I’m setting up my old Pace 405 frame to run singlespeed, and just can’t get the chain to run smoothly.
I’ve got a Yess ETR/D chain tensioner ( http://labs.yesspro.com/products/etr-d) fitted, and a single Surly cog, with a variety of Surly spacers. Whatever combination of cog positioning I try, the chain clunks irregularly when I pedal (just along level road). I’ve tried setting the spaces from one extreme to the other (from the chain falling off inside the cog, to the chain falling off outside), and just about every combination in between, but whatever I do it “clunks”.
anyone got any ideas?

I would guess it’s the chain slipping round rather than sideways

Is it a new chain & sprocket?

It could also be a stiff link going through the tensioner

yep new chain, sprocket and chainring. I wondered about a stiff link, but it seems to be very irregular. I’ll check the whole chain again. maybe take a couple of links out? (sadly Yess don’t provide any setup guide)

Not enough tension in the chain probably.

Is your bottom bracket OK ?

Chain clunk , I would check chain tension first , needs to be fairly tight, then chain , sprocket wear ( assuming chain line is ok).

Have you got the chain tensioner on right, I remember when I did my sons’, it wasn’t obvious which way around the chain ran.

Is the chain wide enough for the sprockets, my chain took some time to settle in when I first built my SS. The chain hung up a little on the teeth on the sprockets.

You might slate me for stating the obvious. But have you tried looking down at the drive train while puting pressure on so you can give us all a clue about might be actualy happening?

You might find you get a few more helpfull posts/ a few less mistic meg posts. 🙂

Is the joining link in te chain wider than the rest of them? Clunking as it goes through whatever bit its hitting off at the time – determined by where the chain is sitting on the cogs at that particular moment in the space time continuum. Either that or its a gammy flux capacitor ken.

Yes i have but i can’t see what’s happening….with the bike upsidedown it barely clunks (more clicks!). With me on it….I can’t see what’s going on!
Chain tension seems like a good place to start maybe?

Is it just a noise or can you feel it through the pedals?

I ended up going for a SS specific FS frame in the end though my Trance worked pretty well

The link for the tensioner doesn’t appear to work for me but, if it’s a FS bike is the chain tension not constatly changing as the suspension compresses, or does the frame have a pivot around the bottom bracket?

you can feel it through the pedals, definitely.
Hicksy, the tensioner is made specifically made for FS frames, and looks, and works, like a rear mech., so it takes up the slack as the chain grows.
I’ll have a play today and take a couple of links out of the chain, and maybe see if I can put more tension in the tensioner (the spring position is adjustable)
thanks for the ideas so far!

What tensioner are you using?

The only one i’ve seen that works consistantly well on a full suss is the Rohloff one.

Twodogs – I’ve got a Yess ETR/D chain tensioner http://labs.yesspro.com/products/etr-d fitted

singlespeedstu – What tensioner are you using?

the basic superstar components worked fine for me

I still say the only tensioner i’ve seen work consistantly well on a full susser is the Rohloff.
Though I recon a sort cage shadow + mech would work even better.

I take it that the cog, chainring, & chain are all compatible (and if 1/8″ the tensioner is suitable)?

Lots of people were using rear mechs at sswc but they look rubbish

The yess one should be fine, I doubt that’s the problem

the Yess tensioner gets some good write-ups around the web.

Psling, I’m starting to conclude that the chain isn’t compatible with the cog…I’ve spend some time today fiddling, and putting more tension in, but I’m still getting the “clunk”. I’m starting to wonder if the chain is not sitting on the cog properly, and then slips onto it under pressure – which would explain why it doesn’t clunk with no pressure.

not sure what chain I’m using, other than I knowa KMC (?).

Is the cog a 1/8″ (BMX) cog whilst everything else (including the chain – 9speed maybe) is 3/32″?

ok…just checked:
Middleburn Mono 3/32″ chainring
KMC 3/32″ singlespeed chain
Surly splined singlespeed cog..3/32″

so that should all be fine. I guess the only thing I don’t know about is the pulley wheel on the tensioner…I think I read somewhere that it’s a “Shimano standard”..whatever that is. maybe that’s not OK with a 3/32″ chain

What rear hub is it?

The shimano jockey will likely be 3/32 too so all compatible.
What size cog is it? If smaller than 16T (say for DH use) you may not be getting good chain wrap causing a slip.
Or maybe the freehub needs servicing… Maybe where davidtaylforth’s ‘chain’ of thought is going…? 😉

It’s a Hope Pro2, with spacers to put the cog in line

Strip freehub, give it a clean and put some fresh grease in there.

Edit

Maybe where davidtaylforth’s ‘chain’ of thought is going

Great stuff!

it’s a 16T cog. I’d not thought about the freehub being knackered…it has been sitting round unused for a while. I could also quite quickly swap wheels for one that I know has a sound hub.
thanks guys…I’ll let you know how I get on

OK. I give up. I tried another wheel…exactly the same result. I wish I could see what’s actually going on, but it doesn’t happen with the bike in the stand.
I really have no idea what to do next 😐

The only way ive ever got a silent drive on a SS is by using 1/2 x 1/8 chain regardless of chainring and sprocket width and pitch.

it’s not the noise that I’m worried about…it’s the slipping (if that’s what it is)

Get a friend to ride it down the street while you watch.

I found my trance worked perfect with a 18 tooth but slipped with a 20 and a 17 tooth. Round here I ran it with an 18 but at SSWC I ran it with 20 and a slightly too short chain and loads of air in the shock so it never got to full travel / longest chain point.