The Motobike Mas 90/90-21 off-road motorcycle mousse insert is a nitrile rubber foam tire insert for enduro & MX front wheels. Standard fitment for full-size dirt bikes. Eliminates front pinch flats, reduces rotating mass. B2B wholesale from Tianjin, China.
| 1.1 Barra | Optimal speed performance |
|---|---|
| 0,8 bar | Best for deserts, grasslands, and gobi terrain |
| 0,5 bar | Optimal for forest trails |
| 0,3 bar | Extreme enduro mousse for technical off-road riding |
The Motobike Mas 90/90-21 off-road motorcycle mousse insert is a professional-grade closed-cell nitrile rubber foam tire insert engineered for the front wheels of enduro, motocross, and off-road motorcycles. The 90/90-21 is the standard front wheel size for virtually all full-size dirt bikes — making this mousse one of the most widely compatible front-end protection solutions in off-road racing.
This front mousse insert completely replaces the inner tube to eliminate dangerous front pinch flats, reduce unsprung rotating mass, and deliver consistent steering precision across the most demanding terrain. Available in soft, medium, and standard density formulations, the 90/90-21 mousse fits all standard full-size dirt bike front wheels.
As a Tianjin, China-based B2B manufacturer, Motobike Mas offers OEM private labeling, custom hardness formulations, and direct factory wholesale pricing for dealers, distributors, and race teams worldwide.
| Size | 90/90-21 |
| Fitment | 90/90-21 front tires (standard full-size MX/enduro front wheel) |
| Material | Closed-cell nitrile rubber foam |
| Density Options | Soft, Medium, Standard |
| Weight | Approx. 1.0-1.2 kg |
| Rotating Mass Reduction | Up to 40% vs. tube + heavy-duty rim lock |
| Effective Pressure Equivalent | 8-12 psi |
| Service Life | 200-500 racing miles typical |
| Country of Origin | Tianjin, China |
A front tire flat at speed is the most dangerous failure in off-road motorcycling — it causes immediate loss of steering control. The 90/90-21 front mousse eliminates this risk entirely. No pinch flats from square-edge log impacts, no puncture flats from rocks and thorns, no valve stem failures. For enduro racers navigating technical terrain and motocross racers landing heavy jumps, this means no DNFs from front-end failures.
Reducing unsprung rotating mass on the 21-inch front wheel dramatically improves steering response and suspension compliance. By eliminating the inner tube and allowing a lighter rim lock, the 90/90-21 front mousse reduces front wheel rotating mass by up to 40%. The result: lighter steering effort, reduced deflection off roots and rocks, and more precise front-end feedback.
Unlike pneumatic tires where front tire pressure changes with temperature, altitude, and riding time, a mousse insert delivers identical damping and steering characteristics from the first corner to the last. For enduro riders covering varied terrain over hours of racing, this predictability is invaluable for maintaining consistent corner entry speed and line choice.
The 90/90-21 front mousse allows riders to run effective pressures as low as 8 psi with zero risk of pinch flats. On loose over hardpack, wet roots, and sandy sections, this translates to significantly more front-end grip and confidence in corner entry. The foam absorbs square-edge impacts that would instantly collapse a tube at low pressure.
Once installed, the front mousse requires zero maintenance for the life of the tire. No air pressure checks before practice or race starts, no valve stem inspections, no gauges or pumps. For race teams managing multiple bikes and enduro riders preparing for long events, this simplifies preparation and eliminates one more variable.
