Help! Incorrect motor?

[Copperslip]

Hi all,
I've just purchased a new Chinese SMLRO E7 20" fat tyre bike, though impressed with the general quality I have noticed the geared hub motor is for a 26" wheel, not the 20" wheel as fitted to the bike. My understanding is small wheel geared hub motors give higher torque and rpm than larger wheels as the windings are different per wheel size. Customer services have told me these motors are fitted to many different size wheels. Am I right to complain or is it you get what you paid for. Many thanks in advance.

 

[saneagle]

Hi all,
I've just purchased a new Chinese SMLRO E7 20" fat tyre bike, though impressed with the general quality I have noticed the geared hub motor is for a 26" wheel, not the 20" wheel as fitted to the bike. My understanding is small wheel geared hub motors give higher torque and rpm than larger wheels as the windings are different per wheel size. Customer services have told me these motors are fitted to many different size wheels. Am I right to complain or is it you get what you paid for. Many thanks in advance. View attachment 54639View attachment 54641

The 26" wheel motor would be better than the 20" one because it'll run more efficiently and give more torque at legal speeds. You can only complain if the bike doesn't do or isn't what the listing says.

 

[Sturmey]

Hi all,
I've just purchased a new Chinese SMLRO E7 20" fat tyre bike, though impressed with the general quality I have noticed the geared hub motor is for a 26" wheel, not the 20" wheel as fitted to the bike. My understanding is small wheel geared hub motors give higher torque and rpm than larger wheels as the windings are different per wheel size. Customer services have told me these motors are fitted to many different size wheels. Am I right to complain or is it you get what you paid for. Many thanks in advance.

Hi. As a matter of interest, what is the actual outside diameter of the wheels tyre when measured with a ruler or tape? I ask this because I have seen one fat tyre bike with 20 X 4 tyres that measured close to 24 inches outside diameter.

 

[saneagle]

Hi. As a matter of interest, what is the actual outside diameter of the wheels tyre when measured with a ruler or tape? I ask this because I have seen one fat tyre bike with 20 X 4 tyres that measured close to 24 inches outside diameter.

Good point, well presented.

 

[Copperslip]

Good point, well presented.

Outside Diameter is close to 23 inches, I did notice in display settings wheel diameter was set to 26 so I changed it back to 20. Not sure if this was the correct way to go.

 

[joelectric]

Nice bike, like the low step frame.
With that motor setup up you'll be flying up the hills.

 

[Benjahmin]

The wheel size setting is there to facilitate speed read out. A smaller wheel will go more rpm/mile than a larger wheel, therefore changing it to 20" means the mph display will be low, if set to 26 it will be high. You're sort of stuck in the middle, does it have a 24" setting?
The other thing wheel size setting may affect is cut off speed. Legally this should be 15.5mph. If registration of speed, via wheel size setting, is adrift, so will cut off speed be.
Guess the only way to check it for accuracy would be with an independant gps device.

 

[Copperslip]

The wheel size setting is there to facilitate speed read out. A smaller wheel will go more rpm/mile than a larger wheel, therefore changing it to 20" means the mph display will be low, if set to 26 it will be high. You're sort of stuck in the middle, does it have a 24" setting?
The other thing wheel size setting may affect is cut off speed. Legally this should be 15.5mph. If registration of speed, via wheel size setting, is adrift, so will cut off speed be.
Guess the only way to check it for accuracy would be with an independant gps device.

Many thanks for your advice Benjamin, I'll set the wheel size to 24", luckily my display will change wheel size in increments of .1 of an inch so I can use the GPS speed on my phone to verify and adjust accordingly.