different chain rings on Shimano road double and triple cranks

Discussion in 'Cycling Equipment' started by Byron Sheppard, Dec 25, 2003.

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  1. Two questions:

    1) Does anyone know why Shimano puts different rings on road triples than on road doubles? Doubles
    seem to come with 53/39 combos, while triples come with 52/42/30. This seems odd to me; why not
    just add a third ring and leave the other two the same? Is it a silly marketing thing, or is
    there a good technical reason for this?

    So of course, I'd like to change the rings on a recently acquired Ultegra triple to 53/39/30 (or
    perhaps even a 28 small ring). My LBS tells me that the rings are actually different and that such a
    change would be "difficult." So...

    2) Is this true, or can I easily change my triple rings to double rings?

    And question 3 of my two questions: if I have the long cage Ultegra derailleur, can I use an old
    (unused) 28 Shimano MTB ring I have kicking around, or is the small ring road specific?

    thanks, byron
     
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  2. daveornee

    daveornee New Member

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  3. byron-<< 1) Does anyone know why Shimano puts different rings on road triples than on road doubles?
    Doubles seem to come with 53/39 combos, while triples come with 52/42/30. This seems odd to me; why
    not just add a third ring and leave the other two the same? >><BR><BR>

    With a well set up triple, where you can use the middle with the entire cogset range, a 42 is more
    useable than a 39, IMO, YMMV.

    byron<< So of course, I'd like to change the rings on a recently acquired Ultegra triple to 53/39/30
    (or perhaps even a 28 small ring). My LBS tells me that the rings are actually different and that
    such a change would be "difficult." >><BR><BR>

    If you use a 39t with pickup pins and ramps it will work fine, use a TA. If you just put a road 39t
    on there, it may not shift well as shimano triples really rely on the pins and ramps.

    bryon- << if I have the long cage Ultegra derailleur, can I use an old (unused) 28 Shimano MTB ring
    I have kicking around, or is the small ring road specific? >><BR><BR>

    if it is 74mm BCD, it'll work.

    Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
    (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"
     
  4. > 1) Does anyone know why Shimano puts different rings on road triples than
    on
    > road doubles? Doubles seem to come with 53/39 combos, while triples come with 52/42/30. This seems
    > odd to me; why not just add a third ring and
    leave
    > the other two the same? Is it a silly marketing thing, or is there a good technical reason
    > for this?

    The most difficult front shift of all is moving from the middle chainring (on a triple) down to the
    smallest. The problem is mostly due to the height of the front derailleur over the chainring; the
    further it is from the "action", the less-efficient it is at moving the chain. Thus is it *much*
    easier for a derailleur to shift off of a 52/42/XX option than from a
    53/39/XX. The 53/39 requires that the front derailleur to high enough to clear an additional 4
    teeth (53-39=14t differences, vs 52-42=10t).

    That's the reason why, despite all the fancy stuff they've done to the inside plate of the DuraAce
    triple front derailleur, the Ultegra triple absolutely, positively makes the shift from middle to
    smallest better.

    Please note that you can change the smallest chainring with no ill effects, since the difficult
    shifts are the ones going to a smaller chainring (going "down") and the inside chainring is already
    as "down" as you can get.

    > So of course, I'd like to change the rings on a recently acquired Ultegra triple to 53/39/30 (or
    > perhaps even a 28 small ring). My LBS tells me that the rings are actually different and that such
    > a change would be "difficult." So...
    >
    > 2) Is this true, or can I easily change my triple rings to double rings?

    If you simply switch your 42t triple middle to a 39 that's designed for a double, you're going to
    have a pretty nasty-shifting setup, for two reasons. First, for the reason I gave above (that the
    bigger difference between middle & large chainring puts the derailleur in a less-optimal position),
    and second, because you'd be using a "middle" chainring with no shifting pins/ramps on the inside
    surface, which are designed to make it easier to shift from smallest to middle.

    As Peter noted in this thread, TA does make a 39t 130mm bolt pattern chainring that's designed to be
    used as the middle chainring in a triple environment.

