sheldon's chain length guidelines

Discussion in 'Cycling Equipment' started by Jim Flom, Jan 27, 2003.

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  1. Jim Flom

    Jim Flom Guest

    I'm thinking that for racing, sheldon's guideline of threading the chain through the large-large
    combination (apart from the der) and adding a link would leave the chain too short for racers, who
    will find themselves in the large-large combination from time to time. Is there another suggestion
    for racers? Thanks.
     
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  2. Michael Dart

    Michael Dart Guest

    "Jim Flom" <[email protected]> wrote in message
    news:[email protected]...
    > I'm thinking that for racing, sheldon's guideline of threading the chain through the large-large
    > combination (apart from the der) and adding a link would leave the chain too short for racers, who
    > will find themselves in
    the
    > large-large combination from time to time. Is there another suggestion for racers? Thanks.

    Ummm...add 2 links?!

    HTH, Mike
     
  3. Jim Flom wrote:

    > I'm thinking that for racing, sheldon's guideline of threading the chain through the large-large
    > combination (apart from the der) and adding a link would leave the chain too short for racers, who
    > will find themselves in the large-large combination from time to time.

    What are you basing this on? What problem do you imagine will occur?

    > Is there another suggestion for racers?

    Actually, racers are less likely to do this than beginners are, 'cause a fair percentage of racers
    have a good understanding of how to use their gears most efficiently.

    By the way, I didn't invent this, I cribbed it from Shimano's official instructions, except that
    I had to correct a translation error...they said "2 links" actually meaning 2_ half_ links. A
    common error.

    My bikes that have double chainwheel setups are set with the chainline biased to permit use of all
    rear sprockets with the big ring, and that's how I set my chain length.

    Big/big is much less damaging than small/small.

    Sheldon "The Right Length Is The Right Length" Brown +------------------------------------------+
    | On Monday, when the sun is hot, | I wonder to myself a lot: | 'Now is it true, or is it not, |
    | 'That what is which and which is what?' | --A. A. Milne |
    +------------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone
    617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide
    http://captainbike.com http://sheldonbrown.com
     
  4. Pete Biggs

    Pete Biggs Guest

    Jim Flom wrote:
    > I'm thinking that for racing, sheldon's guideline of threading the chain through the large-large
    > combination (apart from the der) and adding a link would leave the chain too short for racers, who
    > will find themselves in the large-large combination from time to time.

    The aim of the one link extra is to leave the chain long enough for the large-large - so there's no
    problem whether you're racing or towing your granny home from the shops on roller skates.

    For more info/methods, see: http://www.parktool.com/repair_help/FAQchainlength.shtml

    ~PB
     
  5. David Kunz

    David Kunz Guest

    Pete Biggs wrote:
    > Jim Flom wrote:
    >
    >>I'm thinking that for racing, sheldon's guideline of threading the chain through the large-large
    >>combination (apart from the der) and adding a link would leave the chain too short for racers, who
    >>will find themselves in the large-large combination from time to time.
    >
    >
    > The aim of the one link extra is to leave the chain long enough for the large-large - so there's
    > no problem whether you're racing or towing your granny home from the shops on roller skates.
    >
    > For more info/methods, see: http://www.parktool.com/repair_help/FAQchainlength.shtml

    I find the my bike shifts much better with big-big + 1/2 link vs. + 1-1/2 link (that's my choice
    :)). I checked the big-big combo through the DR and it's tight, but not so tight that I'm worried
    about breaking or bending the DR. Night riding, I sometimes find myself in the big-big combo and I
    haven't noticed any problems. Of couse, when I realize that I've done that, I get out of it as soon
    as it's convenient. This may not be as easy when you're racing :).

    David
     
  6. On Mon, 27 Jan 2003 16:22:12 -0500, Sheldon Brown wrote:

    > Big/big is much less damaging than small/small.

    Hmm. If the chain is too short, then big-big = snap. But what is the danger of small-small, aside
    from greater stress on the chain itself from the mechanical advantage of that small chainring?

    --

    David L. Johnson

    __o | Become MicroSoft-free forever. Ask me how. _`\(,_ | (_)/ (_) |
     
  7. On Mon, 27 Jan 2003 15:37:58 -0500, Jim Flom wrote:

    > I'm thinking that for racing, sheldon's guideline of threading the chain through the large-large
    > combination (apart from the der) and adding a link would leave the chain too short for racers, who
    > will find themselves in the large-large combination from time to time. Is there another suggestion
    > for racers? Thanks.

