Magic Ratio for Single Speed. Any Experiences?

[Thame Game]

I'm just converting an old Peugeot hybrid to single speed. It has vertical drop outs, so it's either a chain tensioner or the Magic Ratio.

Sounding like a 1970's Miss World contestant, my measurements are:

Front ring 43t (non optional)
Chainstay 45.5 cm
700c x 35c tyres

The calculator is giving me a rear cog as 17t, which sounds good to me because Gusset do a wide width version that prevents my cassette body getting chewed up.

Should I commit?

 

[Rod_Saetan]

Where are you riding the bike? Doesn’t sound like an easy enough off road ratio to me, I used to aim for 2:1 + 2 chainring to sprocket, ie: 38:18. You may of course be able to push a harder gear than my pathetic body could manage.

 

[Thame Game]

Where are you riding the bike? Doesn’t sound like an easy enough off road ratio to me, I used to aim for 2:1 + 2 chainring to sprocket, ie: 38:18. You may of course be able to push a harder gear than my pathetic body could manage.

Mostly a townie with gnarly tyres for cross tracks.

 

[grantoury]

Sounds like a good ratio, will give plenty of speed but still manageable on hard surfaces.

 

[benjabbi]

Tends to work fine until the chain wears a bit, then you'll need a tensioner anyway.

 

[MattiThundrrr]

I used to aim for 2:1 + 2 chainring to sprocket, ie: 38:18.

I learned that formula as well, heard it from the BMX forum for building their 26" cruisers. It is an easy ratio to cruise with. In my case, 32:15 was ordered, but a 13 tooth rear was sent. I decided to try it out, have been living with it for a couple of years. It is interesting, I do have to walk up some hills, and the pace is a little rapid sometimes, but it has pushed me to be better for both reasons. Gotta be stronger to push it up the hills, and gotta be better to ride the trail at a livlier pace.

 

[grantoury]

Tends to work fine until the chain wears a bit, then you'll need a tensioner anyway.

I would always go for a tensioner, it leaves much more choices, which is kind of important if you only have one gear.

 

[Thame Game]

I would always go for a tensioner, it leaves much more choices, which is kind of important if you only have one gear.

I may go for a tensioner in the future, but for this build it would spoil the aesthetic.

 

[Gtpulse]

I fitted a half link to the chain when running fixed on vertical dropouts to get the right tension.