Bicycle Freehub Wear Damage: What to look for

The external body of the freehub (freehub body) can wear depending on the freehub material. This is a concern when doing maintenance on your bike freehub and especially when buying new wheels.

Freehubs come in both alloy and steel. Some prefer alloy because of its lightness. Many of today's cassettes are made of individual cogs with small spines. What happens to an aluminum freehub body when using an inexpensive cassettes (which is usually steel) with many free cogs is that the thin spins of the low gear sprockets dig into the splines of the cassette. The lowest gears have the greatest amount of torque applied. If left on long enough the cassette/sprockets can be troublesome to remove. For these alloy cassettes such as those used a mountain bike or road bike freehub, One solution is to go with one of SRAM's top of the line one-piece cassettes such as the Red XG-1090 or XG-1190. These cassettes are machined, at least in part, from a single piece of steel and utilize an alloy large cog to interface with the freehub body. The spline on the cogs is wide and soft, so it doesn't dig into alloy freehub bodies. My only objection is that SRAM is that their pricey and now making most of their one piece "Red" cassettes only in 11 speed. Also the largest cog on some is reinforce alloy, which some complain wears very rapidly.

I prefer steel or titanium free hubs. The weight difference is only a few hundred grams more which makes little difference to the bike enthusiast. Most Shimano freehub are made from either steel or titanium, and both materials will hold up well to free floating cogs. White Industries also uses titanium freehubs for a gouge free setup. Mavic freehub has always been steel. Chris King has a steel freehub option for many of their hubs, and a lot of companies are developing hybrid systems similar to American Classic, where there is a steel reinforcement added to a few of the splines on an alloy freehub body in order to get the best of both worlds.

Three important points to keep in mind:
1. Match both the chain and cassette to that of the derailleurs (this is especially important when running 11 speed).
2. Go with the highest level that is reasonable priced. With the higher levels, the larger cogs are usually made of a single steel unit which will distribute the torque (which is greater with the large cogs, i.e. lower gears) over a greater area with less "pitting" to the freehub body.
3 .Don't forget to lightly grease the spines of the freehub before installing the cassette!

With this knowledge of freehub wear, you should be able to make a knowledgeable choose in hubs and know what to look for when doing maintenance or you replace freehub or change freehub.