When cycling with a double or triple chainring, it's always useful to ask yourself which chainring to choose.
Indeed, riding between 25 and 30 km/h on flat terrain can be done with different gear ratios. Here's an example with a 34, 39, and 50 teeth chainring (thus covering the use of a compact chainset):
| Chainring - Gear Ratio | Speed |
|---|---|
| 50 x 23 | 27.65 km/h |
| 34 x 17 | 25.44 km/h |
| 39 x 19 | 26.11 km/h |
| 34 x 16 | 27.03 km/h |
| 39 x 18 | 27.56 km/h |
| 34 x 15 | 28.83 km/h |
| 50 x 22 | 28.91 km/h |
| 39 x 17 | 29.18 km/h |
| 50 x 21 | 30.29 km/h |
| 34 x 14 | 30.89 km/h |
| 39 x 16 | 31.01 km/h |
| 50 x 20 | 31.80 km/h |
| 39 x 15 | 33.07 km/h |

On the road, it's indeed the same whether you use one gear ratio or another, except that one chainring is more suitable than the others. Assuming that it's very important to pedal at the same speed and that changing gear ratios too often is tiring, let's adapt our way of using gear ratios. The solution lies on the cassette side.
Nowadays, bike cassettes come with 8 to 10 gears, and sometimes even 11. How are these gears spaced to go from 13 teeth to 25 teeth?
Take a look at your bike, there's a good chance that the smaller gears are spaced by 1 tooth (13, 14, 15, 16, 17) and then by 2 teeth (19, 21, 23, 25) like in this Shimano 9-speed cassette from 13 to 25 teeth.
So what's the best chainring for flat terrain?
The best chainring for flat terrain is the one that allows us to stay within the range of gears that are spaced by 1 tooth. With the 50-tooth chainring, going from 21 to 23 results in a difference in speed of more than 2.5 km/h.
From 15 to 17 with the 39-tooth chainring, we have 3 gears spaced by 1 tooth with just a 2 km/h difference for each tooth.
With this chainring on gears spaced by 1 tooth, the pedaling rhythm can be maintained without too much change, which is better for the cyclist.
Cycling Training
Managing your training, preparing your outings, monitoring your fitness level, being in tune with your body, in cycling as well as running, is called preparation and has only benefits afterwards.
Question : Does pedaling happen on the
small or large chainring in cycling ?
Two tools allow for the
Average speed calculation and
Distance calculation in kilometers:

Cycling
The cyclist :
How to properly adjust your bike and position (saddle height, stem, frame height) :
position on the bike. Reflections on
cyclist visibility and the
mandatory helmet.
Paris-Brest-Paris : Bike ride about 1,200 km between Paris and Brest, strating from Rambouillet (78) - Time limit 90 hours - Characteristics : organised every 4 years, 6,000 participants, with over 60 nations represented.
Le
1000 du Sud : Brevet de Randonneurs of 1,000 km bike ride with elevation gain in complete autonomy, starting from Carcès (83 - Var) - Time limit 100 hours - Characteristics: Takes place in Provence, every year. Elevation gain exceeding 15,000 m in recent editions.
US Métro's Tour de France: Embark on a 4,800 km bike ride near the border, through the mountain passes of the Alps and the Pyrenees, that can be completed in either 30 or 60 days.