Sitta Aluminium Rear Sprocket for BMW HP4, HP4 Race & S1000RR HP Forged Wheel – 37-47 Teeth, 520 Pitch (204Y)

When the drivetrain is the last thing you want to think about mid-corner, the Sitta 204Y aluminium rear sprocket delivers the confidence to focus entirely on the riding. Precision-manufactured from high-grade aluminium and available in eleven tooth counts from 37 to 47, this sprocket is engineered specifically for the BMW HP4, HP4 Race, and S1000RR fitted with the HP forged wheel — giving you exact, repeatable power transfer whether you are chasing lap times or carving fast roads.

Key Features

• Lightweight aluminium construction weighs just 350 g at size 45, reducing unsprung mass for sharper steering response and faster acceleration.
• 520 pitch specification, optimised for performance and racing use on the HP4 and HP4 Race platform.
• Eleven tooth options spanning 37 to 47 teeth allow precise gearing adjustment to suit your riding style, circuit layout or road conditions.
• Carrier pattern: 70/100-5 hole — matches the BMW HP forged wheel carrier for accurate, straightforward fitting.
• Available in eight anodised finishes including hard-anodised, which outlasts standard anodising and resists wear under sustained high-load conditions.
• Part number 204Y guarantees an exact reference for ordering and workshop records.

Gearing Strategy: Choosing the Right Tooth Count

The tooth count you select has a direct and measurable effect on how your BMW HP4 or S1000RR behaves. Understanding the trade-offs lets you extract the most from Sitta's broad 37-47 tooth range.

A smaller sprocket in the 37-42 tooth range shortens overall gearing, raising top speed and reducing engine revs at motorway cruise — the preferred choice for high-speed circuits with long straights such as Hockenheim or the Autobahn runs.

Stepping up to 43-47 teeth lengthens the effective gearing ratio, sharpening acceleration out of tight corners and making the bike feel more agile through technical sections. This is the setup favoured on shorter, more technical circuits or for riders who want a more responsive throttle on twisting roads.

With eleven discrete options, the Sitta 204Y lets you dial in the precise character you need rather than accepting a compromise.

Construction & Finish Quality

Sitta manufactures the 204Y from high-quality aluminium, balancing structural integrity with the lowest possible rotational weight. The anodising options are not merely cosmetic: hard-anodising in particular creates a surface layer that is significantly harder than standard anodising, extending service life when the sprocket is used hard on track. The remaining seven colour finishes — silver, black, red, blue, gold, orange, and green — are standard anodised and offer a clean, corrosion-resistant surface suited to road and occasional track use.

Fitment & Compatibility

The Sitta 204Y rear sprocket is designed exclusively for the following BMW models equipped with the 520 pitch chain conversion:

• BMW HP4 (all years)
• BMW HP4 Race
• BMW S1000RR fitted with HP forged wheel

Carrier specification: 70/100-5 hole. This sprocket is compatible with 520 pitch chain only. Confirm your chain pitch before ordering.

Specifications