Usable gears on 53,39 x 25,12 9 speed?

Discussion in 'Cycling Equipment' started by Billx, Apr 21, 2003.

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  1. Billx

    Billx Guest

    On a new Shimano Ultegra transmission with 53,39 up front and 12-25 9 speed rear how many gear
    combinations should I expect to be possible without derailer/chain rub? Right now the 39 will only
    run 4-5 of the 9 rear gears without rubbing and the bike is brand new. Suspect the shop hasn't
    adjusted the derailerst beyond factory settings and that a greater gear range is possible.
     
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  2. "BillX" <[email protected]> wrote in news:[email protected]:

    > On a new Shimano Ultegra transmission with 53,39 up front and 12-25 9 speed rear how many gear
    > combinations should I expect to be possible without derailer/chain rub? Right now the 39 will only
    > run 4-5 of the 9 rear gears without rubbing and the bike is brand new. Suspect the shop hasn't
    > adjusted the derailerst beyond factory settings and that a greater gear range is possible.

    On the Shimano Ultegra STI front brifter, there is an indexed 'click' in between the indexed
    'click's for your small and large chainrings. This is so that you can use those hard to reach gears.

    With that cassette, about the only combos you dont' want to use are 53-25 or 39-12. You should be
    able to reach the rest of them no problem using the "trim" setting described above.

    Just my $0.02.
     
  3. On Mon, 21 Apr 2003 22:14:43 +0000, BillX wrote:

    > On a new Shimano Ultegra transmission with 53,39 up front and 12-25 9 speed rear how many gear
    > combinations should I expect to be possible without derailer/chain rub? Right now the 39 will only
    > run 4-5 of the 9 rear gears without rubbing and the bike is brand new. Suspect the shop hasn't
    > adjusted the derailerst beyond factory settings and that a greater gear range is possible.

    Several things. Yeah, if the derailleur rubs on the chain with half the cogs in the back, it's not
    adjusted well. Some shifters have a "trim" capability, so you can click it a little to the right, to
    take care of this. This is good, since the alternative is a more complicated derailleur cage that
    IMO will not shift as well. Check your dealer on that.

    Secondly, how many gears do you think you have? Here are the gear ratios for a standard 700c wheel
    and 23mm tire, in "gear-inches".

    53: 115.4 106.6 99.0 92.4 81.5 72.9 66.0 60.2 55.4

    54: 85.0 78.4 72.8 68.0 60.0 53.7 48.6 44.3 40.8

    So, you see that the largest 4-5 combinations with the 39, the ones that are rubbing, are all
    duplicated with the other chainring, and without using the 53/25, which you should avoid. OK, the 85
    and 78 are not available, but the 81.5 is close enough, and no one can use the 39/12 without it
    rubbing on the outer ring. That's another combination to avoid.

    Really you have a 12-speed, 13 if you could use the 39/13. This is not a set-up problem, but a
    design decision that you can write Shimano about.

    --

    David L. Johnson

    __o | Become MicroSoft-free forever. Ask me how. _`\(,_ | (_)/ (_) |
     
  4. "BillX" <[email protected]> wrote in message news:[email protected]...
    > On a new Shimano Ultegra transmission with 53,39 up front and 12-25
    9 speed
    > rear how many gear combinations should I expect to be possible
    without
    > derailer/chain rub? Right now the 39 will only run 4-5 of the 9
    rear gears
    > without rubbing and the bike is brand new. Suspect the shop hasn't
    adjusted
    > the derailerst beyond factory settings and that a greater gear range
    is
    > possible.

    I sometimes run a similar setup (51x38 or 39) with 12-25 in back and I think I can get 8 cogs on the
    back on the small ring with no rubbing.

    JT

    --
    *******************************************
    NB: reply-to address is munged

