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I've been turning an old bike into a cheap single speed runaround.
Initially I removed the shifters and excess front ring but kept the cassette so I could try out different gear ratios before committing to a single rear sprocket. I also kept the rear derailleur to act as a chain guide/tensioner. Chain and cassette are 9 speed. Like this everything ran fine.
I've now decided on a size for the rear sprocket and have bought a single speed kit including spacers. Now everything is fine until I stand up on the pedals when the chain starts to jump a bit.
The new rear sprocket is 2.35 mm thick which sits snugly in the 9-speed chain. In fact it's much more snug than the geared rear sprockets (and chain rings) which seem to be around 1.85 mm thick.
So how do I get my current set-up to work without the chain jumping? Do I need a narrower (1.85 mm) rear sprocket or is that just for geared sprockets? Do I need to pay more attention to chain line or chain guide/derailleur alignment?
Any advice gratefully received.
Do you have the tensioner pushing the chain down or up? Many of them can be swapped over and I believe that the more teeth the chain runs over the lower the chance of slipping.
Also, you chain may be ****ed.
How taught is your chain? Chainline is very important if your running a 9spd chain so give it another check.
Chain is most probably scrap...or reuse on an old 9-sp setup on another bike.
Aim for the best chainline you can get, but +/- a few mm is usually OK.
Get a new rustbuster KMC single-speed from CRC for approx £9.
These were on offer at £4 a few days ago!
http://www.chainreactioncycles.com/Models.aspx?ModelID=25653
PaulD
Thanks for the replies.
"Tensioner" is the old derailleur so top jockey wheel pushes chain around sprocket as far as possible - don't think that's the problem.
Also chain is new so not that either.
Sounds like I need to look again at chanline. I admit I was a bit slack setting it up as I assumed the derailleur would cope with it being off like it does in a geared system.
Talking about chain tension, I could take some links out of the chain, although this wan't a problem with the cassette on similar sized sprockets. What angle of tensioner/derailleur should I aim for, 45 degrees forward?