Calculating SS set up

mattsccm

Senior Retro Guru
Decided not to clip this on to the SS/Fixed thread that's going as I'll end up with an answer to fry my brain.
Is there a method/crib sheet that would allow me to work out what sprockets I need to SS a bike without trial and error? too lazy to keep swapping stuff and to tight to buy just to find out it's wrong.

I guess this would involve the chain stay length plus teeth on freewheel and chain set. I cannot visualise maths in my head so need pretty pictures or charts to look at and colour in.

Why? Bike I want to convert has vertical dropouts and fiddly alloy inserts for mech hangers so no filing.
 
Re:

I'm not sure there is a formula.... or at least not an easy one for the layman.

Just a case of a magic gear (ie luck) given vertical dropouts, unless you have an eccentric bottom bracket.

A half link chain might help with fine tuning
 
Are you trying to get a magic gear?
See here: http://www.63xc.com/toddp/halflink.htm

But beware, as the chain wears you will need a tensioner or else the flappy chian risks un-shipping, which isn't terrific fun.
I've been riding singlespeed off road for 10 years and all this magic gear stuff always seemed too fiddly. In the end I swapped to a frame with horizontal dropouts and eliminated the tensioner.
 
Re:

The whole point of the 'magic gear' is to avoid fitting the ugly chain tensioner. OK if you are prepared to fit a new chain every month.


Vertical dropouts really are a way of saying: "F@*k you, single speeders!"
 
Re:

Ages ago I saw and used a formula based on chainstay length which put you in the ball park if your preferred gear would probably work or not.

Practically though, measuring the
chainstay accurately is one thing, then buying stuff is still hit and miss due to manufacturing tolerances and varitions of wear if you will use
an old chain / chainring / sprocket.

Having a chsinstay a fraction too long is the best because you can file a flat (2mm at the very most)on the rear wheel axle to allow a
new chain to initially bed in.
 

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