When Sheldon Brown wrote his page about Shimano cassettes, Shimano had offered only a few cassette body types. Now there are several more. This page will help you identify them and discover compatibilities with hubs and sprockets.

Compatibility with hubs depends on the type of splined or threaded attachment to the hub, and the clearance for the axle: a large-diameter thru axle requires a larger opening in the cassette body. In the table below, cassette bodies used with 3/16" or 5/32" balls are for hubs with (larger-diameter) thru axles.

Most but not all Shimano cassette bodies are compatible with the same series of sprockets. Exceptions are the Capreo, the Dura Ace 7850 with aluminum body, also the Micro Spline 12-speed freehubs, which achieve a very wide range by the use of a 10-tooth smallest sprocket and an inner sprocket as large as 51 teeth.

Freehub body length depends on the number and thickness of sprockets. Common lengths from base of the splines that hold the sprockets to the outer end of the freehub body are

• 24mm -- 5-sprocket (5.5mm sprocket spacing)
• 29,5mm -- 6-sprocket (5.5mm sprocket spacing)
• 30.9mm -- 7-sprocket (5.0mm spacing)
• 34.9mm -- 8, 9, 10 sprocket, 11-sprocket MTB
• 36.85mm -- Dura-Ace 10-speed aluminum body, 11-sprockets road.

The image below shows how this is measurement is taken. The cassette space of both of these 7-speed Freehub bodies is 31mm long. The body on the left has external threads for a threaded Uniglide outer sprocket. The body on the right is a Hyperglide C body which can take an 11T outer sprocket. The measurement is to the outer end of the Freehub body, not to the outer end of the splines.

Some nonstandard options:

A 7-speed cassette may be installed on an 8-9-10-speed body by adding a 4mm spacer.

• an 8, 9 or 10-speed cassette may be installed on a 7-speed body by leaving off one sprocket. If this is the smallest or largest sprocket, shifting is not affected.
• An 8-speed cassette, maybe also a 9- or 10-speed cassette, may be installed on a 7-speed body if the innermost sprocket is dished. or the back of a multiple-sprocket spider is machined down. This only works if there is enough clearance so the rear derailer does not strike the spokes -- so it works better with a larger innermost sprocket.
• An 8-9 or 10-speed cassette may be installed on an 11-speed body with a 1.85 mm spacer behind the largest sprocket.
• An 11-speed road cassette may be installed on an 8-9-10 speed body after machining down the back of the spider for the largest sprockets. 11-speed MTB cassettes already have the 1.8mm cutout and will fit an 8-9-10-speed body.

There are so many different models of Shimano Freehubs -- well over 100 -- that we can list only representative cassette bodies of each type. Many newer cassette bodies are for hubs with thru axles. When a thru axle is thicker, the bearing balls most be smaller to fit inside the Freehub body.

To search Shimano's site for Freehub bodies with thru axles, run this search. Results run to two pages. Then select EV only for parts lists, and model as the sort key. This will place the Freehubs together and you may click on the links to bring up parts lists. Each parts list gives compatibilities with one or two other hubs, but there are additional compatibilities when, for example, changing to a cassette with a different number of speeds. You may run a similar search on a different characteristic, or the name of a product line.

Shimano 7-8-9-10 speed cassettes fit many other brands of hubs, but the cassette body attachment to the hub is different. For some, the body is not removable.