Trouble correcting my disobedient chain

So I am in the middle of converting my 80's Peugeot frame into a fixed and sent it to a reputable bike shop to replace the chain, put on new wheels, tires ect. ...(easy enough to do yourself but for a fiver it saved me the trouble)...

For the first couple of weeks it was fine but now the chain is slightly too slack to stay on ... say when I get some speed or whilst pedalling off a curb. I had only gotten around 50 miles out of it and the chain is good quality.

I took it to a bike shop - This time I went to halfords. I also asked the guy to put some air in my tyres and he couldn't figure out what the valve extender was so I already had my doubts about him. Anyway he said the only way he could see of fixing the problem is a new crank set. Apparently there isn't enough slack in the chain to take any out of it and the wheel won't go back any further and the dropouts are not horizontal.

Can anyone suggest alternatives?

what drop outs do you have?

"Trouble correcting my disobedient chain!"

Sorry, with that title I thought this was an s&m thread.

Can anyone suggest alternatives?

Eccentric rear hub: http://whiteind.com/rearhubs/singlespeedhubs.html

Fixed with vertical drop-outs requires either a 'magic gear' (google it) luck and religious devotion to chain cleaning and lubrication, or some other means of adjusting the distance between the centre of the cranks and the centre of the wheel: an eccentric hub or eccentric bottom bracket.

Sheldon had a neat bodge with cutting down a quick-release axle so that only the sewer projects into the dropout, buying a little more adjustment range.

A half link might get you close enough.

To get your magic gear to fit, changing the sprocket would probably be cheaper than changing the chainring (especially if it's part of your cranks).

A ghost cog/ring/sprocket could take up the slack to stop the chain coming off, but will still leave you with all the backlash - as you switch between accelerating and braking it moves up and down, letting the slack move between the top and bottom run of the chain.

You could find someone to replace your drop-outs with track ends. That would ultimately be the best solution as then you wouldn't be restricted to special components. (Unless yours is a high-end classic Peugeot, so that butchering it would make you a puppy-killer.)

Fixed with vertical drop-outs requires either a 'magic gear' (google it) luck and religious devotion to chain cleaning and lubrication, or some other means of adjusting the distance between the centre of the cranks and the centre of the wheel: an eccentric hub or eccentric bottom bracket.

Sheldon had a neat bodge with cutting down a quick-release axle so that only the sewer projects into the dropout, buying a little more adjustment range.

A half link might get you close enough.

To get your magic gear to fit, changing the sprocket would probably be cheaper than changing the chainring (especially if it's part of your cranks).

A ghost cog/ring/sprocket could take up the slack to stop the chain coming off, but will still leave you with all the backlash - as you switch between accelerating and braking it moves up and down, letting the slack move between the top and bottom run of the chain.

You could find someone to replace your drop-outs with track ends. That would ultimately be the best solution as then you wouldn't be restricted to special components. (Unless yours is a high-end classic Peugeot, so that butchering it would make you a puppy-killer.)

http://www.flickr.com/photos/timwilson/179159561/

The Puppies are safe.. it isn't a high end Peugeot, the image above is pulled from the net but same model. I think originally the first bike shop said he had put a half link in so would I not be able to remove that? I don't know how that works...

The magic gear sounds pretty useful I might give it a go...

I was just hoping for a cheap(er) reliable commuter for uni to last me for a few months until I get something worth showing!

That looks like it has semi horizontal dropouts?

There is probably enough space that you could file/grind some material from the back of the dropouts(?). Even if you removed the entire back (raised, rounded) portion -- about 3/16" -- on which the skewer clamps, there would still be plenty of flat space left in the dropout at the top and bottom of the axle for sufficient clamping pressure for retention, AND the un-raised bit, along with the chainstays and the seatstays, should be contiguous and strong enough to keep the back portion of the rear triangle soundly together. This removal of material should allow enough horiizontal space for you to take up the slack. :-D

...and, if there are threaded adjusters at the backs of the dropouts, you could always just remove them. That would buy you an eighth inch or so.

 But if the dropouts are stamped, instead of forged, (as with the Peugeot UO-8) -- removing any material per my earlier suggestion could be ill-advised.  Depends on how much metal you could leave while still producing the desired effect.   :-/