Call Us: 01782 747782
Free UK Shipping Over £50 & Easy Returns




Free UK standard shipping on orders over £50
Enhance your cycling drivetrain with the SunRace MZ903 12 Speed Cassette, engineered for precision and reliability. Designed specifically for Shimano 12 speed transmissions, this cassette delivers smooth and consistent shifting performance, ensuring a seamless ride across diverse terrains. Its robust construction featuring alloy spacers and a lockring guarantees long-lasting durability, making it a dependable upgrade for your bike.
With a versatile 11-51 tooth range, the SunRace MZ903 provides optimal gear ratios that accommodate both steep climbs and fast cruising. Whether you are tackling challenging hills or enjoying extended rides, this cassette enhances your drivetrain’s efficiency and responsiveness. Explore more options within the Bike Parts category to complement your setup.
Is this cassette compatible with all Shimano 12 speed bikes?
The SunRace MZ903 is optimised for Shimano 12 speed transmissions; however, it is recommended to verify compatibility with your specific bike model before purchase.
What key accessories or add-ons complement this model?
Consider pairing this cassette with compatible pedals, helmets, and lights to enhance your overall cycling experience and safety.
Stock Status Instock - Instore - Item Usually shipped or available for shop collection, within 48 hours (Mon-Fri)
Instock - Supplier Warehouse - Item is held in Suppliers Warehouse, Depending on the the supplier transfer time can vary from 24 Hours to 14 Days for item held in European warehouse.
(over festive periods some suppliers shut from 24th Dec-2nd Jan so orders can be delayed through this period.)
Brands held in European website include Trek, Bontrager, Electra, Wahoo, Rapha. For up-to-date transfer times please call customer services on +44 (0)1782 768622
Most out products are shipped by FedEx, providing unprecedented reliability and speed. Lightweight Spares below £25.00 value have a Royal Mail postage option, which is sent via Tracked 48 service. - £2.99
Shipping on all Domestic Orders over £50.00 (excluding bikes and home trainers) for delivery within the UK is completely FREE!
Bike and Home Trainers and oversize Goods £15.00 - FedEx
White Glove Bike Delivery - our white glove option has your bike personally delivered to you by a fully trained Mechanic and Bike fitter - £99.99
(Certain bikes will only have this option such as Cargo Bikes)
To Qualify for FREE Shipping:
In some cases, we may ship items out with another courier, depending on the status and availability of items ordered. (Customers will not be charged more and will be refunded any unused postage cost) If part of an order is cancelled and the total drops below the £50.00 free postage, a postage charge may be taken.Â
Delivery costs will be clearly stated on the checkout page, though you will need to register (to provide your delivery address) in order to see the delivery costs.Â
If you have any questions about delivery charges, times or none delivery please do not hesitate to get in touch by email:store@swinnertoncycles.co.uk or by telephone on +44 (0)1782 768622. Handling is normally 48 hours, but at busy periods this may be extended but we will endeavor to process your order within 5 working days. Please bear in mind in some cases orders can take longer to process, please contact us for more details.
You may return most new, unopened items within 30 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.

