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shortening chain

Discussion in 'Bicycle Mechanics' started by TOM, Apr 21, 2011.

  1. TOM

    TOM Maximum Pace

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    ...just got myself a chain connecting tool (the shimano TL-CN27) to try and fix chain slap by removing a link or two. Problem is I have never done this before and I'm an awful mechanic...:eek:

    * Chain is a brand-new Dura-Ace 10 Speed (when put on, I had a 11-28T cassette and my LBS had to make the chain longer - however, I'm no longer needing this wide-range cassette and reverted back to a standard 12-25T cassette. The chain is now too long and causing annoying chain slap over rougher parts in the road surface)

    * My big question is, where do I start with the "cutting"? Must I start with the "master link" and if so, do I need the chain connecting tool for that?

    Somewhere I read that you have to use pliers and apply force to the links on either side of the master link making sure it is on top of a loop...a bit confused here.
  2. Half-Fast Mike

    Half-Fast Mike Maximum Pace

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    TOM I have not used that tool - only the Topeak attachments on multitools. But I've successfully broken and joined and spliced many chains.

    I stay away from the master link.

    In your situation, I'd do this:

    Pop the chain off the crankwheel to release any tension from the derailleur.

    From the left side of the bike, pick a link and push the pin almost but not quite all the way out. If you pop it right out you'll find it really difficult to get back in. But if that does happen don't worry because you've another chance coming up! Once you have it just right the chain should come apart with a little wiggle. Shouldn't need pliers.

    Go along two pins (one whole link) and pop the pin out... or not depending on how successful you were with the above step.

    Now go round to the right side of the bike. Line up the broken ends and ease the pin back through.

    Check the link for stiffness. If it doesn't feel like the others, look carefully at the protruding ends and compare with neighboring links. Move it backward and forward with the tool as necessary until it frees up.

    Lube up, and off you go.
  3. Wolfman

    Wolfman Speeding Up

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    I would be careful with this. Just put the new link in and push it through with the device, then break off the excess with pliers, trying not to put too much leverage on either side of the links. If you do put too much force on, you end up with a knot in the chain - that is the links basically don't move and the chain will always skip when you pedal a rotation. I've done this.
  4. TOM

    TOM Maximum Pace

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    Thanks a lot Mike - very clear! (I think :eek:) Will try this evening.

    Will it be OK to push/ease the (same) link pin back through when connecting? There also seems to be a so-called "reinforced connecting pin" (アンプルタイプ コネクティングピン) which offers greater connecting strength...shouldn't I use this type instead?
  5. AlanW

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    Tom-san,
    Do NOT push out the "master link"! It is specially oversized and will permanently damage and weaken the chain. Leave it alone. Also you must use the reinforced connecting pin. Do not ease the old pin back in; push it all the way out and replace it with the reinforced one*.

    Here are the service instructions:
    http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Chain/SI_0450H_001/SI-0450H-002_en_du_ge_fr_v1_m56577569830686193.pdf

    New DA7900 chains are finicky because they are asymmetric and have to be joined a certain way. Logo should face outwards. Joining should be done as shown in "A" diagram of the service instructions.

    So:
    Put the chain on the two smallest cogs to reduce its tension.
    Pick the link you're going to cut at. Select the link so you end up with the chain as per the "A" diagram. Use the chain tool to push the pin all the way out. Retract the chain tool. At this point the chain will come apart.
    Confirm the length you need as shown in the service instructions.
    Take one end of the chain and use the chain tool again to push out the pin that removes as many links as you want. Probably 2 if you are going from a 28 to a 25. (Must be a multiple of 2).
    Retract the chain tool. The extra links will drop off.

    Take the two ends of the chain and put a new joining pin through them. The guide part will slide in easily. Last chance to check the orientation of everything!
    Take the chain tool and push the replacement joining pin all the way into the chain. You will feel a click as the pin slots into its proper position. Don't push it any further.
    Now take some pliers and break off the guide part of the pin.
    The link should move freely. If it does not, use the chain tool to nudge the new pin back ever so slightly, opposite to the way you pushed it in. Only a tiny bit, do not force it.

    Good luck.
    AW.

