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Bike Axle Types & Standards Explained

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The four main bike axle standards are: quick-release (5 mm rod with cam lever, road bikes pre-2018, hybrids); thru-axle 12 mm (modern road and gravel disc-brake bikes, also some MTB rear); thru-axle 15 mm (modern MTB front + some gravel); and Boost 110/148 (wider thru-axle spacing for modern MTB, allowing shorter chainstays and better tire … Read more

Bike Dropouts & Fork Ends Explained: Everything You Need To Know

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Bike dropouts (rear) and fork ends (front) are the slots in the frame and fork where the wheel axles attach. Modern bikes use closed thru-axle dropouts (a circular hole the axle threads through); older bikes use open quick-release dropouts (a slot the axle drops into). Other variants: vertical dropouts (axle slides straight in, common on … Read more

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