New sprocket new chain - binding - familiar?

Ello. Been buildin me new bike. Got a problem I aint had before, and I've built five of 'em now...

Got a new sprocket on back - a Surly 19T - and a new Izumi ESH chain. The sprocket teeth and chain mesh so frikkin tightly that they cause binding when the drivetrain rotates, f-ing up chain tension, making a noise, causing friction and generally pissin me off. Even when you take the two components off the bike and just try engaging them manually, they stick a bit.

I've had to chuck an old 18T on the back, which I had hanging around. Lower quality than the Surly, thinner metal, but it works no problem. Geared a bit high now but I'll get over it. Honest.

So, anyone encountered this problem before? Surly sprockets so butch and chunky their teeth refuse to participate with anything but the broadest chains? Izumi ESH built to such exacting NJS tolerances that unless mounted on a genuine keirin frame they will conspire to subvert the build and do yer head in?

Before you ask, the chain and sprocket are both 1/8 and the chainline is good to +/- 1mm.

Cheers. Olly.

Sounds like an odd one Olly. You say that both chain and sprocket are definitely both 1/18 width, and I presume 1/2" pitch. When you engage them off the bike how are they binding - does the chain not sit deeply enough into the sprocket? Have you got another chain around - does the sprocket work with that? Also, you say it fucks up the chain tension - in what way; what happens?

Chain sits deep enough, but it's tight, like the teeth could do with being a few microns thinner. So you gotta give it a tug to get it out again. Yuh they're both 1/2" pitch unless someone is really having a laugh at my expense. Haha. No, they are. Haven't tried with another chain, that's good idea though. It buggers the chain tension because at the point the chain meets the sprocket, the links don't sit nicely in the teeth, so you can't get it genuine tension. Strange, as I said I ain't seen nothing like it before.

Is the Surly sprocket plated/coated with something that makes it slightly wider?

Heh, I just had this with a new 3/32 sprocket from VeloSolo... my old cog from planetx was pretty thin and didnt have enough teeth on it so i decide to purchase another. Got this one out of the packet and saw it was a lovely chunky piece of engineering and very shiny and gold (im a wannabe hipster), however the chain wont interface with the cog at all. Spent about half an hour trying to work out what I had done wrong and then concluded the teeth on the sprocket were just too damn wide. Will have to send it back and seek another of a decreased width I guess, 19t are tricky to come by though.

The gold one is the new one... tis substantially chunkier than the old one.

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looks like a 1/8th

what do you mean "looks like"?? it bloody is!

Ha!

looks like a 1/8th

Either that, or the other one's 1/16"

i was being diplomatic, breaking it gently for him :)

Either that, or the other one's 1/16"

Heh, funnily enough thats actually closer, the planetx one seems very skinny.

The new one has 3/32 written on the side and measured with calipers it is EXACTLY 3/32. The problem being that so are the holes in the chain, hence the interference fit... Will visit the LBS tommorow and borrow a new 3/32 chain to make sure i'm not just being stupid and have a funny chain.

Still the customer service people are ever so nice. Will send it back if a new chain dont do the trick.