Is it a setup issue, bad technique or inevitable that occasionally I throw the chain on my SS?
Previously I've thrown a 9spd chain off a trackend tensioned SS.
I then moved to a 1/8" chain and it still happened, but less often.
Last night I threw a 9spd chain, surly singleator tensioned, off. Id have thought a tensioned chain - even a 9spd - would be less likely to come off.
Im a big lad, and quite strong on the SS at the moment. But I probably flop the bike over a little bit when honking - is that what's causing the the chain to derail: twist/flex of the rear triangle plane?
This isnt a "clattering" derail on a bumpy descent either, its just a short sharp, steep honking climb.
On a similar thought, climbing a greasy 16% road climb, SS, with chunky Stouts on the back, I get a bit of tyre slippage. Especially if Im "dancing" on the pedals a la albert (it kind of un-weights the rear wheel a little bit on the start of the upstroke of the crank rev). Do road rider (especially featherweight ones) have traction problems on really steep climbs and naff-all rubber?
some chains are worse than others. pc-1s have got floppy. and they are next to useless now.
im using a chunky ugly KMC 1 spd chain at the moment on the tensioned bike.
[i]Do road rider (especially featherweight ones) have traction problems on really steep climbs and naff-all rubber? [/i]
Doesn't have to be particularly steep if a bit wet and greasy and you have too much weight over the front wheel. (I'm no featherweight btw)
When I ran my old steel Kona as a SS with a reasonably wide rear tyre, I got enough flex to make the tyre rub against the chainstay. this was when I'd not been riding SS for long so wasn't as strong and I'm, erm, probably a little lighter than you.
I can see how you could flex the rear enough to unship a chain. (I assume this is on the chainring, rather than sprocket?) A front mech doesn't have to move the chain far to start a shift, after all.
i have a trek 69er ss, used to drop the chain at the back quite painfully from (i'm pretty sure now) frame flex - i put a couple big cogs from an old cassette spaced either side of the main one, it's never come off since. bit of a weird solution but did notice that they originally came with something to keep it on.. [img] 
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i also sometimes have the back end coming off the road when sprinting up hills on a road bike incidentally, just too far over the front - i don't know if the two are related though!
Never had that problem, i use single speed specific frame and surly chain rings front and back, not sure if that makes a different due to taller unramped teeth.
Does not seem to happen to track riders and they produce pretty high torque so i guess it could be something to do with your set up.
Could always try Charlie the bike monger and see if he has any ideas.
Losing a chain is poor setup, lifting the wheel is poor technique.
in my case the chainline was perfect, chain tight, decent ss specific and straight cog/chainring.. i imagine the other guy is the same - what else is there?Losing a chain is poor setup, [yeah i agree with this bit]
You should try running it on a belt-drive. Bl00dy belt comes right off.
Solution:
More tension.
Bolt-thru hub to stiffen the rear end.
And probably check your chainline is perfect.
Got the same with a scandal but I think it's down to the frame getting a bit nasty from years of ss abuse.
I had to walk up a stream & algae covered bit of road last night on the SS as I couldn't find traction at all. Every pedal stroke just slipped the back out - 'twas too steep to sit and spin out on, which is how I'd (probably) have gone at it on a geared bike, but grinding my way up it just slipped the back out continually.
I use Surly cogs at both ends, and have not had any chain problems - those cogs have good long teeth and hold the chain in well. I don't have [i]too[/i] much tension - not enough to slip off, but not too tight either.
I did find my Pompino was way too flexible around the BB, so it went on it's way pretty quickly - but I could see how that would have started throwing it's chain / rubbing it's tyres/stays and the like if I'd have carried on with it.
I do find that I'm stretching chains a lot tho' ...
I have groove armada sprockets and a Thorn SS front ring. Loads of tooth and a beefy chain.
However this is happening on my Scandal as for you tazzy. Its not built like a landrover chassis out the back, that's for sure.
Oddly I find my pomp is much stiffer, have never dropped a chain on it (PC1 always) and have honked that up some pyreneean climbs.
Does the Singulator push up or down. Using a push up one can lessen the chances of this IMO. I have even seen the singulator zip tied or bungied (many loops) towards the chain stay to increase the tension when pushing up.
My pomp is a flexy thing, but, its also majorly let down by a crap freewheel, crap chain, and cheap mountain bike ring on front.
Eventually i'll lavish a bit of cash on it.
But, right now i'm playing a game of how cheap can i keep it running.
currently down, but it has the derailing is on the front ring Im sure. When honking with the bike flopped, in my minds eye I envisage that the chainwheel and sprocket planes become oblique to each other. With the effect that the chain as it approaches the top of the chainwheel is no longer approaching at exactly dead on
My dad agrees with angryratio, chain device pushing up, he thinks you need more wrap?
Flex is possible. Something like the guides in the pic would be good. Where can you get them?
Try it pushing up. Had the same problem on my Kona pub (tm). Also fiddled with the front/rear ring sizes and put a half link in to have as little slack as possible and it cured it.
Tensioners IME are crap - track ends etc way better.
I can't say what's causing your problem but I know 1/8 and an old rear mech helped before I hot sliding drop outs.
TroutWrestler - Member
Flex is possible. Something like the guides in the pic would be good. Where can you get them?
i couldn't find anywhere.. so ahem
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please excuse greenery, also that pedal is another bike