Fixed both sides on a flip flop hub


Bexley, Kent
I have a flip flop hub. Usual set up - fixed one side, freewheel the other. Is the free wheel fitting normally the same as the fixed fitting? In other words, can I remove the freewheel and replace it with a fixed sprocket? I have 18T fixed at the moment and was thinking about adding a 19T on the other side for those occasions when I might need a little help on the hills. Would I have chain length issues if I did this (bike has horizontal drop outs).


Legendary Member
No real issues. You won't have a proper left hand threaded locknut but it is usually okay without as myself and many others who use normal threaded hubs meant for freewheel blocks will confirm. A little Thread Lock if in doubt.

EDIT: If there are enough threads, a lockring meant for a standard 1 3/8" x 24tpi cup and cone bottom bracket will work as a lockring.

Each additional tooth on the sprocket/chain wheel will move the axle forward by 1/8" (IIRC) so you should be okay with a single tooth difference. You will know how much adjustment you have at the moment. I wouldn't like it too close to the front of the drop outs in case it slips forward and out.


Man or Moose!
I think, most flip flop hubs have one size machined for a lockring, the other side doesn't. The net result is that you can run a freewheel on either side, but can only run the fixed cog on the side with the lockring thread (steering clear of riding fixed without a lockring debates).

Note I said I THINK, so don't take my word as final :smile:


Here for rides.
these hills, is one tooth going to make a difference, really?

me: I prefer the bail out flip my legs are very tired option of a freewheel once I get past 100km. That said I've only done it twice I think, and both times it was for the downhills and a spot of coasting thereafter.


Europe Endless
My one is fine with a 2 tooth difference.
Not sure I've got long enough dropouts for more than that.
39 to 15 fixed or 17 freewheel, on a 700c :biggrin:
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