    Why would this only matter to racers? But no, as long as there is adequate room in the large-large,
    then there is indeed adequate room. Adding a link should be enough for the derailleur. Personally, I
    test the length with the derailleur in there, just to make sure.

    I have used this method for decades. I have also been trained not to use the large-large combo, but,
    especially when tired, it happens. No bad consequences except for noisy operation.

    --

    David L. Johnson

    __o | When you are up to your ass in alligators, it's hard to remember _`\(,_ | that your initial
    objective was to drain the swamp. -- LBJ (_)/ (_) |
     
  8. A Muzi

    A Muzi Guest

    > On Mon, 27 Jan 2003 16:22:12 -0500, Sheldon Brown wrote:
    > > Big/big is much less damaging than small/small.

    "David L. Johnson >" <David L. Johnson <[email protected]> wrote in message
    news:[email protected]...
    > Hmm. If the chain is too short, then big-big = snap. But what is the danger of small-small, aside
    > from greater stress on the chain itself from the mechanical advantage of that small chainring?

    The chain can slip off the lower roller and, when it does, it brings the derailleur, sometimes
    already in pieces, up over the cassette until it smashes into the seatstay.

    --
    Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971
     
  9. You need to test for adequate chain length two ways-

    #1: With the chain in the largest rear cog and middle (or smallest if
    double) front chainring, shift to the largest front chainring.

    #2: With the chain in the largest front chainring and a middle-or-so rear
    cog, shift to the largest rear cog.

    The chain has to be able to pass *both* of these tests, and it's entirely possible that it could
    pass one and not the other.

    Ah, but you'll never, never, ever go into the large/large combination, right? Right. You're tired,
    it's 85 miles into a century and it's 97 degrees out, and the hill just got a bit steeper. So you
    just naturally go for your next-lower rear gear, not realizing that you're in your largest front
    chainring, and SNAP! It's not a pleasant sounds. It could be the derailleur pulling out of the
    hanger, it could be the hanger acutally snapping off the frame, it could be everything tossing
    itself into the wheel. Whatever it is, it's not worth the risk.

    --Mike-- Chain Reaction Bicycles http://www.ChainReaction.com

    "Jim Flom" <[email protected]> wrote in message
    news:[email protected]...
    > I'm thinking that for racing, sheldon's guideline of threading the chain through the large-large
    > combination (apart from the der) and adding a link would leave the chain too short for racers, who
    > will find themselves in
    the
    > large-large combination from time to time. Is there another suggestion for racers? Thanks.
     
  10. Sheldon Brown wrote:
    >
    > Jim Flom wrote:
    >
    > > I'm thinking that for racing, sheldon's guideline of threading the chain through the large-large
    > > combination (apart from the der) and adding a link would leave the chain too short for racers,
    > > who will find themselves in the large-large combination from time to time.
    >
    > What are you basing this on? What problem do you imagine will occur?
    >
    > > Is there another suggestion for racers?
    >
    > Actually, racers are less likely to do this than beginners are, 'cause a fair percentage of racers
    > have a good understanding of how to use their gears most efficiently.

    Well sure experienced racers will know it is not favorable, but that doesn't mean it doesn't happen,
    and quite intentionally at that. Racing is reactionary unless you are the one initiating. That means
    double shifts are sometimes forgone in practice in favor of the simpler and usually brief chain
    crossing. The key is the briefness -- if a low gear is anticipated for a more lengthy time, there
    will be a lower incentive to cross. Also, if the road is known/seen and by that it is known that the
    cross will be brief, then crossing will often be chosen over the cost of two double shifts and the
    possibility of dropping the chain -- which is a really bad thing to do at any key time in a race.
    Insurance is worth the cost of crossing and racers do it from time to time as a concious choice.

    I recognize that you never said racers *won't* do it (and beginners are sure to do it!), but I
    wanted to point out that it happens in racing and training for racing with fair frequency. I almost
    never cross my chain on fred rides. But for certain training ride courses and races, I do cross
    (big-big) the chain quite conciously. I can't say I like doing it, but I do it.

    Look at Eric Wohlberg at last year's Cat's Hill Crit (he was on fire -- he lapped the field solo and
    then dropped them again), which has a 23% grade. He big-ring'ed and crossed the chain *every* lap
    for the main purpose of simple gear selection and avoiding the dropped and mangled chain that is so
    *common* at that race.

    http://www.shutterfly.com/os.jsp?i=67b0de21b303fc45c43d
    http://www.shutterfly.com/os.jsp?i=67b0de21b3030e1f452e

    I was standing right beside the photographer at the top of the hill. Personally, I use a 53x46 w/ a
    12-24 cassette for that race and I do change rings for the hill.

