Chainring Help: HaiBike FatSix Bosch >16T?


Active Member
Hey all,

Does anyone know if a 18T or 20T HaiBike XDURO Bosch chainring for the FatSix is to be gotten anywhere? I have no idea were to ask. My FatSix's 16T has no obvious manufacturer's model # on it to delineate it from the standard chainring.

My DEEP chainring:

Standard shallow chainring.


I know much about this as I have work on this type of bike. The Fat 6 with Bosch motor has a special gear and cranks made just for just this bike. While the factory gears may fit the 2nd gen Bosch motor. This gear on your bike is offset for the chain line fitment. One idea might be to contact Felt and see if they use a special gear that has the same offset. As I have heard they use a few different sizes of gears. Otherwise I highly suggest a new rear gearing like a 11-42 11 speed m7000 or above Shimano setup. Now realize the software of the bike only allows for a 10 tooth rear gear change. Any front gear change may require a software change for any Bosch powered bike. Otherwise it might trigger a software issue that may provide less smooth power to the motor. Now shops with Bosch dealer dongle can change some gearing to an extent but it requires a lot of math and understanding of gearing. Many shops wont spend the time to figure that out. I hope that explains a few things to help with your problem.


Active Member
Hey Disraeli!

Thanks for the excellent input, and apologies for the delayed response. I haven't had time to research the possibility of Felt being able to assist, but will do so soon. It's been mildly frustrating to be limited to the FatSix's 16(1.44):10 ratio; two more teeth, and I'd be in Heaven. I'm fortunate to have access to a precision machine-shop, and am considering a custom adapter/extender for the standard 18T. I'll post my results here IF it comes to fruition.

On a lighter-note: is "Disraili" your actual name? Made me think of "Disraeli Gears" and I thought it appropriate to my post's subject!

Correct My spelling is a bit different. As well the Cream album spelling is another different spelling.

I think a custom setup is you best option but Felt is a good place to ask to make sure there are no other options. The Haibike chairing is unique to Haibike only so if you found something else. It would look different and likely be a bit louder. As the thick thin part of the chain ring is under patent with Sram. Post up what you end up doing.