Some help please (gears)

[Mountain-Goat]

Hi guys.

I am just wanting to know if what I am planning to do will work. Can I use a 9 speed crankset with 8 speed chainrings to be run with an 8 speed groupset. So I am wanting to out new 8 speed chainrings on a 9 speed crank arm. Would it be the same as putting 8 speed chainrings on an 8 speed crank arm ?

 

All advice would greatly be appreciated.

[JXV]

So I am wanting to out new 8 speed chainrings on a 9 speed crank arm. Would it be the same as putting 8 speed chainrings on an 8 speed crank arm ?

 

All advice would greatly be appreciated.

I assume the BCD of the 8 and 9 spd chainrings is the same?

8 spd chain is wider than 9 spd so there is a chance the spacing of the chainrings would be narrower on the 9 spd crank in which case you could have issues with the spacing of the FD positions. I'm sure someone who has actually tried it will let you know.

[Mountain-Goat]

I assume the BCD of the 8 and 9 spd chainrings is the same?8 spd chain is wider than 9 spd so there is a chance the spacing of the chainrings would be narrower on the 9 spd crank in which case you could have issues with the spacing of the FD positions. I'm sure someone who has actually tried it will let you know.

Yep same BCD

[johanpre44]

Maybe just measure the thickness of the chainrings. I will not be surprised if the are exactly the same thickness. I also suspect that the distance between the chain rings (which is set by the spider on the crank) is possibly the same.

 

I used to run an 8 speed drivetrain with 9 speed crankset (still with 9 speed chainrings) and had no problems. Struggled a bit to get the 9 speed front derailleur not to rub the chain. 

[King_Crispy]

7, 8 and 9 speed from what I recall, are the same.

Only 10 and 11 speed are narrower

[Captain Fastbastard Mayhem]

7, 8 and 9 speed from what I recall, are the same.

Only 10 and 11 speed are narrower

Winner wena!!!