Self build singlespeed.

redddraggon

I've decided to start cheaply acquiring parts to build a singlespeed road bike. I've already got the wheels, just need to find the rest.

I don't want to use a chain tensioner, and my plan is to use a Sprocket and a 39ring off a double chainset, with a frame with vertical dropouts. How accurate do you need to be with chainlength to keep the chain from coming off?

I'm planning on using wheels which have the normal 8 speed freehub on, how can I can keep the sprocket secure?

As I want this bike for the need of minimum maintainance, I'm looking for a cheap (<£50) Al frame, any body have ideas (bar ebay) of where to get one, easily accessible from the North West?

(I don't want to go fixed due to hills and my love of freewheeling)

Please excuse my spelling mistakes, I don't seem to have installed my spell checker on this computer

Monty Dog

You may want to post this is special interests too..but:
You'll need a spacer kit to use with your sprocket to make sure you get the chainline right. If not using a tensioner then you're looking for a 'magic gear' combination with your vertical dropout - which probably means trying different chainring / sprocket combinations to get it bang on with your chainlength. Consider using a half-link chain as it give more chainlength adjustments - but these are only 1/8" - and run quieter with a 1/8" sprocket. The only problem is that chains do stretch and you have no means of adjusting out tension.

PHcp

There's a good guide to finding magic gears here;
http://www.63xc.com/toddp/halflink.htm

Consider using a half-link chain as it give more chainlength adjustments - but these are only 1/8" - and run quieter with a 1/8" sprocket.

3/32" half links are available, though harder to find, I've had them from SJS and charliethebikemonger on Ebay who's also a good source for spacer kits. I run a hub gear with a half link and a SS chainring which has higher teeth. Unlike with fixed, with SS you don't need to be that particular about chain tension (look at old photos of bikes with SA 3spds) removing half a link at a time is close enough.
Another option is an ENO eccentric hub, at £120 it'd blow the budget, but it'd convert any bike to fixed/SS without worrying about chain tension.

EDIT - Charlie the bikemongers website, I remembered that's where I got the SS chainring.
http://www.charliethebikemonger.com/index.htm