Sprocket Change: From 16 to 15 Teeth – Fine-Tuning the Gear Ratio
Today, a small but effective upgrade was on the agenda: I replaced the front sprocket of my bike from 16 teeth to 15 teeth. At the same time, I also rotated the chain tension blocks to optimally adjust the chain tension. The entire conversion took approximately 30 minutes.
Why the Smaller Sprocket?
Switching to a smaller front sprocket changes the gear ratio, making the bike more agile and more responsive to throttle inputs. At the same time, the engine revs higher at the same speed, which provides advantages in technical terrain or tight cornering sections.
Technical Implications
The gear ratio is determined by the relationship between the rear sprocket and the front sprocket:
- Before: 42:16 = 2.625
- Now: 42:15 = 2.8
The top speed is affected by the change in gear ratio. The original top speed was 205 km/h with the 16-tooth sprocket. To calculate the new theoretical top speed, we use the ratio of the gear changes:
New Vmax = Standard Vmax × (old gear ratio / new gear ratio)
New Vmax = 205 km/h × (2.625 / 2.8)
New Vmax ≈ 192 km/h
This means a slight reduction in top speed while simultaneously improving acceleration.
Installation and Important Notes
Changing the sprocket is not rocket science, my points to follow:
- Tighten the sprocket nut to 100 Nm.
- Use medium-strength Loctite to prevent the nut from loosening due to vibrations.
- After installation, adjust the chain tension
And another tip… check three times whether you have the pinion gear on correctly, as it is misaligned and does not run centrally… I had to learn the hard way and now have grinding marks on the engine block because I had installed the sprocket the wrong way round.
As always, if you want to reach out – servus@paulwuehrer.com or use the comment function
cheers
paul
