I finally took the plunge and converted my 24-speed CX bike to a single-speed last night. Thumbshifters, front der, cassette, big ring, granny - gone. I kept the rear der to use as a chain tensioner/aligner, although I'm only using the upper pulley and can grind off the lower cage. I wimped out and got Spot's spacer kit and pirated the 14T off my old XT cassette. I used the existing chain, 'cause the new one I bought kept skipping. The new stem is an engraved Pinarello by 3TTT that I found in my basement. Questions:

1. How good does my chainline have to be?
2. I can't get the chainring bolts to hold the chainring tightly onto the crank. There's just a hint of play. Should I use a couple of thin washers?
3. How uncool is it to use a chopped rear der as a chain tensioner? It's Suntour from the 80's...

The new stem dropped my straight bar about 3" from its old position, so I am much more aerodynamic and teh f4st4r! I rode it today, and it feels lighter and less sketchy than before. I'll post some pictures soon.

get the right chainring bolts!

^^^^^
It would be swell if you could elaborate. How long are the bolts? I don't have a track ring or anything, it's just the old Sugino 38T / 110 BCD.

You should be able to get BMX bolts at your local shop. I've used them before.
I've also used spacers but they felt a little sketchy.

You need these----->https://www.webcyclery.com/home.php?cat=302

Groovy! Thanks for the help. Any comments on questions 1 and 3?

1. It should be as dead on as possible. If it's off too much, it could skip off too easily.
You shouldn't have too much of a problem with the spacers.
3. Using something you already have instead of a $50 singulator = tittts.

check out this site to see if you can get away without using a tensioner at all

https://www.peak.org/~fixin/personal/fmu/php/formfmu.php

if you can find a good gear ratio that will work you won't have to use your derailleur

Your spot spacers should allow you to put the cog where ever the chainline is best. I you have the option go for the best chainline possible.

As for the tensioner an old der works well enough but the singulator is a faily graceful solution. If you are using one for road use I would recomend pushing the chain up insted of down. This gives you more contact with the cog.

I was thinking about a Singleator, but the existing der is free, so...
I might try to run without a tensioner as well, but I'll need to get a slip link or whatever those things are called. That website is pretty good, lbthomps. Thanks!
The chainline is not bad right now IMHO, but I'll try and tweak it a bit more. Thanks people! I'll post pictures tonight in the photo thread. Ciao!

Buy a proper SS cog. The pirated cog from a cassette will be likely to derail at the worst possible time, like when your hammering up a muddy hill.

They're like $5.

Like this:

https://www.webcyclery.com/product.ph...cat=402&page=1

More:

https://www.webcyclery.com/home.php?cat=402


DON'T get alloy chainring bolts.

is the cyclocross bike you used the '87 bianchi axis you have listed in your signature? does it have vertical or semi-horizontal drops? i would think a bike that old would have semi-horizontal drops, thus you wouldn't have to run a chain tensioner or rear derailleur at all if that is the case...

i second the bmx cassette cog as well.

OK, looks like the price of my conversion is spiralling up to the $50 mark. I love buying bike s#!+.