    > My bikes that have double chainwheel setups are set with the chainline biased to permit use of all
    > rear sprockets with the big ring, and that's how I set my chain length.
    >
    > Big/big is much less damaging than small/small.

    You mean for your special setup?
     
  11. Mike Demicco

    Mike Demicco Guest

    On Mon, 27 Jan 2003 21:22:12 +0000, Sheldon Brown wrote:

    > Jim Flom wrote:
    >
    >> I'm thinking that for racing, sheldon's guideline of threading the chain through the large-large
    >> combination (apart from the der) and adding a link would leave the chain too short for racers,
    >> who will find themselves in the large-large combination from time to time.
    >
    > What are you basing this on? What problem do you imagine will occur?
    >
    >> Is there another suggestion for racers?
    >
    > Actually, racers are less likely to do this than beginners are, 'cause a fair percentage of racers
    > have a good understanding of how to use their gears most efficiently.
    >
    > By the way, I didn't invent this, I cribbed it from Shimano's official instructions, except that
    > I had to correct a translation error...they said "2 links" actually meaning 2_ half_ links. A
    > common error.

    What's wrong with leaving the chain a bit longer, so long as the derailler can still tension the
    chain when in the small-small combination? This has the added benefit of allowing you to put on a
    lower geared cassette without having to add links to the chain. I wouldn't do this on a mountain
    bike though - too much chain slap.
     
  12. Pete Biggs

    Pete Biggs Guest

    Mike DeMicco wrote:
    > What's wrong with leaving the chain a bit longer, so long as the derailler can still tension the
    > chain when in the small-small combination? This has the added benefit of allowing you to put on a
    > lower geared cassette without having to add links to the chain. I wouldn't do this on a mountain
    > bike though - too much chain slap.

    Bottom gear tends to work better when chain is as short as reasonably possible - especially when
    large cogs are used. The chain pulls the derailleur away from the cog. The 'b' screw can help - but
    only to a certain extent.

    ~PB
     
  13. Mike DeMicco wrote:
    >
    > On Mon, 27 Jan 2003 21:22:12 +0000, Sheldon Brown wrote:
    >
    > > Jim Flom wrote:
    > >
    > >> I'm thinking that for racing, sheldon's guideline of threading the chain through the
    > >> large-large combination (apart from the der) and adding a link would leave the chain too short
    > >> for racers, who will find themselves in the large-large combination from time to time.
    > >
    > > What are you basing this on? What problem do you imagine will occur?
    > >
    > >> Is there another suggestion for racers?
    > >
    > > Actually, racers are less likely to do this than beginners are, 'cause a fair percentage of
    > > racers have a good understanding of how to use their gears most efficiently.
    > >
    > > By the way, I didn't invent this, I cribbed it from Shimano's official instructions, except that
    > > I had to correct a translation error...they said "2 links" actually meaning 2_ half_ links. A
    > > common error.
    >
    > What's wrong with leaving the chain a bit longer, so long as the derailler can still tension the
    > chain when in the small-small combination? This has the added benefit of allowing you to put on a
    > lower geared cassette without having to add links to the chain. I wouldn't do this on a mountain
    > bike though - too much chain slap.

    I don't think this is too big of a deal in practice, but as Pete Biggs pointed out, the chain gap
    might not be quite as optimal if the chain is "too long," and this *may* (not for certain) impact
    shift performance for some gear changes. That said, I tend to adjust my chain for the biggest total
    wrap-up I expect to ever use, not what I use all the time. So I do think I suffer a tiny bit of
    shift performance hit (and only for certain gears) when using cassettes that are not necessarily
    synched with chain length.

    For example, on my older race bike with a DA 7402 (7402 IIRC) r-der, I ran a 12-21 cassette probably
    95% of the time. Occasionally I would want something like a 38-26 low for some rides and/or races.
    Naturally I needed to have chosen chain length for the 39-26 (or even 27 or 28) because there is
    more total wrap-up than for the 12-21 cassette w/ a 53-39 crank. Otherwise, changing gears would
    have involved the PITA change of chain length. Did this "compromise" affect shifting? I attributed a
    small amount of hesitation in the 53x17 to 53x19 w/ the 12-21 cassette to the non-optimum chain
    length, although I would admit that this is only a guess. Interestingly, Uniglide cogs worked better
    than HyperGlide for the 53x17 to 53x19 shift because the Uniglide teeth are _longer_ than HyperGlide
    teeth, and this tends to compensate for any chain gap that is a bit long. The UG teeth reach out and
    grab a distant chain better than HG teeth. For primo chain gap, HG is better with its gates. Chain
    gap is a fairly complex function of the spring tensions and geometrical dimensions of the r-der and
    chain length. I "guessed" at chain length as the cause of my "small amount of hesitation in the
    53x17 to 53x19" because of the fact that the UG cogs were undoubtably better performing than HG _for
    this specific scenario_ and the fact that chain gap is a complex function where one its parametrics
    is chain length.
     
