Sunrace 8-Speed Freewheel

Product Information

Shimano lists Freehub bodies as a separate part, or you could cannibalize a hub. Wheels with damaged rims and good hubs are not hard to find. Within a given brand/style of rear derailer, all "speed numbers" are generally interchangeable. This applies to all indexable models, basically everything manufactured since the late 1980s. There are a few exceptions: The foot power is very considerable, and that's why it can be so hard to remove a freewheel that has been used for a while, especially on a bike with low gearing. To prevent future difficulty with removal, it is very important to grease the threads before screwing a freewheel onto your hub!

Leave the freewheel in place on the wheel, or screw it onto a wheel, so that you will have something to hold it with. Breaking the freewheel loose from the wheel now with a freewheel remover reduces the likelihood of damage to the inner body if you have to remove it for reassembly. (If you don't have the right freewheel remover, or the remover splines on the freewheel are munged up, it is useful last resort to grab the inner body in a vise to remove it, after disassembling the freewheel.) Mountain" hubs will likely be slightly better sealed against dirt and mud than "road" hubs, but this is rarely an issue in practice. The wider 135 mm spacing will generally result in a slightly stronger wheel due to reduced dishing of the spokes.

Cassette sprocket-tooth widths

SpeedsIn the 1980s, these two approaches were combined to create 7-speed freewheels, with 5 mm ("Ultra") spacing that would fit the same 126 mm hubs as "standard" 6-speeds. Although "Road" and "Mountain" hubs are no different as far as cassette fitting is concerned, they are different in terms of overall spacing. "Road" hubs generally use 130 mm spacing, while "mountain" hubs are 135 mm. Early Hyperglide hubs had both external and internal threads, so they would work with either style of cassette.

Your Sugino may be 110mm bcd, in which case it will accept an inner ring down to 34 tooth. If 130 bcd, then a 38 is available, or 39 if 135 bcd. SRAM "ESP" or "Exact Actuation" derailers and shifters (generally designated by a decimal model number: 7.0, 8.0, 9.0 etc) can only be used if the shifter and rear derailer are both ESP. A Jtek ShiftMate pulley adaptor can make a SRAM shifter work with a Shimano derailer, or vice versa. All SRAM 10-speed derailers and shifters are of yet a third type. FH-7850 and FH-7900 Dura-Ace bodies, which have returned to a splined attachment between Freehub body and hub shell, but it is larger than the usual one. It is similar but not interchangeable between these two models. Shimano information on the 7850; 7900. Narrow chains bring other problems, though. They are usually more expensive and -- with 10 or more speeds -- don't last as long -- even when used in the intended system. Campagnolo made a very slight change in indexing in 2001. Supposedly, you need to use 2001 or later shifters with 2001 or later rear derailers, but the difference is so small that it doesn't matter in practice.Shimano wants you to use one of its standard combinations, and offers a wide-enough choice to suit the needs of most cyclists, but you don't have to if you don't want to! The Shimano Hyperglide cassette body has become a de facto industry standard. Many other manufacturers make hubs and cassettes that are compatible with Shimano. There are exceptions and partial compatibilities. Some of the other manufacturers offer cassette bodies to fit different brands and models of cassettes. An additional complication is that "road" front derailer cages are shaped to fit well with a 52-53 tooth big chainring, while most current "mountain" front cages are shaped to fit with a 42-44 tooth big ring. These chainrings have the teeth slightly farther to the right than the older chainrings to work a little better with the narrower chains. There is no difference whatever in the crank spiders. Although the most common Shimano bodies are interchangeable at the hub shell, you may have further complications due to incompatibility between your right side cone and the dustcap that comes with a replacement body. The dustcaps can usually be pried out and interchanged, or you can buy an appropriate right cone to match your new ratchet body.