    * Shimano chains are made by peening over the ends of the pins. The pins are harder than the links. When you push out the pin it cuts a tiny ring of metal off the link as it goes, leaving the link hole oversized. The reinforced pins have a pronounced mushroom shape at each end which is sized just right to allow the link to deform elastically around it as it is pushed through, then click solidly into place.
  6. Half-Fast Mike

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    Didn't know that. Thanks AlanW. For what it's worth, I've never had any trouble. But your recommendations sound very sensible.

    Another option, TOM, might be the KMC Missing Link or similar. I use one of these on my Shimano 105 set-up. No problems so far, and it makes cleaning much easier as I can easily pop the chain off and get to the grimy bits.

    --Mike--
  7. TOM

    TOM Maximum Pace

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    Alan...thank you so much for having explained the entire process in such detail :)! Shimano ought to hire people like you !!!
    Also thanks for the Shimano "General Safety Information" PDF (but your explanation is 10 times better).

    Now that I know that I have to make an extra purchase (the reinforced connection pin) and therefore have to visit my LBS, I might as well ask the pros to do the job for me (but I will get some of those pins to try myself sometime in the future :(
  8. TOM

    TOM Maximum Pace

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    Thanks Mike ! I've been looking at these KMC chains, very attractive.
  9. AlanW

    AlanW Maximum Pace

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    Tom,
    You're welcome. Wouldn't want you to get stranded on one of your 250 km + rides :)

    I carry a couple of these pins and two spare links in my patch kit. So if my chain were to break I could cut out the damaged links completely and replace them. Never needed them so far (fingers crossed).

    Oh yes, they come in 9 speed and 10 speed as well so make sure you get the right ones!
  10. TOM

    TOM Maximum Pace

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    How very considerate of you Alan :)
    I will do the same henceforth!

  11. Sikochi

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    +1 I also carry some of the KMC links in my tool bottle kit (so easy to separate), but likewise haven`t needed them yet (touch wood). Hadn`t thought about spare links though...
  12. GSAstuto

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    One last small tip here - to get the right chain length, put your chain on the large -large combination, sans rear derailler. The length you want is 1 or 2 links overlap. Go for the 2 link overlap if you are running a fairly wide gear spread or the 1 link overlap if you're a corncob kinda guy. I think this also covered in the Shimano techdocs as well. P.S. the KMC master links work great! Makes cleaning and servicing your bike much easier.
  13. onm

    onm

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    Another tip, regarding the Shimano fitting pin thing;

    After you have snapped the end off it, making sure not to blind yourself with flying shrapnel, take a file to it and smooth it off. The side that is left is often very rough, and will not do any of your gear any favours.

    (Note the 'u' in favours).
  14. FarEast

    FarEast Maximum Pace Post Of The Week

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    I stopped using the "Master link" and "Quick Links" after destroying about 5 of them :eek:
  15. GSAstuto

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    Well, hell ya, for you 1000 watters, better stick with the extra duty pins! Especially on the smaller cogs - the chain tension is enourmous.
  16. TOM

    TOM Maximum Pace

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    Thanks

    everyone, esp. Alan, for all the great advice - very thankful :)! This forum has a wealth of experience.

    This morning I successfully (I think) shortened my chain by 2 links using the Shimano TL-CN27 chain connecting tool (very easy to use) and Dura-Ace Silver CN7801/6600 10S connecting pin.

    Although my chain is the latest Dura-Ace CN7901, I was told the CN7801 is compatible :confused:...so I tried.

    The most difficult part was snapping the end off - hard to find sufficient leverage but that's probably because I'm very clumsy at these things.

    After I got it snapped off, I tried the nudging both ends as strongly advised by Alan. Very tricky this part; the slightest protrusion on either side caused the chain to jump each time it passed through the rear derailleur. I ended up using three kinds of sandpaper to make both ends even :cool:.

    Can't wait now to test the shortened chain and see if the annoying chainstay slapping is gone. Will find out on tomorrow's extra-long mountain ride into Gunma !
  17. TOM

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    Thanks again...

    Alan's instructions encouraged me to do the job myself! Result...Dura-Ace at its very best! Enjoyed another 250k powerful mountain ride

    What a difference 2 mere links make!

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