Gearing question

[PATRICK MOORE]

In a frantic attempt to make the perfectly accessible into something
more complicated, I ask whether the 2X9 gearing below I propose for my
(very Rivish in philosophy if not Rivendellianly lugged) has any
drawbacks compared to the current 3X7 setup.

Current:

(Big Apple wheelset, 29" diameter.)
46 36 24
16 83 65
18 74 58
20 67 52
23 58 45 30
26 51 40 27
30 44 35 23
34 31 20

Proposed:

36 24
12 87 58
13 80 54
14 75 50
16 65 33
18 58 33
21 50 33
24 44 29
28 37 25
34 31 20

Thanks.

--
Patrick Moore
Albuquerque, NM
For professional resumes, contact
Patrick Moore, ACRW
http://resumespecialties.com/index.html

[PATRICK MOORE]

I meant to add that in either I have the cruising gears (mid '60s for
pavement, low 60 or upper 50s for dirt) in the middle of the big ring.

[Joe Broach]

Looks good to me! I tried something similar for a while with a 34/22.
Front derailer setup was fiddly. There was a fine line between getting
it to shift to the "big" ring and shifting off to the outside of the
big ring. I ended up switching to manual front shifting, then removed
the rear derailer to make a sweet 2x3 setup (3 usable gears).

Best,
joe broach
portland, or

[robert zeidler]

Got a lotta 33's. 

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[William]

24x16, 24x18, and 24x21 are not all 33 inch gears.  Other than the math errors made by your personal assistant, I approve.  2x9 is the way to go for almost everybody, in my opinion.  

[Brian Campbell]

If you you go 2x11, then it will go to 11.....

[dougP]

Patrick:

I dunno if you've achieved your goal "...to make the perfectly
accessible into something
more complicated,...".

One has 12 different gears and the other 11; doesn't seem too
meaningful a difference, as long as you've got the range you want.
Assuming you'll use the same 36T & 24T rings, and that they shift OK
now, seems like a simplification if anything. Your proposed 9 speed
looks nicely progressive.

Heck, just stick on the 9 speed and ride it for a while before
bothering messing with the crankset. A couple of turns of the FD
adjustment screw & you've got a double.

dougP

[Steve Palincsar]

On Thu, 2012-03-29 at 08:39 -0600, PATRICK MOORE wrote:
> In a frantic attempt to make the perfectly accessible into something
> more complicated, I ask whether the 2X9 gearing below I propose for my
> (very Rivish in philosophy if not Rivendellianly lugged) has any
> drawbacks compared to the current 3X7 setup.

1. Chain, chain ring and sprocket life is going to be less.

2. You are never going to use that 24 with anything smaller than a 21T
sprocket, so you might as well plot the chart reflecting how you're
going to use it, the way you did with the triple. It will make the true
shifting pattern more obvious; the current chart obfuscates it, and
makes it seem as though you're going to be using the two rings equally
when in reality you will be using it as a 1x9 + granny.

[PATRICK MOORE]

Thanks for the commentary. I like the fact that the 36 will handle
9/10 of the work with the 24 just as an occasional bailout.

Do those of you who use such small rings find that the rings, cogs and
chain wear much more quickly?

Now I need to pick up some cogsets for disassembly and re-arrangement.

[dougP]

Patrick:

Since you'll be spending most of your time on a single ring, how about
one of Surly's steel ones? Also, you can probably mix'n'match 7/8/9
speed cogs with 9 speed spacers to optimize using thicker cogs for the
ones you use most & 9 speed (thinner) for the extremes. Currently I'm
using a 13-28 7 speed cassette with a 34t 9 speed big cog, all spaced
with 8 speed spacers, on an 8 speed freehub. Shifts great & even
indexes correctly. Using Ultegra 8 speed bar ends & one of the
Microshift RDs that Riv had on sale a while back. Nothing exotic.

dougP

[Michael Hechmer]

I think the new set up actually looks like this:

		36	24
12		87	58
13		80	54
14		75	50

16		65	44
18		58	39
20		52	35
23		45	30
26		40	27
30		35	23
34		31	20

I would find a hi gear of 87 too low and a  low gear  below 25 unnecessary, but to each his own.  Other than the big jump between the 14 & 16 on the big ring the shifting pattern is remarkably  good for a 12 tooth difference and a wide range cassette.  This gearing question has no perfect answer, just a bunch of trade offs between wide range and acceptable patterns.  If it suits you, go for it .  Quite creative.

I ride a 44/30 with an 11-28 nine speed cassette and lots of people would find that.... unusual.

Michael

[PATRICK MOORE]

That's a good idea. I'll probably mix and match anyway to use the cogs
I have, many of which are 7 speed. Right now the cassettes (BAs and
Kojaks) are mostly 7 speed cogs with some 9 speeds, one or two Miche
aftermarkets and mostly 9 sp spacers with two extra spacers between
the big cogs and the freehub flange.

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[PATRICK MOORE]

Thanks, you are right. Yes, I did a "replace all" for tire diameter and forgot about the cogs. 

This wheelset is geared for dirt, so the high and low are useful. Anyway, riding fixed so much, I find myself "not bothering" much above 85": I can sprint such a gear to well over 30 at need, but usually just coast. And I find a gear of about 30" ample for most pavement hills, but grinding through sand takes as low as you've got.

I will probably play around with these ratios; the 65 is fine for pavement or firm dirt with the Big Apples but a 61" (17t) instead of the 58/18 would work better for looser dirt cruising. 

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[PATRICK MOORE]

I went to a bike swap this morning and scored 3 HG cassettes (two missing outer cogs and lockrings) for $5 -- not bad. Brother willing to trade stock aluminum 36 and 24 for steel ones. Ready to go!