  14. Jim Flom

    Jim Flom Guest

    "Sheldon Brown" <[email protected]> wrote in message
    news:[email protected]...
    >
    > What are you basing this on? What problem do you imagine will occur?

    Only just saw this post in it's entirety. At the time (before I actually tried it), I thought it
    might be too short to allow for the large-large combination once the chain had been threaded through
    the derailer. As you know, that's not the case. Now, having just had my bike in the shop, the
    wrenches commented that my chain is too short, and that I should fit the chain by going small-small
    and through the derailer, allowing the chain to just clear the pulley wheel. This high end shop says
    that's how they do their pro rigs and that's how I should do it too. I guess I'd be curious on any
    downside to my LBS's approach, as well as thoughts on whether the greater extension of the derailer
    when using the shorter chain would have any long term downside, i.e.., will it wear sooner, be more
    likely to go into the spokes, etc.

    Jim
     
  15. Jim Flom wrote:

    In response to somebody who was considering using a longer than necessary chain, I wrote:

    >>What are you basing this on? What problem do you imagine will occur?

    Jim Flom wrote:

    > Only just saw this post in it's entirety. At the time (before I actually tried it), I thought it
    > might be too short to allow for the large-large combination once the chain had been threaded
    > through the derailer. As you know, that's not the case. Now, having just had my bike in the shop,
    > the wrenches commented that my chain is too short, and that I should fit the chain by going
    > small-small and through the derailer, allowing the chain to just clear the pulley wheel. This high
    > end shop says that's how they do their pro rigs and that's how I should do it too.

    What are they basing this on? What problem do they imagine will occur?

    > I guess I'd be curious on any downside to my LBS's approach, as well as thoughts on whether the
    > greater extension of the derailer when using the shorter chain would have any long term downside,
    > i.e.., will it wear sooner, be more likely to go into the spokes, etc.

    Because racing bikes typically have such a narrow range of gearing, there's not likely to be any
    problem making the chain longer than necessary.

    I prefer to make it the right length. The weight of extra links doesn't really matter, but I see no
    advantage to adding them. Having useless parts on a bike displeases me aesthetically.

    Sheldon "Enough; No More" Brown +--------------------------------------------------------------+
    | Readers of a historical bent may be interested in my | great-grandfather's journal of life as
    | a sailor 1859-1869 | http://www.sheldonbrown.com/anders_junnila.html |
    +--------------------------------------------------------------+ Harris Cyclery, West Newton,
    Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts
    shipped Worldwide http://captainbike.com http://sheldonbrown.com
     
  16. Pete Biggs

    Pete Biggs Guest

    Jim Flom wrote:
    > Only just saw this post in it's entirety. At the time (before I actually tried it), I thought it
    > might be too short to allow for the large-large combination once the chain had been threaded
    > through the derailer. As you know, that's not the case. Now, having just had my bike in the shop,
    > the wrenches commented that my chain is too short, and that I should fit the chain by going
    > small-small and through the derailer, allowing the chain to just clear the pulley wheel. This high
    > end shop says that's how they do their pro rigs and that's how I should do it too. I guess I'd be
    > curious on any downside to my LBS's approach, as well as thoughts on whether the greater extension
    > of the derailer when using the shorter chain would have any long term downside, i.e.., will it
    > wear sooner, be more likely to go into the spokes, etc.

    There shouldn't be any major problems if bottom gear works ok.

    ~PB
     
  17. Jim Flom

    Jim Flom Guest

    The ever quotable Sheldon Brown wrote

    > Having useless parts on a bike displeases me aesthetically.

    I love this line. You have made my day, and it's only 8:50 AM.

    Jim Flom
     
  18. John Everett

    John Everett Guest

    On Fri, 31 Jan 2003 04:05:55 GMT, Sheldon Brown <[email protected]> wrote:

    > Having useless parts on a bike displeases me aesthetically.

    My thinking exactly as I happily ground the lawyer lips off each of my bikes, at least those that
    had them in the first place.

    jeverett3<AT>earthlink<DOT>net http://home.earthlink.net/~jeverett3
     
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