    Visit http://www.jt10000.com
    *******************************************
     
  5. "David L. Johnson" <[email protected]> wrote in message
    news:[email protected]...
    > On Mon, 21 Apr 2003 22:14:43 +0000, BillX wrote:
    >
    > > On a new Shimano Ultegra transmission with 53,39 up front and 12-25 9
    speed
    > > rear how many gear combinations should I expect to be possible without derailer/chain rub? Right
    > > now the 39 will only run 4-5 of the 9 rear
    gears
    > > without rubbing and the bike is brand new. Suspect the shop hasn't
    adjusted
    > > the derailerst beyond factory settings and that a greater gear range is possible.
    >
    > Several things. Yeah, if the derailleur rubs on the chain with half the cogs in the back, it's not
    > adjusted well. Some shifters have a "trim" capability, so you can click it a little to the right,
    > to take care of this. This is good, since the alternative is a more complicated derailleur cage
    > that IMO will not shift as well. Check your dealer on that.
    >
    > Secondly, how many gears do you think you have? Here are the gear ratios for a standard 700c wheel
    > and 23mm tire, in "gear-inches".
    >
    > 53: 115.4 106.6 99.0 92.4 81.5 72.9 66.0 60.2 55.4
    >
    > 39: 85.0 78.4 72.8 68.0 60.0 53.7 48.6 44.3 40.8
    >
    > So, you see that the largest 4-5 combinations with the 39, the ones that are rubbing, are all
    > duplicated with the other chainring, and without using the 53/25, which you should avoid. OK, the
    > 85 and 78 are not
    available, but
    > the 81.5 is close enough, and no one can use the 39/12 without it rubbing on the outer ring.
    > That's another combination to avoid.
    >
    > Really you have a 12-speed, 13 if you could use the 39/13. This is not a set-up problem, but a
    > design decision that you can write Shimano about.
    >
    >

    It's not a design problem. It's easier to shift (especially when under load) the rear cogs. When in
    one chainring it is preferable to stay in that ring until you run out of rear gears for that ring.

    For the 39 ring you should be able to use all the cogs except the two smallest ones (from 14 to 25),
    maybe even the second last one (the 13) but if you couldn't that wouldn't be unreasonable. Only
    being able to use 4-5 cogs is not a normal situation.

    For the rear you should be able to use all but the largest one (from the 12 to the 23).
     
  6. Ritch

    Ritch Guest

    "BillX" <[email protected]> wrote in message news:<[email protected]>...
    > On a new Shimano Ultegra transmission with 53,39 up front and 12-25 9 speed rear how many gear
    > combinations should I expect to be possible without derailer/chain rub? Right now the 39 will only
    > run 4-5 of the 9 rear gears without rubbing and the bike is brand new. Suspect the shop hasn't
    > adjusted the derailerst beyond factory settings and that a greater gear range is possible.

    Sounds about right to me... you might want to use the fine tuning knobs while you are on the move.
    If they are at their limit, you'll need to adjust the fd. Don't worry, you haven't wasted your money
    (at least not for this reason).

    Ritch
     
  7. On Mon, 21 Apr 2003 21:49:18 +0000, one of the six billion wrote:

    > It's not a design problem. It's easier to shift (especially when under load) the rear cogs.

    This sounds like a software company: "It's not a bug, it's a feature." Sure, it's easier to shift
    the rear. But that doesn't mean you plan your gears around what works without proper technique. You
    get the gears that give you the range and steps you want, and you learn how to shift into them.

    If you have to shift while climbing (where this all really matters), drop off the load for a second.
    This will allow you to shift either the chainring or the rear.

    > When in one chainring it is preferable to stay in that ring until you run out of rear gears for
    >that ring.

    Why? This is the line that Shimano -- and Campy -- offer, but there is no reason for it. If you want
    to claim you can shift under even heavy load, then, yeah, the rear works better. But there is no
    need to do that. On a short hill, remember that it takes the same amount of energy no matter what
    gear you are in, and grunt it out. On a long hill, plan ahead. Or back off the load to shift. But
    the equipment manufacturers do not want to suggest that you have to use technique to use their
    equipment properly, so they restrict the range and/or selection of gears that they offer so
    technique no longer matters.

    --

    David L. Johnson

    __o | Enron's slogan: Respect, Communication, Integrity, and _`\(,_ | Excellence. (_)/ (_) |
     
  8. Billx

    Billx Guest

    Boyd Speerschneider wrote in message ...
    >On the Shimano Ultegra STI front brifter, there is an indexed 'click' in between the indexed
    >'click's for your small and large chainrings. This is so that you can use those hard to
    >reach gears.
    >
    >With that cassette, about the only combos you dont' want to use are 53-25 or 39-12. You should be
    >able to reach the rest of them no problem using the "trim" setting described above.
    >
    >Just my $0.02.

    How do I get into this in between indexed setting? This is the first bike I've owned with shifting
    built into the brake levers. Previous bike was six speed indexed on down tube. Because the front
    wasn't indexed I never had a problem with cross chaining rubbing the front derailer.
     
