Chain line problems unable to shift to 9th gear

[Paige]

I am a newbie pedelec, but not new to biking. I have a Bafang 750W mid drive, 44t chain ring with a 48V battery that was installed on an Iboc SX Mongoose mountain bike with shimano deore xt rear derailuer. From the get go, I was having problems with not being able to shift into 9th gear, slippage at 7-9th gear. I have had cog wheel replaced, chain replaced, and freewheel hub repacked and tightened, but I am still unable to shift to 9th. This bike has an aluminum frame and is older model and I am wondering if the frame may have too much flex for the power. Any suggestions? I bought the bike from a friend who installed a lot of high end gear and did not ride it much, but says it shifted fine before. I am about ready to pull motor off, and buy a new Specialized Cross Trail. Thanks

 

[Emo Rider]

I am a newbie pedelec, but not new to biking. I have a Bafang 750W mid drive, 44t chain ring with a 48V battery that was installed on an Iboc SX Mongoose mountain bike with shimano deore xt rear derailuer. From the get go, I was having problems with not being able to shift into 9th gear, slippage at 7-9th gear. I have had cog wheel replaced, chain replaced, and freewheel hub repacked and tightened, but I am still unable to shift to 9th. This bike has an aluminum frame and is older model and I am wondering if the frame may have too much flex for the power. Any suggestions? I bought the bike from a friend who installed a lot of high end gear and did not ride it much, but says it shifted fine before. I am about ready to pull motor off, and buy a new Specialized Cross Trail. Thanks

Firstly, have you have a bike shop have a look at the limit scew settings and cable adjustment?

Secondly, did you have the cassette replaced at the same time as the chain?

Finally, is you gear shifter on your handle bar Shimano or Sram?

Cheers

 

[Fordulike]

I am a newbie pedelec, but not new to biking. I have a Bafang 750W mid drive, 44t chain ring with a 48V battery that was installed on an Iboc SX Mongoose mountain bike with shimano deore xt rear derailuer. From the get go, I was having problems with not being able to shift into 9th gear, slippage at 7-9th gear. I have had cog wheel replaced, chain replaced, and freewheel hub repacked and tightened, but I am still unable to shift to 9th. This bike has an aluminum frame and is older model and I am wondering if the frame may have too much flex for the power. Any suggestions? I bought the bike from a friend who installed a lot of high end gear and did not ride it much, but says it shifted fine before. I am about ready to pull motor off, and buy a new Specialized Cross Trail. Thanks

If the chainring is the original Bafang one that came with the kit, then you may need to purchase a custom chainring with more offset.

The original on mine gave a poor chainline, so I fitted one of these:

http://www.alcedoitalia.it/en/accessori-bafang-bbs/216-corona-42-denti-per-bafang-centrale-bbs01-e-bbs02.html

A Lekkie Bling Ring will also do the trick:

http://www.brightonebikes.co.uk/store/c11/Lekkie®_Bling_Rings.html

 

[Paige]

Firstly, have you have a bike shop have a look at the limit scew settings and cable adjustment?

Secondly, did you have the cassette replaced at the same time as the chain?

Finally, is you gear shifter on your handle bar Shimano or Sram?

Cheers

Yes, a bike shop replaced chain and cassette, aligned the deraileur, indicated no bends, and adjusted limit screws all at the same time. This was not done again after the freewheel hub was repacked and tightened. I wondered if it might need to be realigned after this repair. I performed some slight adjustments that corrected some slippage, but did not enable me to shift to 9th gear.

 

[Paige]

If the chainring is the original Bafang one that came with the kit, then you may need to purchase a custom chainring with more offset.

The original on mine gave a poor chainline, so I fitted one of these:

http://www.alcedoitalia.it/en/accessori-bafang-bbs/216-corona-42-denti-per-bafang-centrale-bbs01-e-bbs02.html

A Lekkie Bling Ring will also do the trick:

http://www.brightonebikes.co.uk/store/c11/Lekkie®_Bling_Rings.html

Thank you, but I am leary to go with such a small ring. I have a 42T and already feel like I am simply not getting enough torque. I commute 30miles roundtrip on a fairly rolling road and when I am pedalling in 9th gear with my 42T on eco pas 2 going down hill I can't even pedal because there is not enough torque. I have read about problems with not enough offset and hitting gears 1 and 2, but those are no proble. Do you think this could also be problem for 9th gear? Do you know if they have anything larger than a 32? I plan to look deeper after work.
thanks

 

[Paige]

Firstly, have you have a bike shop have a look at the limit scew settings and cable adjustment?

Secondly, did you have the cassette replaced at the same time as the chain?

Finally, is you gear shifter on your handle bar Shimano or Sram?

Cheers

Not sure if bar shifter is Sram or Shimano. Don't see a name on it. Will try to look on back.

 

[Fordulike]

Thank you, but I am leary to go with such a small ring. I have a 42T and already feel like I am simply not getting enough torque. I commute 30miles roundtrip on a fairly rolling road and when I am pedalling in 9th gear with my 42T on eco pas 2 going down hill I can't even pedal because there is not enough torque. I have read about problems with not enough offset and hitting gears 1 and 2, but those are no proble. Do you think this could also be problem for 9th gear? Do you know if they have anything larger than a 32? I plan to look deeper after work.
thanks

Yeah sorry my bad, the custom chainrings usually help with problems in lower gears. Must've had a brain fart lol.

Not quite sure what you are on about with the torque though. The smaller the chainring on a BBS02, the greater the torque at the rear wheel in every gear.

The hill climbing ability of my bike increased dramatically by changing from a 48T to a 42T.

You need to think about programming the BBS02 controller, if you find it lacking in performance.

Take a look here: https://electricbike-blog.com/2015/06/26/a-hackers-guide-to-programming-the-bbs02/