Motorcycle Bearing

A motorcycle uses standard bearings in more places than most riders realise: two or three in each wheel, one in the rear sprocket carrier, several in the engine and gearbox, and a pair in the steering head. Most of them are single row deep groove ball bearings from the 6000, 6200 and 6300 series. The steering head often uses tapered roller bearings or a cup-and-cone race with loose balls, and the swing arm pivot usually runs on needle bearings or bushes. This page sorts the positions, explains the seal and clearance choices, lists the common sizes and shows how to order the right one.

Motorcycle bearing positions

Position	Usual bearing type	Typical sizes	Seal / lubrication
Front wheel	Deep groove ball bearing, two per hub	6201, 6202, 6301, 6302	2RS, factory greased
Rear wheel	Deep groove ball bearing, two or three per hub	6202, 6203, 6302, 6303, 6004	2RS, factory greased
Rear sprocket carrier	Deep groove ball bearing	6004, 6005, 6204, 6304	2RS
Crankshaft (small engines)	Deep groove ball bearing, often C3 or special clearance	6204, 6205, 6304, 6305	Open, engine oil
Gearbox shafts	Deep groove ball bearing, some needle bearings	6203, 6204, 6303, 6304	Open, engine or gearbox oil
Steering head	Tapered roller bearing or loose-ball race	30202, 30203, 32005, 32006, 32007	Grease at assembly
Swing arm pivot	Needle bearing or bush	Varies by model	Grease

The sizes are typical, not a guarantee for a particular bike. Two models from the same maker can use different bearings in the same position. Always confirm with the number on the old bearing or the parts list.

FULI supplies the deep groove ball bearings and the tapered roller bearings in this table. We do not list needle bearings or loose-ball steering races on this site.

Wheel bearings: 2RS and the spacer

Wheel bearings get the hardest treatment on a motorcycle. They take the weight of bike and rider, the shocks from potholes and the side load in corners, and they sit low enough to get sprayed with water and grit. That is why wheel bearings are almost always 2RS, with a rubber contact seal on both sides. Metal shields (ZZ) let water through, and a wheel bearing that rusts inside starts to grind within weeks.

Between the two bearings in a hub there is a tube spacer. When the axle nut is tightened, the clamping force goes through the inner rings and the spacer, not through the balls. If the spacer is missing, too short or not seated, the axle nut squeezes the inner rings toward each other and preloads the bearings. They run hot and fail early. Before you fit new wheel bearings, check that the spacer is there and that its ends are square.

Fit each bearing by pressing on the outer ring, since the outer ring has the interference fit in the hub. Pressing on the inner ring or the seal pushes the load through the balls and dents the raceways. If the hub bore is worn and the new bearing slides in by hand, the outer ring will turn in service and the hub needs repair.

Engine and gearbox bearings

Engine and gearbox bearings run in oil, so they are usually open. A sealed bearing in that position stops the oil from reaching the balls. Some engine bearings have one shield on the side facing the crank chamber; copy the original exactly.

Crankshaft bearings in small engines run hot and have tight fits on the shaft. They are often C3, and some use a clearance specified by the engine maker. Read the clearance mark on the old bearing; if there is none, check the workshop manual before assuming C0. The bearing internal clearance guide explains the groups.

Crankshaft bearings in some engines also carry a special cage or ring design. If the old bearing has letters after the size that you do not recognise, send a photo of all markings with the inquiry.

Steering head bearings

Older bikes and many small motorcycles use cup-and-cone steering races with loose balls. Many riders upgrade to tapered roller bearings, and many newer bikes use them from the factory. Sizes such as the 30202 bearing, 30203 bearing, 32005 bearing, 32006 bearing and 32007 bearing are common in this position, but some steering head bearings are special widths made only for motorcycles.

A tapered steering bearing is adjusted at assembly: tight enough that the forks do not knock under braking, loose enough that the bars turn freely without notching. Tapered roller bearings usually leave the factory with rust protection only, so they must be greased when installed.

Motorcycle bearing sizes by shaft diameter

The bore is the axle or shaft diameter at the bearing seat. All three series below are available with 2RS seals for wheel positions and open for engine positions.

Shaft d (mm)	6000 series	d x D x B	6200 series	d x D x B	6300 series	d x D x B
10	6000	10 x 26 x 8	6200	10 x 30 x 9	6300	10 x 35 x 11
12	6001	12 x 28 x 8	6201	12 x 32 x 10	6301	12 x 37 x 12
15	6002	15 x 32 x 9	6202	15 x 35 x 11	6302	15 x 42 x 13
17	6003	17 x 35 x 10	6203	17 x 40 x 12	6303	17 x 47 x 14
20	6004	20 x 42 x 12	6204	20 x 47 x 14	6304	20 x 52 x 15
25	6005	25 x 47 x 12	6205	25 x 52 x 15	6305	25 x 62 x 17
30	6006	30 x 55 x 13	6206	30 x 62 x 16	6306	30 x 72 x 19
35	6007	35 x 62 x 14	6207	35 x 72 x 17	6307	35 x 80 x 21
40	6008	40 x 68 x 15	6208	40 x 80 x 18	6308	40 x 90 x 23

All dimensions in mm. Load ratings for each size are on its model page.

For the same bore, the 6000 series is the thinnest and lightest and the 6300 series the heaviest. A 6004, 6204 and 6304 all fit a 20 mm axle but need different hub bores. If your bearing has no readable number, measure it with a caliper and use the bearing size finder.

Signs a motorcycle bearing needs replacing

• Wheel play. Lift the wheel off the ground, hold it at the top and bottom, and rock it. Any knock means a worn bearing or a loose axle.
• Rough rotation. Spin the wheel with the brake pads off. A grinding feel or noise that changes with speed points to the bearings.
• Notchy steering. With the front wheel off the ground, the bars stop in the straight-ahead position instead of swinging freely. This is a dented steering head race.
• Engine noise that rises with rpm and does not change with load can come from a crankshaft or gearbox bearing.

Replace wheel bearings in pairs. The second bearing in the hub has seen the same water and the same shocks.

How to order motorcycle bearings

Motorcycle and scooter parts lists often give an OEM part number instead of the standard bearing number. That is not a problem, but the OEM number has to be matched to the standard bearing it represents before we can quote. Send one of these:

1. The number printed on the old bearing, including suffixes such as 2RS, ZZ or C3.
2. The OEM part number together with bore, outside diameter and width.
3. A photo of the bearing markings and the bearing in place.

The guide on how to identify a bearing model explains how OEM numbers and suffixes are matched. Add the quantity per size and any marking or box requirement: your authorized brand, the factory brand or neutral printing. Send the list to sales@fuli-bearings.com or through the contact page.

Before shipment we check rotation smoothness, dimensions, grease fill, rust and appearance. Deep groove ball bearings are Z3V3 vibration grade as standard, with GCr15 chrome steel rings and balls. An inspection report can cover dimensions, radial clearance, rotation noise, vibration, appearance, material certificate and batch traceability. Export documents are the commercial invoice, packing list and CCPIT certificate of origin, plus an FTA Form COO where the destination country qualifies.

Backed by 20+ years of bearing export experience in Linqing, Shandong. FULI ships to 50+ countries & regions.