  9. Sam Huffman

    Sam Huffman Guest

    "BillX" <[email protected]> writes:

    > Boyd Speerschneider wrote in message ...
    > >On the Shimano Ultegra STI front brifter, there is an indexed 'click' in between the indexed
    > >'click's for your small and large chainrings. This is so that you can use those hard to
    > >reach gears.
    > >
    > >With that cassette, about the only combos you dont' want to use are 53-25 or 39-12. You should be
    > >able to reach the rest of them no problem using the "trim" setting described above.
    > >
    > >Just my $0.02.
    >
    > How do I get into this in between indexed setting? This is the first bike I've owned with shifting
    > built into the brake levers. Previous bike was six speed indexed on down tube. Because the front
    > wasn't indexed I never had a problem with cross chaining rubbing the front derailer.

    Give the front shifter a nudge, not a full push. You should hear a slight
    click.

    On my Ultegra-triple setup it took me a couple weeks before I could reliably get the trim instead of
    the full shift. I don't know if that was because I had to learn how to do it, or because the
    mechanism had to break in.

    I still don't have what I'd consider "good" front shifting, where "good" is the non-indexed downtube
    shifting I previously used "good". On that bike I could get to 8 of the 9 cogs from either ring
    without rubbing. Now it varies between 6 and 7, depending on the ring I'm on.

    Sam
     
  10. J. Matt

    J. Matt Guest

    "BillX" <[email protected]> wrote in message news:<[email protected]>...
    > On a new Shimano Ultegra transmission with 53,39 up front and 12-25 9 speed rear how many gear
    > combinations should I expect to be possible without derailer/chain rub? Right now the 39 will only
    > run 4-5 of the 9 rear gears without rubbing and the bike is brand new. Suspect the shop hasn't
    > adjusted the derailerst beyond factory settings and that a greater gear range is possible.

    Hello Bill

    I just built up a bike with a new Ultegra Group, with identical gearing to yours. Indeed, the 39
    can only run 4 or 5 of the gears without rubbing, but on my bike at least (a 60cm Gunnar Roadie),
    the chain line rather than the derailleur is the cause, meaning the chain rubs on the big ring
    because of the angles involved when the bike is geared in the 39 up front and anything below the 15
    or 17 in back.

    It's simply meant that I have had to adjust my riding style, using the 53 more often, even up to the
    23. The chainline is fine on the 53/23 combo, leading me to think that this is by design. First, the
    bike is marketed as a race bike, meaning it's meant to be ridden fast. It makes sense then, that the
    big ring would be the primary ring up front, and the 39 used less often for warm-up, cool-down or
    sustained climbing.

    Anyway, if you figure out the gear ratios, you're not losing any unique gears by the limitation. And
    if aggressive gearing does not suit your riding style, a switch to a triple on the Ultegra only
    requires a new bottom bracket, crank, and rear derailleur.

    Best,

    John M.
     
  11. chris_gr

    chris_gr New Member

    Joined:
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    I was also wondering which combos are un-usable. I have a tribike with 650 wheels and 55/42 front and a 11-23 in the back. When in the 42-12 combo the chain rubs the 55T ring. I thought it was unusual to have 2 noisy cogs in the back but from this discussion it sounds pretty normal.
     
  12. Mike S.

    Mike S. Guest

    "chris_gr" <[email protected]> wrote in message
    news:[email protected]...
    > Billx wrote:
    > > On a new Shimano Ultegra transmission with 53,39 up front and 12-25 9 speed rear how many gear
    > > combinations should I expect to be possible without derailer/chain rub? Right now the 39 will
    > > only run 4-5 of the
    9
    > > rear gears without rubbing and the bike is brand new. Suspect the shop hasn't adjusted the
    > > derailerst beyond factory settings and that a greater gear range is possible.
    >
    >
    >
    > I was also wondering which combos are un-usable. I have a tribike with 650 wheels and 55/42 front
    > and a 11-23 in the back. When in the 42-12 combo the chain rubs the 55T ring. I thought it was
    > unusual to have 2 noisy cogs in the back but from this discussion it sounds pretty normal.
    >

    You should always avoid big/big and small/small combos. Bad for things... That rubbing sound y'all
    hear is the chain rubbing on the either the big ring or the outer cage of the f. der. Sometimes it
    is an adjustment thing, most often people are riding in gears that their bike doesn't like...

    There are overlapping gears in your c-ring/cassette. I generally shift down a few (3-4) cogs while
    in the small ring, then shift to the big ring and back up a gear or two to get roughly the same gear
    I was just in. Once you get past the middle (going towards physically smaller gears) of the
    cassette, its better to be in the big ring. Vice versa when you're going back up the cassette.

