The transmission is the link between your engine and your rear wheel. Wear signs, intervals, correct tension, and the kits worth buying.
Sommaire · 6 parties
01How long a motocross chain kit lasts
| Use | Average service life |
|---|---|
| Motocross racing (sand, mud) | 30-60 h |
| Enduro | 60-100 h |
| Road / trail | 200-400 h |
A motocross chain wears 3-5× faster than a road one: sand and dirt thrown up at it, brutal loading under acceleration and deceleration, and often not enough lube.
02The signs it needs replacing
The chain
- Tight spots: spin the rear wheel in the air and watch: if the chain binds at one point, it's finished
- Stretch: measure 20 links. New = 635 mm (pitch 12.7 mm × 50 = 635). Over 640 mm (+1 %) → worn. Over 645 mm → dangerous.
- Side play: waggle a link sideways. More than 2 mm means the pins are worn
The front and rear sprockets
- Hooked teeth (wave or shark-fin shape) → worn, replace them
- Pointed teeth instead of rounded → worn
- Golden rule: you ALWAYS replace chain + front sprocket + rear sprocket together. A new chain on a worn sprocket is destroyed in 10 hours.
03Maintenance to make it last
After every motocross ride
1. Low-pressure hose (keep the pressure washer off the chain) 2. Chain cleaner if it's really caked (WD-40 Specialist, Motul Chain Clean) 3. Lube with O-ring chain grease (Motul C2, Bel-Ray Blue Tac)
The correct tension
- Bike on a stand, rear wheel off the ground
- Halfway along the lower run (between the two sprockets): 40-50 mm of slack (3-4 fingers)
- Too tight → premature wear plus a broken output shaft
- Too loose → the chain jumps, chain and sprockets wear, and it's dangerous
04Chain kits worth buying
| Brand | Type | Average price | Durability |
|---|---|---|---|
| DID 520 ERV7 | O-Ring Gold | €150-200 | Excellent |
| RK 520 MXZ4 | Non O-Ring | €80-120 | Good (pure motocross) |
| Regina 520 ZRE | Z-Ring | €130-170 | Very good |
| Supersprox Stealth | Bi-metal rear sprocket | €60-80 | Excellent |
Sources: 24mx.fr and crossmoto.fr catalogues
05O-ring or not?
- Without O-rings: cheaper, lighter, less friction. Ideal for pure motocross (it's not going to last long either way).
- O-ring / X-ring: more expensive, longer-lasting, less maintenance. Ideal for enduro and trail.
The chain doesn't lie: lube it after every ride and keep the tension right, and it lasts twice as long.
06Count in hours, not in weeks
The intervals above are given in riding hours. On a bike that goes out three weekends a month then sleeps all winter, the gap with the calendar becomes enormous. An engine hour meter that runs by itself stops you replacing a chain kit too early, and above all too late.
Un compteur d'heures fiable + un carnet automatique, c'est ce que fait HOROTAG RUUVI.
Boîtier sous la selle, app gratuite, sans abonnement. 129 € payés une fois.
Voir HOROTAG RUUVI