Selecting the correct mousse hardness for the 90/90-21 front wheel is critical for both performance and safety. The wrong density can cause vague steering, excessive deflection, or premature wear.
| Density | Effective Pressure | Best Terrain | Rider Weight |
|---|---|---|---|
| Suave | 8-10 psi | Mud, sand, wet roots, slippery conditions | Under 70 kg |
| Médio | 9-11 psi | Mixed terrain, enduro, all-around use | 70-90 kg |
| Standard | 10-12 psi | Rocky, hard-packed, desert, high-speed | Over 90 kg |
This 90/90-21 mousse insert fits all standard 90/90-21 front tires — the industry-standard front tire size for full-size off-road motorcycles. It is compatible with virtually all full-size dirt bikes from every major manufacturer.
| Factor | Front Mousse Insert (90/90-21) | Front Inner Tube |
|---|---|---|
| Flat prevention | 100% — no front flats possible | Vulnerable to pinch flats, especially on log impacts |
| Steering precision | Consistent throughout race | Changes with pressure and temperature |
| Maintenance | Zero — install and forget | Check pressure before every ride |
| Rotating mass | Lower (no tube + lighter rim lock) | Higher |
| Safety | No sudden steering loss | Sudden control loss on front flat |
| Installation | Moderate difficulty | Easier |
| Terrain adaptability | Fixed by density choice | Adjustable via pressure |
| Reusability | Transfer to new tire (if in good condition) | Replace each tire change |
| Specification | 90/90-21 | 80/100-21 |
|---|---|---|
| Section Width | 90 mm | 80 mm |
| Aspect Ratio | 90% (taller sidewall) | 100% (taller profile overall) |
| Overall Diameter | Slightly larger | Slightly smaller |
| Typical Application | Enduro, trail, off-road | Motocross, supercross |
| Steering Feel | More front-end grip, slightly heavier steering | Lighter steering, faster turn-in |
| Best Terrain | Loose, soft, technical enduro | Hard-packed, berms, deep loam |
A 90/90-21 front mousse insert typically lasts between 200 and 500 racing miles, depending on terrain, rider weight, riding speed, and lubrication during installation. Front mousses generally wear more slowly than rear units due to lower heat generation from braking loads compared to the driving loads on a rear wheel.
Important: Never use petroleum-based lubricants on mousse inserts — they degrade nitrile rubber. Use only water-based mousse lubricant. Proper seating is especially critical on 21-inch front wheels where any imbalance will be felt through the handlebars at speed.
Motobike Mas is a Tianjin, China-based manufacturer of mousse inserts for off-road motorcycle racing tires. We supply dealers, distributors, race teams, and aftermarket brands worldwide with factory-direct pricing and full customization.
| Factory Pricing | Direct wholesale — no middlemen |
| OEM / Private Label | Custom branding, packaging, and colors |
| Custom Formulations | Adjust density and material properties including front-specific formulations |
| MOQ | Contact for minimums |
| Shipping | Sea (FOB Tianjin), air freight, DDP available |
| Samples | Pre-production samples for evaluation |
90/90-21 is a front wheel tire size — the industry standard front tire for virtually all full-size motocross and enduro motorcycles. The 21-inch diameter rim is universal across 250cc and 450cc dirt bike classes from every major manufacturer.
The 90/90-21 has a 90 mm section width with a 90% aspect ratio, while the 80/100-21 has an 80 mm width with a 100% aspect ratio. The 90/90-21 offers slightly more front-end grip and a slightly larger overall diameter, making it popular for enduro and off-road riding. The 80/100-21 provides lighter steering feel and is more common in motocross.
Typically 200-500 racing miles. Front mousses often last longer than rear units because they generate less heat under braking compared to the driving loads on a rear mousse.
If your motorcycle has a 21-inch front wheel and uses 90/90-21 front tires, this mousse will fit. This covers virtually all full-size motocross and enduro bikes from Honda, Yamaha, Kawasaki, Suzuki, KTM, Husqvarna, GasGas, Beta, Sherco, and more.
Yes. Many enduro and trail riders choose a mousse for the front wheel for safety and consistency while running a tube on the rear. However, running mousse on both wheels provides the best overall performance and flat protection.
Yes. B2B clients can request samples for evaluation before committing to volume orders. Contact our sales team to arrange sample shipments.
Typical lead time is 15-30 days for standard OEM production, depending on quantity and customization requirements.
