Bicycle Mechanics - Fixed gear: chainline off... spacer?

My chainline is off, and it's making noise and going to wear my chain, cog, and chainring more quickly.

I need to move my cog farther outward (toward the seat stay). Are there spacers that will do this? Can I just screw in another lockring?

You shouldn't have to correct your chainline at the back if you're using a legit track hub.
If the chainline is off, you need to correct it at the front by installing a different length bottom bracket spindle.
If the rear hub has a 120mm over-locknut dimension, the distance from the center of the seattube to the center of the chainring should be around 42mm.

I am giong to guess the OP does not have a track hub on there. Just a hunch. I will also guess that we are talking about a threaded freewheel hub with a track cog screwed on. You likely would be able to fit a BB lockring behind the cog and still have enough threads showing on the hub for the cog. But I am not sure I would advise it. You really want that cog to shoulder up against the hub itself. I would be afraid of stripping the hub if the BB ring had any play at all in there.

Can you switch the chainring to the inner position on the spider? Can you put a small spacer between ring and spider to bring it farther in-board? Can you switch around the BB spindle (if cup and cone), many older spindles are assymetrical and you can bring it in quite a bit that way.

If no to these, you either have to get a shorter BB spindle or else respace and redish the rear wheel.

jim

If the rear hub has a 120mm over-locknut dimension, the distance from the center of the seattube to the center of the chainring should be around 42mm.


Yes. But, then this is true of a track hub regardless of what rear spacing it is for. The two numbers have nothing to do with each other.

jim

Yes. But, then this is true of a track hub regardless of what rear spacing it is for. The two numbers have nothing to do with each other.

jim

There are older track hubs out there that have a 110mm OLD. With those, the c/c should be more like 40.5mm.

And I'm hoping the OP has a proper track hub because a modified freewheel hub is just an accident waiting to happen.

Yes. But, then this is true of a track hub regardless of what rear spacing it is for. The two numbers have nothing to do with each other.Well, the seattube to chainring distance should match the centre of the hub to the cog. If the hub is set up correctly with the cog 42-45mm from centre, then the front chainring needs to match that spacing as well.

There are older track hubs out there that have a 110mm OLD. With those, the c/c should be more like 40.5mm.

And I'm hoping the OP has a proper track hub because a modified freewheel hub is just an accident waiting to happen.

I don't know what chainline standards would apply to a 110mm hub. If that has ever been out there, it is well before my time. As far as I know 42mm has been the only track standard for at least 30 years. I am not saying you are wrong, I just don't know anything about that. I highly doubt that the OP has a hub like that in any case.

I respectfully disagree that a respaced/redished freewheel hub is not a practical solution to this. The only, and I mean only, disadvantage to them is that they should not be relied upon as a sole braking mechanism. Its pretty hard to spin off a cog that has been fully tightened on, but it is possible. So, expecting one to stop you in a skid stop is probably not a good idea. But if one is running a front brake, then there is no reason to avoid a suicide hub. Horrible name notwithstanding.

jim

Well, the seattube to chainring distance should match the centre of the hub to the cog. If the hub is set up correctly with the cog 42-45mm from centre, then the front chainring needs to match that spacing as well.


Absolutely. But the distance from the center line has nothing to do with what further distance there is to the inside of the dropouts. For example, the chainline of the rear hub is what it is, regardless of whether or not the drops have been spread or squeezed together.

jim