DemonHunter

Hello guys,

This is my first post on this forum and I am looking for some advice on how to fix my problem. Thanks in advance!

The gear I have:

• Sturmey Archer HBT30 flip-flop rear hub with 130 mm OLD -> spec link -> sturmey-archer.com/en/products/detail/hbt30-r-silver
• Sturmey Archer SFS30 freewheel cog -> spec link -> sturmey-archer.com/en/products/detail/sfs30-18
• no name fixed cog with a Sturmey Archer lock ring

The problem:

I measured both chainlines (freewheel and fixie) and I got a difference of 3 mm between them. My expectation is to have a unique chainline so I can flip the wheel without doing anything else. Am I wrong? This is the first time I am building a fixie bike.

• freewheel cog chainline seems to be 45.5 mm (130 / 2 - 19.5)
• fixie cog chainline seems to be 42.5 mm (130 / 2 - 22.5)

Photos -> imgur.com/a/cOZXS6l

TejanoTrackie 

You could probably move an axle spacer from one side of the hub to the other and redish the wheel to get a more equal chainline. What is the chainline of the chainring ? That should be your target for the cog/freewheel chainline.

DemonHunter

Hi.

I don't have a crankset yet. I plan to buy one after I solve the freewheel chainline. To be honest, I don't want to move the axle and redish the wheel. I was expecting that evything will work out of the box with a standard chainline (42.5 mm).

After more looking, I think the freewheel cog is not compatible with the flip-flop hub (even if they both are made by Sturmey Archer).

If you look closer, there is a gap of 2-3 mm between the hub and the cog. Sadly, the cog has a smal flange inside (after the thread) that will not let it to go closer to the hub flange (I uploaded a new photo here imgur.com/a/cOZXS6l ). I am very disappointed on Sturmey Archer.

I am looking for a new freewheel cog without any flange. Any recommendation?

Thanks

TejanoTrackie 

Just about any standard freewheel should work. A good affordable choice is the ACS Paws >>> https://www.retro-gression.com/colle...paws-freewheel

Mikefule

For comparison, if you were riding a derailleur bike, you would have considerably more difference between any two adjacent ratios, never mind between highest and lowest, and you would just accept that that is how bikes work.

I doubt you will even notice 3 mm in real world use. However, if you set it up so that the perfect theoretical chain line is exactly between the two, then you will never be more than 1.5 mm out.

I think this is the sort of variation that you would not even know about if you had not measured it.

DemonHunter

Well .. I guess, it depends. The derailleur bike is using a special chain. The chain used for single speed bikes will not work with this difference.