    > And question 3 of my two questions: if I have the long cage Ultegra derailleur, can I use an old
    > (unused) 28 Shimano MTB ring I have kicking around, or is the small ring road specific?

    If it's a 74mm bolt pattern, no issue.

    Please note, regarding the change from 42 to 39t middle, that we have customers who do this all the
    time, insisting that it should work just fine and we're just trying to spoil their fun. I'd say at
    least 75% of those people come back to us, telling us that we were right, it doesn't shift as well
    as they'd like (and can we please fix it somehow?). Another 15% say it doesn't work quite as well,
    but they can deal with it. And 10% think there's no difference.

    It's truly amazing, though, how many people change their middle chainring and insist that any
    problem with shifting is a result of something else (bad chain is a popular one, frame alignment
    another). But switch back to the stock chainring and those "defects" go away. Hmmm...

    --Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com
     
  5. meb

    meb New Member

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    That explains why standard road triples went to a 10T difference.
    Why 52/42 instead of say 53/43 or 54/44?
     
  6. "meb" wrote:
    > That explains why standard road triples went to a 10T difference. Why
    > 52/42 instead of say 53/43 or 54/44?

    Or 50/40/30 which has a nice round numerology. But we shouldn't question these things. Shimano knows
    what's best for us, right?

    Art Harris
     
  7. > Or 50/40/30 which has a nice round numerology. But we shouldn't question these things. Shimano
    > knows what's best for us, right?

    Precisely. Just like Campy knows that, if we need a 29t rear cog, then we shouldn't be riding
    anything smaller than a 13t at the small end.

    --Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com
     
  8. Rick Onanian

    Rick Onanian Guest

    On Fri, 26 Dec 2003 17:24:12 GMT, "Mike Jacoubowsky"
    <[email protected]> wrote:
    >> Or 50/40/30 which has a nice round numerology. But we shouldn't question these things. Shimano
    >> knows what's best for us, right?
    >
    >Precisely. Just like Campy knows that, if we need a 29t rear cog, then we shouldn't be riding
    >anything smaller than a 13t at the small end.

    Well, don't forget, we're not allowed to have a wide range of available gears -- who would need
    that, anyway? I mean, maybe if there was such a thing as a "hill", but have you ever heard of one on
    THIS planet?

    Really, the triple's largest is a 52 while the double's is a 53...it makes no sense whatsoever. The
    42 triple middle vs. the 39 double small I can understand...

    >--Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com
    --
    Rick Onanian
     
  9. Tom Sherman

    Tom Sherman Guest

    Rick Onanian wrote:
    >
    > Well, don't forget, we're not allowed to have a wide range of available gears -- who would need
    > that, anyway? I mean, maybe if there was such a thing as a "hill", but have you ever heard of one
    > on THIS planet?

    If you can not climb any paved road with a 39/27, you are apparently not enough of a real cyclist to
    deserve consideration. [1]

    It does not make sense that most recreational road cyclists are riding with the same gearing as the
    UCI professionals.

    [1] My low gear is 47% of the gear inches provided by a 39/27 with a 23-622 drivewheel.

    Tom Sherman - Close to 41½ N, 90½ W
     
  10. Dianne_1234

    Dianne_1234 Guest

    On Thu, 25 Dec 2003 18:37:50 GMT, "Mike Jacoubowsky"
    <[email protected]> wrote:

    >> 1) Does anyone know why Shimano puts different rings on road triples than
    >on
    >> road doubles? Doubles seem to come with 53/39 combos, while triples come with 52/42/30. This
    >> seems odd to me; why not just add a third ring and
    >leave
    >> the other two the same? Is it a silly marketing thing, or is there a good technical reason
    >> for this?
    >
    >The most difficult front shift of all is moving from the middle chainring (on a triple) down to the
    >smallest.

    And the second-most difficult shift is from the smallest back up to the middle.

    Think of the chain angle accross the rings during this shift. The front derailleur pushes it into an
    angle from the small chainring towards the larger rings. The smaller the middle chainring, the more
    likely it is the chain will touch the big ring first and miss the middle entirely.
     
