Help - chain catching seat stay

digitaria

I have made a few changes recently with the result that I'm not sure which is responsible for the following problem: - the chain is hitting the seatstay in top gear (smallest sprocket).

Bike is a Specialized Roubaix with a 9 speed Shimano mix.

The changes - new chain (swapped stock Shimano HG for SRAM with powerlink).
New wheels (swapped stock Alex rims for Fulcrum Racing 5s)
New chainset (swapped 105 triple for Tiagra compact double)
New front derailer - Ultegra.
Rear derailer is the original Ultegra.

The chain still turns in top gear, but it is making contact with the seat stay. So the required adjustment must be quite small. Can anyone tell me what I need to do to fix this? TIA

Uzbek

The derrailuer adjusting screw, check out this

http://www.parktool.com/repair/readhowto.asp?id=64



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If North Yorks Council spent as much on the roads each year as I do on my bike then I could spend less on my bike...

graemetherunner

what cassette have you on the new wheels?

If it didn't rub before then either you've change from a 11 to 12 tooth little sprocket (or 12 to 13 etc)...

I've a feeling this is whats happened as Fulcrum are made by campag... so they have a different (campag) lockring on them - even on the shimano versions & this lockring needs modification to fit a shimano 11 tooth sprocket. (this is how it was on a set of fulcrum R1's I fitted a while back)

pbiggs

Certainly try the derailleur limit screw - but that might be adjusted correctly already.

The cassette may be sitting slightly further out with the new wheel due to a slight difference in the design of the hub. Manufacturer's don't always make these things precisely correct.

If there is a shim or slim spacer that could be left out (?), try removing it.

Try a narrower chain if you can find a narrower 9-speed one. I can't remember how Shimano's compares to SRAM's.

A cassette with a smaller top sprocket may do the trick, but I wouldn't blame you for not wanting one.

<i>~Pete</i>

digitaria

Thank you all. Don't think derailleur adjustment is the answer since shifting on and off the smallest sprocket is fine. I did change the cassette - forgot to say (duh). The new cassette is 12-27 Ultegra, the old was 12-25 105 (I thought). I will have to find the old cassette and compare sizes.

Unknown

How about fitting very thin shim (<<1mm) on axle stub between nut and frame? this would fractionally move smallest sprocket away from seat stay and reduce rub; not too thick a shim though as this could reduce amount of axle in drop out; I`ve doen this in distant past successfully on 7/8 speed freewheels

JamesB MTB

digitaria

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by jamesb</i>

How about fitting very thin shim (<<1mm) on axle stub between nut and frame? this would fractionally move smallest sprocket away from seat stay and reduce rub; not too thick a shim though as this could reduce amount of axle in drop out; I`ve doen this in distant past successfully on 7/8 speed freewheels

JamesB MTB
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

I think that could work. It would only take a mm or so. Where would I get an appropriate shim? It's just an appropriately-sized metal washer we're talking about, right?

Unknown

"It's just an appropriately-sized metal washer we're talking about, right?"

Yes. And seems an obvious solution to me: as JamesB says a common fix when changing 7 to 8 - or 6 to 7 as I've done today. For 6 to 7 it changes relationship between rims and stays/brakes and requires re-dishing wheel, but in your case probably such a small change that will be o.k.

Opinion only!

d.j.
"Like a true nature's child,
We were born,
Born to drink mild"

pbiggs

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by digitaria</i>

Thank you all. Don't think derailleur adjustment is the answer since shifting on and off the smallest sprocket is fine.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">That doesn't prove the derailleur isn't shifting further than necessary from the top sprocket. You may be able to limit it more and still have it working fine. I know from experience that's it's worth a try.

Tighten the derailleur's limit screw until the chain clatters, then back off so it just stops clattering. This doesn't affect indexing of the rest of the gears - that's down to cable tension.

mrdsgs

surely the prob;lem was caused by going from triple to double chainset, thereby altering chainline inwards on large ring unless a compenating shorter bb was also used.

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