The advantages of a single chainset: omit other discs and front derailleur, lighter weight; less gear shift coordination, more concise; omit the position of the front derailleur, more convenient maintenance of the chain gear shift, and reduced failure rate.
The disadvantages of a single chainset are limited to both the minimum gear ratio and the maximum gear ratio, which are not suitable for large slopes or high speeds flat roads.
So, is it right for you to have a single chainset, double chainsets, or even triple chainsets? You should answer the following questions:
1. What type of MTB Rider are you? Trail, Enduro, Cross Country, or Marathon?
2. What kind of MTB do you ride? 27.5" Hardtail, 29" Hardtail, 27.5" Full suspension, or 29" Full suspension?
3. What is your fitness level? Very fit/ Race level, Good Fitness, or Weekend Warrior?
4. Do you always ride the same terrain? Always the same trails, Mostly the same trails, or Always Changing？
5. What kind of trails? Up& Down, Downhill Focused, or Mainly Flat?
6. What is the average meter of elevation during your ride? <100m, 100-500m, or >500m?
7. What is the average length of your ride? <15km, 15km - 45km, or >45km?
8. What is your top speed? <30km/h, 30-45km/h, or >45km/h?
9. What is your lowest speed? <10km/h, 10-20km/h, or >20km/h
10. How important are small gear steps for you? Not important, I don't mind having big gear steps, important, I prefer to have small gear steps, or I don't know?
For more information please visit shimano.com/advice.