.
The other two factors determining speed are RPM (rotations of the cranks per minute) and wheel circumference.
A higher RPM equals more rations of the rear wheel per 1 minute and thus a greater traveled distance and speed. Wheel circumference directly influences the traveled distance per 1 minute too.
In other words, if two bikes have identical gearing but different wheel sizes, the bike with the larger wheel will be faster when the RPM is the same.
The table below contains the top speed that a 50/11 combination generates at different RPMs when using standard 700×25 tires.
|RPM||Speed kph||Speed mph|
Conclusion: 50×11 gives you plenty of top speed. At 90 RPM, the bike will be moving at over 50km/h. Consequently, it will be possible to spin out only during extreme descents.
Note: Spinning out occurs when the bike is moving faster than the speed that one can generate by pedaling. At that point, spinning the pedals does nothing to propel the bike forward.
- Low Gearing
The lowest gear in this case is 34/30 and has a 1.13 gear ratio that will allow you to conquer massive hills.
The lower the gear ratio, the easier it is to pedal because each revolution of the cranks results in fewer spins of the rear wheel.
Truth be told, trained cyclists may consider the gear needlessly low. But if you’re just starting out or want a bicycle primarily for commuting rather than to exercise or become a stronger cyclist, then the low gearing is just fine.
Another benefit of the lower gear is that you will experience less joint stress.
However, cassettes with a big (30T+) rear cog have a downside – large jumps between the gears.
The table below compares the gradation of 11-speed 11-30, 11-28, and 11-25 cassettes.
Up until the 5th cog, the jumps are the same. But then, the 11-28 and 11-30 cassettes have larger jumps in comparison to the 11-25 cassette (15-17 vs. 15-16).
The largest jump is found between the 9th and 10th cog on the 11-30 cassette and consists of 3 cogs (24T to 27T).
Of course, the difference isn’t massive, and most casual cyclists wouldn’t care. However, those who want to have smaller jumps between the gears allowing them to maintain the smoothest possible cadence will benefit from getting a cassette with a smaller large cog such as 11-25.
The trade-off is that you will lose the bail-out gearing that comes with the 30T cog.
Summary: What You Need To Know
- A compact 50/34 crankset is a good choice for cyclists who plan on riding seriously.
- Combining a 50/34 crankset with an 11-30 cassette is also a very decent option because you have the best of both worlds – very high gears and very low gears.
- For some people, a 30T large cog may be too large, especially if the terrain is mostly flat. In that case, it’s logical to replace the cassette with 11-25 or 11-28 and benefit from the smaller jumps between the gears which make it easier to maintain a smoother cadence and thus improve your average speed and efficiency.