P
Pinnah
Guest
[email protected] (Russell Seaton) wrote:
>I've run the numbers on my spreadsheet using my existing
>14-16-18-21-24-28-34 7 speed cassette and a 42-39 did not
>work well. 42-40 worked better. The best chainring setup
>I've found with the above 7 speed setup is the 48-45 half
>step. The 42-40 setup just did not produce enough jump
>between successive gears. Your 12-28 7 speed cassette is
>the same as the above cassette except you have a 12 instead
>of a 34 or 32.
Couple of things, including a retraction/correction.
1) I was able to dig out the specs from my old set up. It
was (to my astonishment) a 50/46/24, very close to your
preferred 48/45. I musta had young legs once. Note: I
used it with a 13-32 6-speed cassette.
2) I'm not seeing the pit falls of the 42/39 yet, other than
the really low gearing. My casual review of the gear
charts (generated from Sheldon's very cool site) suggest
that any 3 tooth jump on the chain rings gets you really
close with most off the shelf cassettes. More important I
would think, is whether or not the general size of the
chain rings is getting the basic range of gears desired.
I think your 48/45 is probably better in this regard.
3) I'm still getting my head around your desire for running
a 24t chain ring with 24 - 18 cogs. My gear charts
(again, taken from Sheldon's site) indicate this is in
the gear inch range of 26 to 39 inches or so. It looks
to me that this run of gears is available with a 36t
chain ring on 34 - 28t cogs. If you want something close
to a steady set of step (full, half or what have you)
from a 20 inch gear up to 100 inch gear, perhaps a more
standard alpine gearing would work for you like a
48/36/24. I just think you really beg problems as soon
as your rear cogs get to be the same size as your granny
or smaller.
>Harris Cyclery carries 110mm bcd chainrings in every size.
>Including 41 and 45 teeth. Both T.A. brand, expensive, and
>a cheap BMX brand.
Excellent. Thanks.
-- Dave
==============================================
"It is impossible, or not easy, to do noble acts without
the proper equipment." Aristotle, <<Politics>>, 1323a-b,
trans Jowett
==============================================
>I've run the numbers on my spreadsheet using my existing
>14-16-18-21-24-28-34 7 speed cassette and a 42-39 did not
>work well. 42-40 worked better. The best chainring setup
>I've found with the above 7 speed setup is the 48-45 half
>step. The 42-40 setup just did not produce enough jump
>between successive gears. Your 12-28 7 speed cassette is
>the same as the above cassette except you have a 12 instead
>of a 34 or 32.
Couple of things, including a retraction/correction.
1) I was able to dig out the specs from my old set up. It
was (to my astonishment) a 50/46/24, very close to your
preferred 48/45. I musta had young legs once. Note: I
used it with a 13-32 6-speed cassette.
2) I'm not seeing the pit falls of the 42/39 yet, other than
the really low gearing. My casual review of the gear
charts (generated from Sheldon's very cool site) suggest
that any 3 tooth jump on the chain rings gets you really
close with most off the shelf cassettes. More important I
would think, is whether or not the general size of the
chain rings is getting the basic range of gears desired.
I think your 48/45 is probably better in this regard.
3) I'm still getting my head around your desire for running
a 24t chain ring with 24 - 18 cogs. My gear charts
(again, taken from Sheldon's site) indicate this is in
the gear inch range of 26 to 39 inches or so. It looks
to me that this run of gears is available with a 36t
chain ring on 34 - 28t cogs. If you want something close
to a steady set of step (full, half or what have you)
from a 20 inch gear up to 100 inch gear, perhaps a more
standard alpine gearing would work for you like a
48/36/24. I just think you really beg problems as soon
as your rear cogs get to be the same size as your granny
or smaller.
>Harris Cyclery carries 110mm bcd chainrings in every size.
>Including 41 and 45 teeth. Both T.A. brand, expensive, and
>a cheap BMX brand.
Excellent. Thanks.
-- Dave
==============================================
"It is impossible, or not easy, to do noble acts without
the proper equipment." Aristotle, <<Politics>>, 1323a-b,
trans Jowett
==============================================