Don't the 5 holes already on their chainrings match up?jpo wrote:Since this is a DIY web site I thought I would suggest a cheap alternative. I've taken cheap steal chain rings from sick bike and drilled 5 holes in them to mount directly to the motor. Some care must be taken when drilling the 5 holes but it does work. There is a down side and potential issue. The center hole on the sick bike chain rings is larger than the center hole on the stock bafang ring so all of the load goes to the 5 screws attaching the chain ring to the motor. This could eventually snap the screws. I have not had a problem in 200 miles but beware I have detuned my bafang to a max of 800 watts and typically ride between 400 and 600 watts. The 750 at full strength could be an issue as it can pull well over 1000 watts
I use mine with a 9 speed cassette and the chain line is ok not great but it shifts fine and chain does not fall off. I am using a front derailleur as a gauge to keep the chain from falling off.
Can you post a pic of yours?
I am hoping that I can run a bafang 44t on sick bikes HD freewheel screwed onto my hub motor... don't know if they will match for now... if they don't then the 44t will go at the front and I'll have to order a chainring from them for the back....
Hope the torque isn't too much for the screws as you mentioned.
Does their 36t offset inwards clear the "bafang sticking out bit" on the bottom right of the motor?