what sized chain ring and sprocket?

[biggs682]

Just finished building a single speed using parts from the spares box so ended up with a knee popping 39 x 15 set up , much prefer something like 52 x 18 and a lower cadance

 

[Pennine-Paul]

Just finished building a single speed using parts from the spares box so ended up with a knee popping 39 x 15

Err 39x15 is only 68"! Do you mean 49x15??
I used to run 84" (48x15) on flat routes without any problems,one of my colleagues used to run 52x12! that is knee popping gearing!

 

[Smurfy]

Just finished building a single speed using parts from the spares box so ended up with a knee popping 39 x 15 set up , much prefer something like 52 x 18 and a lower cadance

39x15 = 18.6mph @ 90rpm on 700x25 tyres
52x18 = 18.6mph @ 81rpm on 700x25 tyres

39x15 = 14.5mph @ 70rpm on 700x25 tyres
52x18 = 14.5mph @ 63rpm on 700x25 tyres

 

[biggs682]

Err 39x15 is only 68"! Do you mean 49x15??
I used to run 84" (48x15) on flat routes without any problems,one of my colleagues used to run 52x12! that is knee popping gearing!

no 39 X 15 is correct

39x15 = 18.6mph @ 90rpm on 700x25 tyres
52x18 = 18.6mph @ 81rpm on 700x25 tyres

39x15 = 14.5mph @ 70rpm on 700x25 tyres
52x18 = 14.5mph @ 63rpm on 700x25 tyres

using spares from spares box and knee popping due to amount of spinning

 

[bonsaibilly]

Can't you count the teeth on each cog? BB