Yes, I know, I picked the most trivial (or apparently) subject for my second article on freecoasters. But, I am kind of tired, and am procrastinating reading about ancient America. So, why am I even reviewing this? aren’t all hub shells pretty much the same? No, there is actually a lot to consider when designing a hub shell.
How do freecoaster hub shells differ from others?
Freecoasters use a hub shell that has the basic flanges, bearing seats, and paint/anodizing. The main difference, is that there is no engagement ring on the drive side of the hub shell. However, the difference is that the freecoaster has a steel ring inside where the clutch will run into and engage the hub. This engagement ring can be inserted into an aluminum shell by either pressing it in or threading. Bond the ring to the shell is unlikely without the use of one of the aforementioned processes.
Types of hub shells:
Really, in the world of freecoasters there are only a couple of hub shells. Basically you have the steel, unsealed hub shells and aluminum, sealed shells.
These weigh more than their aluminum counterparts, and cannot be anodized. These are typically manufactured using cheap processes, where the flanges are pressed onto the main body of the hub shell. Old Suntor riders would weld the flanges to the body. Nankai ran with this and produced the two together stock. Even with the setbacks, steel hub shells are stronger, and last longer. They also use a one piece shell body, thus making slipping of the “engagement ring” impossible.
- Strong Bearings
- Strong shell (when welded
- Require modifications on cheaper hubs to make them work well (not including Nankai)
- Cannot be anodized, so it must be painted or chromed (which is not as aesthetically pleasing)
Aluminum shells are lighter, look cleaner, and typically run sealed bearings (for less maintenance). Most aluminum shells are machined on a lathe, then either press or thread in a steel ring for the clutch to engage the hub. These are the more modern idea for shells, and what a wonderful change. The last great thing is that they can be anodized, so you can get some truly wonderful colors.
- Can be quite nice looking
- Much less maintenance than the unsealed conterparts
- Weaker flanges
- Weaker bearings
- Require pressed in engagement ring
Profile Aluminum Nankai Shell
Last year profile released their aluminum, anodized hub shells for the Nankai freecoaster. This little after market advancement drops four ounces off of the steel hub shell. In order to make it work with an unsealed bearing races were pressed dirrectly into the hub shell (similar to the engagement ring ).
- Strong bearing interface
- Wide variety of beautiful colors
- Uses the infamous Nankai internals
- Requires more maintenance
Essentially there are two types of engagement rings. Either it can be a piece of a steel shell, or it can be a steel ring pressed or threaded into an aluminum (or magnesium) shell. Between the two, there isn’t too much of an advantage as long as both are made properly. Steel 1 piece shells transfer energy more efficiently, so they can feel very incrementally more solid in engagement. The real purpose for this little section is to talk about the shape of the ring. When taking apart my Odyssey hub, I noticed that only a little bit of the clutch engages at any one point, only hitting a corner. this caused odd deformation in the engagement ring. This deformation caused inconsistent engagement. My new Nankai, however, uses an angled one, even in the profile shell. This makes a much larger area of contact between the clutch and engagement ring. It feels solid, and smooth. Hopefully it will stay that way. I have not checked on the Geisha or others, so let me know if you guys find out about those.
Steel: The classic. Strong, heavy, and sometimes chrome
Aluminum: Light, Pretty, fairly strong, the modern pick.
Titanium: Completely overreaching. Ti is not the right material for this purpose. It is too soft, and is more expensive than people will pay for it. Anyway, the money should be going into the internals instead of here. On the upside, it can be made very light.
Carbon fiber: These have been done on a lot of road hubs. They are very strong, but are expensive. Carbon is also very sensitive to corrosion, so the greases in a freecoaster would eat the hub alive.
Magnesium: This was used on the Proper Magnati hubs. It can be a good idea if the materials tolerances are kept up to par. Magnesium is a porous material, so there are often a lot of inconsistencies. This can be made pretty light, but it may have corrosion issues like the carbon.