Bicycle Mechanics - Milling a 9 speed crank to 10 speed

I recently acquired a 9 speed Ultegra crank real cheap but would like to run 10 out back. I've searched everywhere and it seems i could probably run as is, but if i wanted to do it right, how much would i mill off the spider for the distance between center of rings to be correct for a Shimano 10 speed? The crank is a double. I guess all i really need to know is the difference in spider thickness between the two? If someone has a set of calipers and a 10 speed crank without any rings on it could you let me know the width? Also i suppose with some creativity and a rotary table i could fix the rings themselves, anyone know the width and pitch of the 10 speed teeth?

Thanks for your time

The difference is .6mm. Have fun with the lathe

I recently acquired a 9 speed Ultegra crank real cheap but would like to run 10 out back. I've searched everywhere and it seems i could probably run as is, but if i wanted to do it right, how much would i mill off the spider for the distance between center of rings to be correct for a Shimano 10 speed? The crank is a double. I guess all i really need to know is the difference in spider thickness between the two? If someone has a set of calipers and a 10 speed crank without any rings on it could you let me know the width? Also i suppose with some creativity and a rotary table i could fix the rings themselves, anyone know the width and pitch of the 10 speed teeth? It will work fine.

Milling the spider would be a Very Bad Idea, the spider thickness is the same for all of them. The difference, such as it is, is in the smaller chainring, which has the teeth offset very slightly to the right.

My very strong advice is to try it as is, before messing with it.

Sheldon "If It Ain't Broke..." Brown

If you want to adjust distances between chainrings, you can use chainring spacers (from LBS) to move the larger chainring to the left.

If you want to adjust distances between chainrings, you can use chainring spacers (from LBS) to move the larger chainring to the left.Huh? How would adding spacers between the spider-arms and the chainring move it to the left???

Huh? How would adding spacers between the spider-arms and the chainring move it to the left???

He's probably delerious. Seriously, do the Campy trick and mill or scallop out the big chainring at the mounting bolts. Campy did that on all of it's 10 sp cranks to space the chainrings closer. It didn't weaken the chainrings either. Good luck


Tim

Step away from the lathe, mate. Cranks ain't 9 or 10 speed specific. Any attempts to tell you otherwise are pure marketing BS. External bearing cranks work fine on 9 speed and internal bearing (ie; 6500) work fine with 10. The total width of the cassette is the same, thus your chainline will not suffer.

Step away from the lathe, mate. Cranks ain't 9 or 10 speed specific. Any attempts to tell you otherwise are pure marketing BS. External bearing cranks work fine on 9 speed and internal bearing (ie; 6500) work fine with 10. The total width of the cassette is the same, thus your chainline will not suffer.

Half true...

The arms aren't specific, but the chainrings are different widths. That being said, 9 speed cranks will work fine with 10 speed and vice versa...

I recently acquired a 9 speed Ultegra crank real cheap but would like to run 10 out back.

So? Do it. No need to cut anything.


anyone know the width and pitch of the 10 speed teeth?

Ah! Now the confusion becomes clear. There is no difference between the teeth, because the inner bits of the chain are the same between 9- and 10-speed chains. It's the outer width that has changed. The chainring spacing - measured at the teeth - is also the same.

I gather you thought you needed to run 10-speed chainrings on the 9-speed spider. Totally unnecessary. Besides, the rings are different widths (reportedly) so don't interchange.

Don't make this stuff harder than it is.

I've run a 9speed Dura Ace crank on a 10 speed shimano and 10 speed campy set up with no problems.

Im a campy person but i really dont understand why u have to mill the crancks to make them work with a 10 sp set. Get 10 sp chainrings, those are thinner i believe, as somebody said probably even it will work fine as it is. What u should be worry about is about the 10sp cassette not of the cranks, cranks are pretty much standar in distances and as long as the chain fits fine u are ok. I have seen guys running any cranks with campy, even shimano 10 sp cranksets with campy 10. I believe all should work fine dude.

Good luck.

If there is a difference it is probably not enough so that you can notice it in actual use. The manufacturers want to sell new things and need to sow insecurity in the mind of those who have a '9-speed' crank that maybe they need a new '10-speed' crank when they upgrade.