RENTHAL Ultralight Aluminium Rear Sprocket (blue) 50 Teeth for KTM SX, XC 85, 105, HUSQVARNA TC 85 and GAS GAS MC 85 2003-2027

On KTM SX 85, SX 105, XC 105, HUSQVARNA TC 85 and GAS GAS MC 85 from 2003 to 2027, the RENTHAL Ultralight (bleue) 50 dents 441U-428-50GPBU aluminium rear sprocket fits in place of the original part. Bolted to the rear wheel, the sprocket takes all of the engine's force through the chain. An aluminium sprocket is the lightest option on the market: the suspension works better and the wheel picks up speed more easily, at the cost of faster wear than a steel sprocket.

Specifications

• Brand: RENTHAL
• Manufacturer part number: 441U-428-50GPBU
• EAN code: 5026190152836
• Chain pitch: 428
• Mud-relief grooves
• Material: 7075 aluminium (Ergal)
• Weight: 360 g
• Engine: 2-stroke

When to replace it?

• Teeth worn to a point or into a hook shape, worn down on one side only.
• Chain that lifts away from the sprocket when you pull it rearwards.
• Drivetrain noise, jerkiness or a chain that jumps under load.

Check the sprocket every time you service the chain. Always replace the rear sprocket, front sprocket and chain together: a new part running with worn ones wears out very quickly. Aluminium wears faster than steel, especially in sand and mud.

Fitting tips

1. Clean the hub and check that it isn't cracked or distorted.
2. Fit the sprocket the right way round (markings facing out) and tighten the bolts in a criss-cross pattern to the manufacturer's torque, with medium-strength threadlocker if the manual calls for it.
3. While you're at it, replace the front sprocket and the chain if they're worn.
4. Set the chain tension as per the manual, with the wheel aligned, then lube it with a suitable chain lube.
5. Recheck the bolt tightness and the chain tension after the first ride.

Why RENTHAL?

Renthal was born in England in 1969 from the partnership of Andrew Renshaw and Henry Rosenthal (hence the name), starting out with trials handlebars, and has made its handlebars in its own Manchester factory since 1975. In 2004, it became the first aluminium handlebar fitted as original equipment on a Japanese off-road bike, and Honda, Kawasaki and Suzuki use it on their performance motocross models.

Spare parts and items to plan

• Front sprocket : RFX · PBR
• Drive chain : AFAM · RENTHAL 428
• Chain lube : LIQUI MOLY 400 ml · MUC OFF 400 ml

Frequently asked questions

Aluminium or steel?
Aluminium is lighter and works well for motocross and racing. Steel lasts longer: it's the best choice for enduro, sandy terrain or if you put in a lot of hours.

Should the chain be replaced at the same time?
Yes, if it's worn: a stretched chain wears out a new sprocket in a few hours.

Compatibility

Check the exact model and year of your bike in the list below before ordering.

Fits:
GAS GAS MC 85 2027
GAS GAS MC 85 2026
GAS GAS MC 85 2025
GAS GAS MC 85 2024
GAS GAS MC 85 2023
GAS GAS MC 85 2022
GAS GAS MC 85 2021
HUSQVARNA TC 85 2027
HUSQVARNA TC 85 2026
HUSQVARNA TC 85 2025
HUSQVARNA TC 85 2024
HUSQVARNA TC 85 2023
HUSQVARNA TC 85 2022
HUSQVARNA TC 85 2021
HUSQVARNA TC 85 2020
HUSQVARNA TC 85 2019
HUSQVARNA TC 85 2018
HUSQVARNA TC 85 2017
HUSQVARNA TC 85 2016
HUSQVARNA TC 85 2015
HUSQVARNA TC 85 2014
KTM SX 85 2027
KTM SX 85 2026
KTM SX 85 2025
KTM SX 85 2024
KTM SX 85 2023
KTM SX 85 2022
KTM SX 85 2021
KTM SX 85 2020
KTM SX 85 2019
KTM SX 85 2018
KTM SX 85 2017
KTM SX 85 2016
KTM SX 85 2015
KTM SX 85 2014
KTM SX 85 2013
KTM SX 85 2012
KTM SX 85 2011
KTM SX 85 2010
KTM SX 85 2009
KTM SX 85 2008
KTM SX 85 2007
KTM SX 85 2006
KTM SX 85 2005
KTM SX 85 2004
KTM SX 85 2003
KTM SX 105 2011
KTM SX 105 2010
KTM SX 105 2009
KTM SX 105 2008
KTM SX 105 2007
KTM XC 105 2009
KTM XC 105 2008