Which chainwheel to choose

[bops]

Hello

I have a Romet Vintage mens city bike which I would like to turn into a e-bike using Bafang BBS02B 750W mid drive motor but the chainwheel on my bike is 38T and the smallest chainwheel that psw power have to offer is 44T and they responded me that I need to choose 38T. So the question is, can I use the chainwheel that is already on my bike or can I use the 44T which comes with the motor?

Here is a picture of my bike: https://hh2.pigugroup.eu/colours/14...pyora-tummansininen-runko-9087f_reference.jpg

Would appreciate of any help

 

[kmccune]

Maybe have to lengthen chain a bit, no reason you cannot use 44 tooth chain ring, it will speed you up a little through the range.They are only going to tell you the easiest most reliable mod to use( less comeback and having to deal with irate purchasers whom the product was less than satisfactory, just one thing, do you need the power of that BBSO2? Would a hub drive with a built in controller be enough for you?

 

[Reclyndrider]

Those bafang chainrings are very specific to the final drive of the motor. The hole in the center where your crank shaft goes and five screws around that hole to fasten the bafang chainring to the drive. Pictured is the 46T that came with this motor. Notice the chainring has a slight offset. Hope this helps you.

 

[munirider]

Amazon.com

This is the only chainring that I have found for the bbso2 with offset. The 38 tooth sprocket that you would get is flat and your chain alignment will be terrible, and you won't be able to use your lowest gears with it. Stick to the 44 tooth that comes with or buy this DERUIZ chainring

 

[bops]

Thanks for the replies. I was thinking how the chain will adjust to the bigger chainwheel but didnt realize I can lenghten the chain. I will go with the 44T and see what happens. The reason Im buying 750w motor is that its the same price than 250w and 500w, so why not go for it

 

[Chuy]

In the pic, the chain is on the largest cog and the derailleur still has room to adjust, so you may be able to use the same chain. The important thing is maintaining the same chain line. That is a nice bike. The biggest drawback I see are the rim brakes. But if you are not a speed demon, it should work out.