  11. Carl Fogel

    Carl Fogel Guest

    "Mike Jacoubowsky" <[email protected]> wrote in message news:<[email protected]>...
    > > Or 50/40/30 which has a nice round numerology. But we shouldn't question these things. Shimano
    > > knows what's best for us, right?
    >
    > Precisely. Just like Campy knows that, if we need a 29t rear cog, then we shouldn't be riding
    > anything smaller than a 13t at the small end.
    >
    > --Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com

    Dear Arthur and Mike,

    Come, come, fellows, let's not squabble about a few teeth during the holidays!

    As a friend often remarked at the Honda shop, it's easy enough to grind off a gear tooth or two--
    surely that will fix things, won't it?

    Carl Fogel
     
  12. Werehatrack

    Werehatrack Guest

    On Fri, 26 Dec 2003 17:02:57 -0600, Tom Sherman
    <[email protected]> may have said:

    >If you can not climb any paved road with a 39/27, you are apparently not enough of a real cyclist
    >to deserve consideration. [1]

    Or at least some of the Powers That Be seem to believe so. I think they all must live in someplace
    like Miami, where the only way to find a 300-foot elevation climb would be by riding up the fire
    escape stairwell of an office building that had one with a handicapped ramp. (As if you'll find
    one!) (100 feet can be had in a few parking garages, if you don't get arrested for trespassing.)

    (Of course, I shouldn't say too much; I'm in Houston, and just 75 feet above sea level...)

    >It does not make sense that most recreational road cyclists are riding with the same gearing as the
    >UCI professionals.

    But...but...if they had lesser gears than their idols, how would they ever be able to think they
    could achieve the same feats?

    (The dodge, of course, is to buy a touring bike; selected carefully, it has all the looks of a road
    bike, but with a 75% greater gear range...or more.)

    >[1] My low gear is 47% of the gear inches provided by a 39/27 with a 23-622 drivewheel.

    Would that be a 24/34 bailout combo on an mtb?

    I ended up with that combo on a bike last week for a couple of days; I was swapping wheels around to
    optimize a couple of things on other units, and a 14-34 cassette ended up on the bike with the
    24/34/44 triple. I think I could probably have pulled a loaded tandem up a grade with it. Not very
    *fast*, but the effect of the mechanical advantage was immediately evident.

    --
    My email address is antispammed; pull WEEDS if replying via e-mail.
    Yes, I have a killfile. If I don't respond to something,
    it's also possible that I'm busy.
    Words processed in a facility that contains nuts.
     
  13. Tom Sherman

    Tom Sherman Guest

    Werehatrack wrote:
    >
    > >[1] My low gear is 47% of the gear inches provided by a 39/27 with a 23-622 drivewheel.
    >
    > Would that be a 24/34 bailout combo on an mtb?
    >
    > I ended up with that combo on a bike last week for a couple of days; I was swapping wheels around
    > to optimize a couple of things on other units, and a 14-34 cassette ended up on the bike with the
    > 24/34/44 triple. I think I could probably have pulled a loaded tandem up a grade with it. Not very
    > *fast*, but the effect of the mechanical advantage was immediately evident.

    The low on my MTB is 22/32, at which point I am either having the front wheel come up in the air
    shortly before I fall over; or my rear wheel is spinning shortly before I lose all forward speed and
    fall over. But then I am lousy at riding off-road - but someone has to keep the manufacturers of first-
    aid supplies in business.

    My low road gear is a 22T granny (Deore LX crank), a 13/20 jackshaft step-up (QBP and Dura Ace track
    cogs) [1], and a 34T cog (XT Megarange cassette) on a wheel with a 47-406 tire. Why be simple when
    you can have it complicated (or as Mr. Fogel would put it, ride a contraption)? This low gear proves
    very useful on the back roads in the "driftless" area of SW Wisconsin, or on the bluffs of the
    Mississippi River where many of the grades are considerably steeper than 10%.

    [1] <http://www.ihpva.org/incoming/2002/sunset/Sunset005.jpg>

    Tom Sherman - Close to 41½ N, 90½ W
     
  14. > >The most difficult front shift of all is moving from the middle chainring (on a triple) down to
    > >the smallest.
    >
    > And the second-most difficult shift is from the smallest back up to the middle.
    >
    > Think of the chain angle accross the rings during this shift. The front derailleur pushes it into
    > an angle from the small chainring towards the larger rings. The smaller the middle chainring, the
    > more likely it is the chain will touch the big ring first and miss the middle entirely.

