Short answer: Yes. A quality chain tensioner is one of the most important upgrades you can make to your motorized bicycle, even if your chain appears to run fine without one.
Why You Need a Chain Tensioner
1. Chain Slack is Inevitable
Motorized bicycle drive chains naturally develop slack due to:
- Chain stretch over time
- Rear wheel sprocket variations
- Frame flex during riding
- Temperature changes affecting chain length
2. Prevents Dangerous Chain Derailment
A loose chain can:
- Jump off the sprocket at high speed (dangerous!)
- Get caught in your rear wheel spokes
- Cause sudden loss of power while riding
3. Reduces Noise and Vibration
Properly tensioned chains run quieter and smoother. If you hear a "slapping" or "popping" sound from your drivetrain, inadequate chain tension is often the culprit.
4. Extends Chain and Sprocket Life
Consistent tension reduces wear on both your chain and sprockets, saving you money on replacements.
Why the Kit-Included Tensioner Isn't Enough
Most engine kits include a basic tensioner, but these often have problems:
- Plastic or low-quality wheels that wear quickly
- Weak mounting brackets that slip
- No spring mechanism for automatic adjustment
When You Might Skip a Tensioner
The only situation where a tensioner is optional is if your motorized bicycle has horizontal dropouts that allow precise rear wheel positioning AND you check/adjust chain tension before every ride. Most riders find this impractical.