    So, to answer the specific question you'll have to go look up a gear inch chart to see exactly how
    many discrete gears there are after removing overlap.

    Having said that, if you surf on over to Sheldon Brown's site, he probably explains everything over
    there a lot better than we're going to...

    That help?

    Mike
     
  13. On Sat, 27 Sep 2003 01:14:07 +0950, chris_gr wrote:

    > Billx wrote:
    > > On a new Shimano Ultegra transmission with 53,39 up front and 12-25 9 speed rear how many gear
    > > combinations should I expect to be possible without derailer/chain rub? Right now the 39 will
    > > only run 4-5 of the 9 rear gears without rubbing and the bike is brand new. Suspect the shop
    > > hasn't adjusted the derailerst beyond factory settings and that a greater gear range is
    > > possible.

    So, it's the chain rubbing on the derailleur cage? That is an adjustment or user error. Most new
    Shimano, and all Campy, front shifters have some trim adjustment -- a mini-click that does not move
    the chain, but moves the cage a bit to better center it around the chain. If that doesn't help, talk
    to the shop people.
    >
    > I was also wondering which combos are un-usable. I have a tribike with 650 wheels and 55/42 front
    > and a 11-23 in the back. When in the 42-12 combo the chain rubs the 55T ring. I thought it was
    > unusual to have 2 noisy cogs in the back but from this discussion it sounds pretty normal.

    Well, this is more normal. You might be able to avoid it by adding spacers between one of the rings
    and the spider. But you have to be careful, too much space and the chain could get snagged in
    between. But the small-second smallest combination is probably the same ratio as a more reasonable
    combination with the big ring.

    --

    David L. Johnson

    __o | "What am I on? I'm on my bike, six hours a day, busting my ass. _`\(,_ | What are you on?"
    --Lance Armstrong (_)/ (_) |
     
  14. Sounds about right, You can calculate the gear inches, or use Sheldon Brown's gear calculator.
    http://www.sheldonbrown.com/gears/ Once you see the chart, you probably only need to use the 19-
    25 with the
    39t.You shouldn't have a problem with chain/derailleur rub unless you go beyond this. At least I
    don't with my 53/39 Ultegra 12-27 9sp. -tom

    > > Billx wrote:
    > > > On a new Shimano Ultegra transmission with 53,39 up front and 12-25
    9
    > > > speed rear how many gear combinations should I expect to be possible without derailer/chain
    > > > rub? Right now the 39 will only run 4-5 of
    the
    > > > 9 rear gears without rubbing and the bike is brand new. Suspect the shop hasn't adjusted the
    > > > derailerst beyond factory settings and that
    a
    > > > greater gear range is possible.
     
  15. Nick Burns

    Nick Burns Guest

    "Mike S." <[email protected]> wrote in message

    >
    > You should always avoid big/big and small/small combos. Bad for things... That rubbing sound y'all
    > hear is the chain rubbing on the either the big ring or the outer cage of the f. der. Sometimes it
    > is an adjustment
    thing,
    > most often people are riding in gears that their bike doesn't like...
    >
    > There are overlapping gears in your c-ring/cassette. I generally shift
    down
    > a few (3-4) cogs while in the small ring, then shift to the big ring and back up a gear or two to
    > get roughly the same gear I was just in. Once
    you
    > get past the middle (going towards physically smaller gears) of the cassette, its better to be in
    > the big ring. Vice versa when you're going back up the cassette.
    >

    That depends on the terrain you live in (and the gears you are using). I found that since I moved to
    this area with rolling terrain, I wanted to be in the big ring most of the time and I am using the 9
    smallest cogs (on a 10v system). before I moved, I lived near the coast and was either on flat
    terrain or climbs of at least 4 percent. While there, my habits were about as you descibed. The same
    comments apply to a race course that is rolling, vs all flats or with climbs.

    The bottom line is that a road bike should be able to use all but the big\big and small\small. The
    Camag 10v systems are so smooth, you can use the big\big without noticing any additional roughness,
    although that does not make it a good idea. I am just pointing out that someone oly expecting to use
    5 cogs per ring has set his or her sites too low.
     
  16. Chris-<< When in the 42-12 combo the chain rubs the 55T ring. >><BR><BR>

    No surprise there. If you start form a stop light in third gear in tyour car, it won't work well
    either. Shift into the big ring and up a few cogs to get the same ratio, w/o noise.

    Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
    (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"
     
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