I've run HS+G for about 40 years after reading an article by Frank Berto(?)
in Bicycling. I still strongly prefer HS+G over any other gearing - a very
wide range with little duplication.
* When shifting between the large & middle rings I have ratios like a
straight block racing cassette (yet without the duplication of a typical
compact double);
* I can make whole step changes when accelerating or for more rapid changes
in slope or wind;
* Yet can reach down to very low gears on steep hills (or completely
bonked);
* Of the 27 available combinations, at least 20 can be used without
duplications;
* An additional 4 combos are available on the small ring if I don't want to
shift to the middle, giving 24 usable gears out of the 27. (I avoid
cross-chaining).
I started with 5-spd Regina freewheel, then 6-spd SunTour Ultra, now an
off-the-shelf Shimano 9-spd cassette. When I built my AHH Grant seemed to
think I was nuts, but accommodated my wishes anyway, installing a 41-tooth
TA middle ring in place of the standard 36.
I think of the HS+G as a wide range double with the ability to "fine-tune"
my cadence on the top end. I probably ride 75% on the middle (41)
chain-ring, 15% small (24) on hills & 10% on the large (44) on gently
rolling flats (to keep my cadence comfortable, and, yeah, the small
differences make a difference). I don't shift between the large rings as
much as Steve suggests, but the versatility is exceptional!
Here is my gear chart with shifting through the 20 practical available
combinations. The whole steps average about 15%, with 1/2 steps around
7%. I generally start in the 41x28 gear, shifting whole steps for most
use, especially when accelerating from a stop. I use the 1/2 steps to fine
tune my cadence with minor changes in slope or wind. On hills I drop to
the 24 chain-ring. On hills I'm going to want whole steps anyway as slopes
change often. On the 24 I often shift as far as the 16 in the rear if I
think a more gentle slope may not last, rather than doing the double shift
from the 24x24 to the 41x36 across 3 cogs in the back (which you'll do
anyway on a compact double). Yeah, these are "duplicates" but it's
sometimes more convenient to stay on the small.
----+------------------------- Cassette cog tooth count
------------------------+
| 12 14 16 18 21 24 28 32
36 |
----+---------------------------------------------------------------------------+
44 | 94.4-(17)-80.9 70.8 62.9 53.9 47.2 40.5 35.4
31.5 |
| \ / \ / \ / \ / \ / \ /
\ |
| (7) (6) (7) (5) (7) (9) (7) (6) (7) (9) (7) (6)
(7) |
| \/ \/ \/ \/ \/ \/
\ |
41 | 88.0 75.4 66.0 58.6 50.3 44.0 37.7
33.0-(13)-29.3 |
|
________(14)_________/ |
|
/ |
24 | 51.5 44.1 38.6 34.3 29.4
25.7<-->22.1<-->19.3<---->17.2 |
| (17) (14) (13) (17) (14) (17) (14)
(13) |
----+---------------------------------------------------------------------------+
(x): percent change between gears
On Thursday, June 2, 2016 at 9:30:19 PM UTC-7, Lungimsam wrote:
>
> So, I think this would work (although the Sheldon calculator has no 584
> wheel size, I used 27" nominal as option):
>
> 24/40 with an (11-13-15-18-21-24-28-34) 8-speed cassette would give me the
> ratios I need. That is like all the ratios of my current middle and outer
> rings combined with similar jumps between cogs.
>
> I could not get wide enough ratios with a 7-speed without huge cog jumps,
> so looks like I would have to use an 8-speed, but allowing good friction
> shifting still.
>
> But that would give me the ratios I need in one big ring, with the 24 as
> the bail out. Though the 6 cog jump to the largest cog looks like it might,
> in practice be too much.
>
> Maybe I just need to stick with the triple. Too much thinking.
>
>
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