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Thread: Sachs chains.

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    Jubalayo Unogwaja! Bokkie's Avatar
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    Sachs chains.

    I was at the lbs this afternoon and I got talking with one of the mechs about chains and he too knew all about the 'Sheldon' chain calculation, ie., big-big no derailleur, + 1 link. We looked at new Cannondale Gemini 900, and pontificated for a while. We both agreed the Gemini chain looks too long though we did not actually remove the chain and resize it Sheldons way.

    He came close to doing so, but the big cohuna (boss man) did not want him/me messing around with a new bike. B*s*a*d!

    So we mused some more and I asked him, if I buy a new chain (Sachs PC99) and I shorten it, fit to my Gemini 1000 but make a botch of it, can I use more than one master link on the chain to get the length right afterwards?

    In other words, I'd have potentially 2 pieces of chain, 1 master link would have been used anyway, bit would a second be ok, or would I use a more 'permanent' fixing?
    If your bollocks ain't sore, yer ain't on yer boike!

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    I would think the 'smarter' way would be to err on the side of making it too long and then shortening it to suit.Too long will cause no problems other than some possible drag on the rear dreailer when in the small ring and some of the smaller cogs, or slap on the chainstay. It is just noise that hurts nothing and tells you not to go there or to shorten the chain.

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    Mr. Cellophane RainmanP's Avatar
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    I agree with Pokey. From time to time I may fool around with the gearing on one of my bikes, trying to decide whether to put on a really big cog for an anticipated extra hilly ride or put on my usual 23-25 big cog. I leave the chain 4-5 links too long and ride it that way with no problem, sometimes for several weeks. You DO NOT want your chain too short. With a too short chain you can get onto a too tight gear combination that puts so much tension on the chain you can't shift off and it may be so tight you can't even turn the pedals. Ask me how I know this. You have to stop and loosen the wheel, which itself becomes extremely difficult, in order to get the chain back onto a smaller cog. Believe me, there is nothing to be gained from trying to absolutely minimize chain length, even if you are a racer trying to cut that extra couple of grams a chain link weighs.
    If it ain't broke, mess with it anyway!

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    Jubalayo Unogwaja! Bokkie's Avatar
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    Thanks guys. I appreciate the sound advice.
    If your bollocks ain't sore, yer ain't on yer boike!

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    How do you "botch" removing links?
    Even a trained chimpanzee should be able to learn how to use a chain tool in about 5 minutes!
    Je vais à vélo, donc je suis!

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    feros ferio John E's Avatar
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    Sheldon's system sounds about right to me, but be sure to try a few GENTLE test shifts into large-large on a shop stand (or using a friend as a shop stand) before riding. Short-chaining does allow you to stretch any given rear derailleur's takeup capacity, but I think it's simply too risky for cycling in traffic.
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    Gone, but not forgotten Sheldon Brown's Avatar
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    I was at the lbs this afternoon and I got talking with one of the mechs about chains and he too knew all about the 'Sheldon' chain calculation, ie., big-big no derailleur, + 1 link.
    I can't take credit for this, it's the Official Shimano recommendation, comes with the data sheet supplied with their rear derailers...only thing is that they say "2 links" but this is probably a translation error...they mean 2 half-links, or 1 actual complete link.

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    Jubalayo Unogwaja! Bokkie's Avatar
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    How do you "botch" removing links?
    Are you saying I'm dumber than a chimpanzee?

    Let me explain what I meant by bodging it. If, in the pursuit of knowledge, I remove a longer length of chain than I intended, then I'd have two bits to rejoin if I want to rectify the mistake. I was interested in knowing another master link would do, or if I should make the link more permanent.

    Sure, any chimp can break a chain, but when you've got a 147 links or so, not all chimps will break it in the right place everytime. How many times have you ever cut a piece of wood for example and found you cut it 1" too short? Or you left it 1" to long. Any chimp can use a saw.
    If your bollocks ain't sore, yer ain't on yer boike!

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    Jubalayo Unogwaja! Bokkie's Avatar
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    I can't take credit for this, it's the Official Shimano recommendation...
    Come on, Sheldon, you ain't fooling me on that one! I looked at your website, and how shall I say it, there was, um, a lot of very, very good advice and information on just about everything there is to do with bikes. Yours are not the ramblings of a theorist, you know that, I know that, so darned well take the credit!
    If your bollocks ain't sore, yer ain't on yer boike!

  10. #10
    Senior Member (Retired) gmason's Avatar
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    How many times have you ever cut a piece of wood
    Damn ... cut it twice, and it's still too short!

    Cheers...Gary

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    Mr. Cellophane RainmanP's Avatar
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    ROTFLOL!!

    Originally posted by gmason


    Damn ... cut it twice, and it's still too short!

    Cheers...Gary
    If it ain't broke, mess with it anyway!

  12. #12
    Senior Member pat5319's Avatar
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    Why not just cut the chain so it just clears the rear derailleur pulleys/cage in the small cog/small chainring combination? You can use (just about) any size casette/freewheel; no problems, no adding or cutting links. By having the chain long by some standards you- put less stress on the derailleur spring(s)-enhancing its/their lifetime and reduce friction- negating the negative effects of any excess weight ( "Eddy B." - Bicycle Racing) among others.

    Ride Simply
    Pat
    Pat5319


  13. #13
    Gone, but not forgotten Sheldon Brown's Avatar
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    Why not just cut the chain so it just clears the rear derailleur pulleys/cage in the small cog/small chainring combination? You can use (just about) any size casette/freewheel; no problems, no adding or cutting links. By having the chain long by some standards you- put less stress on the derailleur spring(s)-enhancing its/their lifetime and reduce friction- negating the negative effects of any excess weight ( "Eddy B." - Bicycle Racing) among others.
    With the tight-ratio clusters Eddy B's proteges used, that works.

    With wide-range gearing, however, this can lead to damage if the rider accidentally shifts into the large/large gear. Large/large is the critical case.

    See also my Derailer Adjustment article.

    All the best,

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  14. #14
    Senior Member pat5319's Avatar
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    OK, so I forgot to mention to test it in the large/large combo and that there would be someone who wouldn't. You just need to be sure you have the right size ( long enough) derailleur pulley cage.

    I've used this technique on HUNDREDS of touring bikes, mountain bikes, road bikes with triples etc. with success in all cases with no damage whatsoever, I have had to reccomend longer reach derailleurs, ( before damage), to those who had tried to use short reach when converting to triples etc.

    Note: This technique gives you the MAXIMUM chain length you can use and still have tension on the chain in the small/small combo. This maximum length gives the most flexibilty when using more than one size cassette/freewheel. If it doesn't work for you you will NEED a longer derailleur cage.


    Oh, Sheldon- This is a proven technique - Scientific Method and I learned it from a guy who used to work with Albert Eisentraut among others

    Ride Simple and Smart
    Pat
    Last edited by pat5319; 09-11-02 at 12:42 AM.
    Pat5319


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