5- and 6-speeds used 3.65 mm spacers, 7-speed generally 3.15 mm, 8-speed 3.0 mm. Spacer washers would fit between each pair of sprockets. The oldest Shimano cassette sprockets used a 'twist-tooth' design, called 'Uniglide.' They had 9 identical splines (tabs) that would slide into matching grooves on the Freehub body. This tool is of vital importance for a bicycle tourist.Īfter replacing the cassette, the lockring should be tightened until it is snug, but not tightened with gorilla-like force - especially not if it may have to be removed on the road. To remove the lockring, you need to turn it counterclockwise, but then the cassette will freewheel, so you need a chain whip to hold the cassette.Ī special tool is available to remove and retighten the lockring on the road, using the bicycle's frame and chain to provide leverage. The lockring has a normal right-hand thread: turn clockwise to tighten it. Some lockring tools have a long handle, others, like the one in the photo below, have a hexagonal fitting like a nut, which can either be turned with a large wrench or clamped in a vise. There is a special splined tool that fits the notched hole in the lockring. Modern Hyperglide-type cassettes (everything made since the late 1980s) use a threaded lockring to hold the sprockets onto the splines of the Freehub body. This saves weight, but sprockets that come mounted on a spider cannot be interchanged except as a complete unit. Some of the high-end cassettes use a 'spider', an intermediate metal casting, to hold 2 or more of the largest sprockets. These bolts or rivets are by no means necessary, they just make it easier to keep the sprockets and spacers in the correct order and position when they are removed from the ratchet body. Sprockets in many cassettes are held together by three small bolts or rivets for ease of installation.

The sprockets are commonly sold as a set, called a ' cassette'. There is no need to remove the ratchet mechanism. With a Freehub, on the other hand, once the sprockets are removed, the right hub flange is accessible for replacement of a broken spoke.

Removing a freewheel is a chore, because pedaling tightens it onto the hub threads. When you wear out the sprockets on a Freehub, you replace the sprockets only, not the ratchet mechanism (which typically lasts much longer than the sprockets). The Freehub incorporates the ratchet mechanism into the hub body (although the ratchet mechanism is still replaceable).

Origin 8 freewheel