Single speed free wheel question .

Todays question please.
Vintage single speed screw on free wheels, do they only fit a hub built for a screw on free wheel,or can you get one that will fit a fixed gear hub.
As I under stand it,a double side fixed hub will only take single fixed sprockets either side,and not a single speed free wheel.
The thread on a fixed hub has two,one for the sprocket and one for the lock ring on.

Your input please.

The single speed freewheel will screw on the inner thread of a fixed wheel but will overhang some empty space above the narrower left hand thread

Usually, one side has a fixed type stepped threading, and the other side is threaded for a standard freewheel. Occasionally you may find double sided fixed hubs with stepped threading on both sides, but these are rare and only a few companies offer them. The fixed side has a stepped down diameter thread to accept a lockring. The larger diameter thread on the fixed side accepts a standard threaded cog, and uses the same size threads as the freewheel side of the hub. The most common standard I.S.O. thread size is 1.375" x 24 tpi (threads per inch), but there are other less common older sizes (British 1.370" x 24 tpi, French 34.7 x 1 mm, Italian 35 mm x 24 tpi).

Re:

Thank you gents .The 3 rear hubs in question are all double sided fixed. Two are BH airlite large flange, not sure what the other is as an unmarked steel small flange .
TDC freewheel should fit then?

Hold the press... :facepalm: just been and had another look .
The two built into wheels are both double fixed, and the loose hub is fixed one side are freewheel the other .

A few projects on the go at the moment and I am trying different ideas for the builds. stuff all over the garage :roll:
1/ An early FW Evans. nearly finished.
2/Saxon tt. a bit still to do.
Pinched the wheels out of a Carlton for the Saxon and replaced the rear with a double sided fixed. Carton changing from a 10 speed to a single speed f/w with a 38 t TA chain ring on a Williams AB77 c/s.
Donor set
Williams AB 77 by rebalrid, on Flickr
The Williams C1200 is a bit big for Derbyshire .
Williams Chainset by rebalrid, on Flickr
All good fun .
Next year I will change it all back :?: :shock:

Re:

I'm no engineer and will happily stand corrected, but intuition kinda tells me not to thread a freewheel onto the half-width stepped thread. Is there not a chance of messing up the alloy thread on the hub with the constant load changes that cycling brings?

Re:

Been fishing...
https://www.cyclechat.net/threads/freew ... ub.138497/

https://singlespeedcomponents.co.uk/pag ... ity-issues

https://www.lfgss.com/conversations/160372/

http://www.bikeforums.net/singlespeed-f ... k-hub.html

Now to sort out the wheat from the chaff.

It's fine to use a single-speed freewheel on the fixed threads.

Think about how much overhangs on a 6- or 7-speed screw-on block. The single-speed gear is in the same place as a fixed cog and the thread contact is the same.

I don't want to labour the discussion, esp as I'm not sure who is correct, but ...

Think about how much overhangs on a 6- or 7-speed screw-on block.

Click to expand...

but with a block, a vertical plane inside the block rests against the end (shoulder) of the thread, so it is secure in terms of twisting forces.

The single-speed gear is in the same place as a fixed cog and the thread contact is the same.

Click to expand...

not quite, as a single freewheel is wider ... hence it overhangs and the chain line will be in the centre of the freewheel, roughly a point above the end of the thread, not the centre of the thread.

explanation may be messy, difficult to word without diagrams

Fixed cog also "overhangs" the threads, it needs to so that the locking can lock it into place without fouling the threads that hold the cog on. The freewheel as you say will overhang more but in practice it seems to make no difference and works (it did in the 1970's ).

the single speed FW still butts up to a shoulder.