Shimano "A" and "B" chainrings?
Sheldon Brown
>
> Hi all,
>
> A question about Shimano Ultegra chainrings. I currently have a 53"B"
> large ring and a 39 inner ring. I want to change the 39 to a 42. I'm
> told that I must replace both the outer and inner rings because I have a
> "B" 53 ring and it's incompatable with the 42 inner ring. As I
> understand it, the 53"A" large ring must only be used with the 42 inner
> ring, and the 53"B" ring must only be used with the 39 inner ring.
>
> I have spoken to several bike shops about the importance of sticking to
> this "A" = 42, "B" = 39 concept, and I get reactions from, giving me a
> strange look and tell me it doesn't make any difference, or that they
> never heard of such a thing. Other people, mostly knowledgable riders,
> say that if I want to retain great shifting, I should follow these
> guidelines.
Until a few years ago, there was no such thing as matched chainrings,
and it wasn't a problem. When Shimano introduced their "Superglide"
chainrings, they were matched, and this does, indeed, provide slightly
smoother shifting. It is, however, far from a necessity. My advice is,
if you're bound and determined to go to a 42, just put on the 42 and try
it.
If you find the shifting satisfactory, you've saved the price of a
chainring you didn't need.
If you find the shifting less than satisfactory, you can always buy a
new 53.
If it were me, and I found the 39 x (whatever) too low for the terrain,
I'd look into a tighter rear cluster (unless you've already got a
corncob) instead.
Sheldon "Is 42 Really The Answer?" Brown
Newtonville, Massachusetts
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Tom Banaszak
A question about Shimano Ultegra chainrings. I currently have a 53"B"
large ring and a 39 inner ring. I want to change the 39 to a 42. I'm
told that I must replace both the outer and inner rings because I have a
"B" 53 ring and it's incompatable with the 42 inner ring. As I
understand it, the 53"A" large ring must only be used with the 42 inner
ring, and the 53"B" ring must only be used with the 39 inner ring.
I have spoken to several bike shops about the importance of sticking to
this "A" = 42, "B" = 39 concept, and I get reactions from, giving me a
strange look and tell me it doesn't make any difference, or that they
never heard of such a thing. Other people, mostly knowledgable riders,
say that if I want to retain great shifting, I should follow these
guidelines.
I would really appreciate any opinions offered by the knowledgable folks
in rbt. Thanks in advance for your help
Tom
Qui si parla Campagnolo
large ring and a 39 inner ring. I want to change the 39 to a 42. I'm
told that I must replace both the outer and inner rings because I have a
"B" 53 ring and it's incompatable with the 42 inner ring. >>
What utter crappola-just change the small ring-
Remember, in a time long, long ago-big rings didn't have all the doo-dads to
shift under a bit of load-
Use a little finesse in all shifts, up and down the rings
And install the 42 tooth ring
Peter-
Peter Headland
the small ring and the hooks on the inside of the large ring. These have to
line up properly to get a smooth change. Depending on the extent of the "A"
vs. "B" differences, your shifts onto the big ring might be poor with
non-matched rings because the chain will miss the hooks as it rides off the
smaller ring. Going from 39t to 42t seems like it would be less of a problem
than the other way around. Why not try it and see how it is? You can always
change the big ring later if needs be.
--
Peter Headland, Matrix Link, UK
Pe...@matrixlink.com
http://www.matrixlink.com/
Mike Pomrink
In fact, I can't notice any difference in shifting between the two setups
(the other being a 53"B" and a 39"B).
Mike Pomrink
Tom Banaszak <ped...@tampabay.rr.com> wrote in article
<pedaler-3680EE.19394029111999@news-server>...
> Hi all,
>
> A question about Shimano Ultegra chainrings. I currently have a 53"B"
> large ring and a 39 inner ring. I want to change the 39 to a 42. I'm
> told that I must replace both the outer and inner rings because I have a
Mike Jacoubowsky
difference at all. With STI, you will notice some deterioration in
shifting, but my main concern is the increased possibility of shifting off
the inside of the front chainring when downshifting. If this does occur,
you can always get a 3rd-eye chainwatcher, which will eliminate this
problem.
--Mike-- Chain Reaction Bicycles
http://www.ChainReactionBicycles.com
"Tom Banaszak" <ped...@tampabay.rr.com> wrote in message
news:pedaler-3680EE.19394029111999@news-server...