    True enough, but at least, when it misses the middle on the way up (and goes to the largest), you
    can easily shift it from there back down to the middle. If you can't get it to shift from the middle
    to small, you're simply out-of-luck (and most likely at a time when you really need it!).

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

    "dianne_1234" <[email protected]> wrote in message
    news:[email protected]...
    > On Thu, 25 Dec 2003 18:37:50 GMT, "Mike Jacoubowsky" <[email protected]> wrote:
    >
    > >> 1) Does anyone know why Shimano puts different rings on road triples
    than
    > >on
    > >> road doubles? Doubles seem to come with 53/39 combos, while triples
    come
    > >> with 52/42/30. This seems odd to me; why not just add a third ring and
    > >leave
    > >> the other two the same? Is it a silly marketing thing, or is there a
    good
    > >> technical reason for this?
    > >
    > >The most difficult front shift of all is moving from the middle chainring (on a triple) down to
    > >the smallest.
    >
    > And the second-most difficult shift is from the smallest back up to the middle.
    >
    > Think of the chain angle accross the rings during this shift. The front derailleur pushes it into
    > an angle from the small chainring towards the larger rings. The smaller the middle chainring, the
    > more likely it is the chain will touch the big ring first and miss the middle entirely.
     
  15. > Dear Arthur and Mike,
    >
    > Come, come, fellows, let's not squabble about a few teeth during the holidays!
    >
    > As a friend often remarked at the Honda shop, it's easy enough to grind off a gear tooth or two--
    > surely that will fix things, won't it?
    >
    > Carl Fogel

    Carl: I don't know about you, but in my case, you're looking at a 47-year-old that enjoys riding impossibly-
    steep roads but... the 27t large cog on a Shimano double just isn't going to cut it too much longer.
    A triple is in my future but... if Shimano had a 29... I could put it off for at least another
    couple years, maybe more!

    I hate to reduce this thread to discussions of practicality, but if we're going to have 10 cogs back
    there, why keep the range as narrow as the 9-speed systems? It's d-u-m-b dumb! We're only slightly
    better than the 5-cog days, when my racing bike had a 13-24. When we went to 6 cogs I was able to go
    wild and have a 26 for the steep stuff, which remained until the 9-speed systems gave me a 27. And
    now? Somehow I managed to survive with fewer than 9 cogs in the past... how come they want to keep
    cramming more cogs into the same range, instead of extending it out a bit?

    Heck, this would even help Division-1 racers on climbs like the Angrilu, where Heras used a triple
    to good effect. Had a 29t option been available, that might well have been used instead, saving a
    bit of weight.

    Sigh. Perhaps one more trip up Sonora Pass on a double, maybe...

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

    "Carl Fogel" <[email protected]> wrote in message
    news:[email protected]...
    > "Mike Jacoubowsky" <[email protected]> wrote in message
    news:<[email protected]>...
    > > > Or 50/40/30 which has a nice round numerology. But we shouldn't
    question
    > > > these things. Shimano knows what's best for us, right?
    > >
    > > Precisely. Just like Campy knows that, if we need a 29t rear cog, then
    we
    > > shouldn't be riding anything smaller than a 13t at the small end.
    > >
    > > --Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com
    >
    > Dear Arthur and Mike,
    >
    > Come, come, fellows, let's not squabble about a few teeth during the holidays!
    >
    > As a friend often remarked at the Honda shop, it's easy enough to grind off a gear tooth or two--
    > surely that will fix things, won't it?
    >
    > Carl Fogel
     
  16. Tom Sherman

    Tom Sherman Guest

    Mike Jacoubowsky wrote:
    > ... Carl: I don't know about you, but in my case, you're looking at a 47-year-old that enjoys
    > riding impossibly-steep roads but... the 27t large cog on a Shimano double just isn't going to cut
    > it too much longer. A triple is in my future but... if Shimano had a 29... I could put it off for
    > at least another couple years, maybe more!...

