Bottom cog on rear off center

[jrp76]

I took the cogs off my back derailleur to clean them. When I went to put them back on I noticed that while the top cog was centered and it didn't matter how I put it on, the bottom one has the teeth off center to one side or the other. Does the side with the teeth go towards the center of the bike or the side away from the bike?

[RobAR]

Hi jrp! What make/model of rear drlr do you have?
If I am reading it correctly, I think that you actually meant that you removed the 'pulleys' rather than cogs. A little tech thing that makes us old guys think too hard sometimes.
The pulleys on many drlrs are specific to being a 'guide' or a 'jockey', Upper and Lower. 9 times out of 10, the upper will have a small amount of side-to-side play while the lower is fixed.
We really need a bit more info...

[jrp76]

Thanks for the response.

It is a SRAM X-7 drlr. Yes, I did mean pulley sorry The upper pulley is symmetrical so it doesn't matter which way it goes on, but the bottom one has the teeth offset to one side, so it probably does matter how I put it on.

[RobAR]

Okay... I have in front of me an X0 and a X5. Both are 2010, I think. Neither have a pully that has the teeth off-center and nothing on the SRAM site shows that detail.

The pulley should only consist of the wheel itself, a metal bushing through the center of it and two aluminum dust covers, one on each side. Supposing that you have it assembled correctly, my guess would be that the teeth go outboard (away from wheel). It's easy enough to put it in and then flip it over if you get chain-rub on the cage.
Can you post a pic? You have my curiosity up...

[jrp76]

[attachment=1849]

Sure, here it is. You can see the teeth are on the right side closest to the bike.

[RobAR]

I think I totally missed what you were saying. Yes, your pulley is made that way but, when assembled, the teeth should be centered in the cage. I was trying to imagine why the teeth would be offset from the centerline.

[jrp76]

Ah, sorry for the confusion. The teeth are "centered" so to speak, but the pulley on the bottom is formed a little different where one side of it is raised (the left side looking at this pic) and the other side is flat (the right side). Does it then matter which way it is put on? Why is this pulley shaped different than the top one where both sides are raised on it?

Thanks for all your input.

[RobAR]

I took a look at an X-5 today and it's the same. I can only guess that SRAM made it that way so that it's easily distinguished from the upper pully.
The conical side goes toward the bike, the recessed side outwards.