Choosing grips seems simple, but thickness dramatically impacts comfort and control on your mountain bike. There's no single "best" – it hinges on your riding style, hand size, and personal preference. Let's break down the contenders:

Thin Grips (Typically <30mm Diameter):

- Pros:

Precision & Feel: Offer direct bar feedback for precise steering inputs and technical maneuvering.

Less Arm Pump: Reduce forearm strain on long climbs or endurance rides by requiring less grip force.

Barend Friendly: Easier to pair with ergonomic barends for climbing positions.

Lighter: A minor, but real, weight saving.

- Cons:

Less Vibration Damping: Transmit more trail chatter, potentially causing fatigue and numbness on rough terrain.

Reduced Cushioning: Less material means less impact absorption for hard landings.

Can Feel Harsh: Especially for riders with larger hands or sensitivity issues.

Thick Grips (Typically >30mm Diameter):

- Pros:

Superior Comfort & Damping: Excel at absorbing vibrations and smoothing out bumps, reducing hand fatigue on chunky descents.

Enhanced Cushioning: Provide more padding for impacts and landings.

Better Fill for Larger Hands: Often feel more natural and secure for riders with bigger palms.

Increased Grip Surface: Can feel more planted, especially with gloves.

- Cons:

Reduced Bar Feel: Mute feedback, potentially making subtle steering adjustments harder.

Increased Arm Pump: Can require more grip strength to hold firmly, tiring forearms faster, especially on climbs.

Bulkier Feel: Some riders find them less precise or nimble.

The Verdict? It Depends!

- Downhill / Enduro / Park Riders: Prioritizing comfort and vibration damping? Thicker grips are usually the weapon of choice for surviving brutal descents.

- XC / Trail / Climbers: Valuing precision, low weight, and reduced arm pump on long efforts? Thinner grips often shine.

- Hand Size Matters: Smaller hands usually prefer thinner grips; larger hands often find thicker grips more comfortable.

- Lock-On is Key: Whichever you choose, lock-on grips (with metal clamps) are essential for security and no slippage.