The Difference Between a BMX Freecoaster and a Cassette
Last Updated on March 25, 2020
This guide has been written by cycling review expert Alex Bristol
A freecoaster, unlike a cassette for a BMX, does not require pedalling to go backwards. This usually makes performing certain tricks or stunts on a BMX significantly easier due to the lack of having to multitask.
A cassette and a freewheel function identically. They actually both allow freewheeling, which means you can coast when going forward. The main difference between the two is that a cassette is splined and fits centrally on the freehub section of the hub, but the freewheel usually threads directly onto a hub body. It’s worth noting that a higher price is usually consistent with free coasters due to their complexity.
The moving parts inside a freecoaster do not come without issue as they are less consistent than cassette hubs and skip or jam up far more frequently.
How a freecoaster works
The normal freecoaster functions from a screw-type mechanism. On the hub, there is a driver and this will link a screw into the hub itself. The free coaster has a clutch on the inside, so when the rider starts to pedal, the driver is turned.
The process of this motion from the rider will cause the clutch to move towards the driver. In almost all coasters the clutch is made to not move forward with the driver by a spring inside the axel. This spring plays a crucial role as its main objective is to ensure that the threads of the free coaster driver will pull the clutch in.
When the clutch moves into position, it aligns to one of the many ridges on the clutch and the hub will begin to turn.
When the clutch is in a ridge and the rider is pedalling, the BMX will propel forward due to the driver not being able to slip outside of the clutch.
This allows for the rider to ride the bike normally and leverage a free motion when the bike is not being pedalled. As the rider stops pedalling, the movement of the hub will then push out the clutch from the driver thread to disengage, leaving the driver to be left to glide over the threads as the hub and axel continues to move.
Some users complain about the slack on a free coaster and this is down to a rational gap in the clutch.
This is the slight movement between the driver hitting the closest ridge on the clutch. The reason why there is a greater amount of slack in because a normal cassette with take up to a 20th of a turn to engage, whereas a free coaster could take a 10th of a crank turn, thus causing a bigger delay in engagement.
Image courtesy of // bmxunion.com
How a BMX cassette works
With a cassette hub on your BMX, you’ll notice that when your bike moves backwards the pedals begin turning the opposite way to which you usually pedal.
As the wheels turn backwards, so will the cranks. This is a particularly easy way to understand the difference between a free coaster and a cassette.
A cassette is a hub that can be recognised by it’s clicking sound when the bike is propelled forward. This sound is created by the pawls on the freewheel hitting the splines inside the hub when the wheel is turned.
The click comes from the passing over of the engaged surfaces. As the pawls are always in contact with the splines, the pedals of the bike will always be engaged when the hub rotates the opposite way to which a rider pedals.
The better the build quality of the cassette hub, the stronger the material inside meaning that there is a louder sound that comes from the bike when moving. We notice this on more higher-end, top quality bikes.
Whilst a cassette hub engages quicker, sometimes riders have to find the perfect feet positioning to perform a jump or stunt. If you don’t have the perfect feet alignment riders would have to pedal a little extra to get their feet to a comfortable position to carry out the jump or trick. This can be a particularly big ask, especially if you’re already halfway over an obstacle or on a ledge.
If you land with your feet in the wrong position, it makes it harder to land backwards and begin to rotate the cracks anti-clockwise.
1. What is the difference bettween a freewheel and a hub – Question on Stack Exchange