    I know this suggestion will horrify some people (What a Fred!), but why not put a Shimano MTB
    derailleur and cassette on the back and have a 32T cog for the hills? Or is this not STI compatible?
    (It works fine with Shimano bar-end shifters.)

    Tom Sherman - Close to 41½ N, 90½ W
     
  17. "Tom Sherman" wrote:
    > I know this suggestion will horrify some people (What a Fred!), but why not put a Shimano MTB
    > derailleur and cassette on the back and have a 32T cog for the hills? Or is this not STI
    > compatible? (It works fine with Shimano bar-end shifters.)

    I just upgraded my wife's road bike with an 11-32 (9-sp) cassette and a Deore LX rear der. Works
    fine with STI.

    Art Harris
     
  18. Carl Fogel

    Carl Fogel Guest

    "Mike Jacoubowsky" <[email protected]> wrote in message news:<[email protected]>...

    [snip Carl]

    > Carl: I don't know about you, but in my case, you're looking at a 47-year-old that enjoys riding
    > impossibly-steep roads but... the 27t large cog on a Shimano double just isn't going to cut it too
    > much longer. A triple is in my future but... if Shimano had a 29... I could put it off for at
    > least another couple years, maybe more!
    >
    > I hate to reduce this thread to discussions of practicality, but if we're going to have 10 cogs
    > back there, why keep the range as narrow as the 9-speed systems? It's d-u-m-b dumb! We're only
    > slightly better than the 5-cog days, when my racing bike had a 13-24. When we went to 6 cogs I was
    > able to go wild and have a 26 for the steep stuff, which remained until the 9-speed systems gave
    > me a 27. And now? Somehow I managed to survive with fewer than 9 cogs in the past... how come they
    > want to keep cramming more cogs into the same range, instead of extending it out a bit?
    >
    > Heck, this would even help Division-1 racers on climbs like the Angrilu, where Heras used a triple
    > to good effect. Had a 29t option been available, that might well have been used instead, saving a
    > bit of weight.
    >
    > Sigh. Perhaps one more trip up Sonora Pass on a double, maybe...
    >
    > --Mike-- Chain Reaction Bicycles

    [snip]

    Dear Mike,

    While we both agree that everyone of any importance is currently 47, I'm baffled by your outlandish
    claims of bicycles that sport more than 7 rear cogs. I just counted mine and confirmed that there
    are only seven. More would be ostentatious.

    As for the front, where would you put a third chain ring? I looked again, just to be sure, and
    am positive that there is no place to mount such a thing. In any case, Shakespeare warned us
    against them:

    "Triple-turn'd whore!"

    -- Antony & Cleopatra, IV, xiii

    Have you considered the more practical solution of mounting smaller wheels to gear down for hills? A
    650 rear wheel might help. A 650 would also be needed in the front to prevent the bike from sloping
    backward and going uphill even on level ground.

    I'm always glad to help bicycle dealers and engineers solve these knotty technical problems.

    See you at 48.

    Carl Fogel
     
  19. On Sat, 27 Dec 2003 07:43:06 +0000, Tom Sherman wrote:

    > I know this suggestion will horrify some people (What a Fred!), but why not put a Shimano MTB
    > derailleur and cassette on the back and have a 32T cog for the hills? Or is this not STI
    > compatible? (It works fine with Shimano bar-end shifters.)

    It will work fine. The only problem is using a mountain-bike front derailleur with STI.

    --

    David L. Johnson

    __o | A mathematician is a machine for turning coffee into theorems. _`\(,_ | -- Paul Erdos
    (_)/ (_) |
     
  20. > I know this suggestion will horrify some people (What a Fred!), but why not put a Shimano MTB
    > derailleur and cassette on the back and have a 32T cog for the hills? Or is this not STI
    > compatible? (It works fine with Shimano bar-end shifters.)

    Been there, done that, a couple years ago on Sonora Pass. May do it again, but I would really like
    just one gearing setup that I can use for everything, and the 12-32 setups space the gears a bit
    further apart than I like. Maybe when mountain bikes get 10-speed systems?

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