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Old 04-17-14, 09:04 AM   #1
Johnny Rebel
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Mind the gap?

Hey good folks. So I'm simplifying a half-step plus granny setup on my 80's 'sport touring' bike. Currently the front rings are 50/46/30 with a 5 speed 14-26 (I think) freewheel in the back. I'm leaning towards removing the 50 tooth chainring and going to 7 speeds with an 11-30 freewheel I found. I know the wheel will convert to 7 speeds easy enough.The idea would be to stay in the 46 ring most of the time, and yes I'm a slow fat tourer.

My question: is that jump between 15 and 18 (14.7 gear inches to be precise) going to be a pain in the butt gap (68 to 82 jump) or am I overthinking this? The top end and low end of this setup should be swell for me. Thanks for your thoughts!
Here is the proposed gearing chart:

46 30
11 111.9 73.0
18.2 %
13 94.7 61.8
15.4 %
15 82.1 53.5
20.0 %
18 68.4 44.6
16.7 %
21 58.6 38.2
14.3 %
24 51.3 33.5
25.0 %
30 41.0 26.8
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Old 04-17-14, 09:16 AM   #2
fietsbob 
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Touring, triple, bar end friction shifting. the 16t jump from a 24 to a 40t , even with out the newer ramped and pinned shifting features

when I upshift , I do that at the crest of the hill, where I am able to remove the strain on the chain, when climbing ,
then the rise up to the middle chainring goes well , in a reasonable time period,... though not like an electric switch ..


though the gear change of the internal gear in my Schlumpf * Mountain Drive crank is significantly quicker , the chain is not shifted ,
the internal reduction gear is engaged , then a 50t then acts like its a 20t. as the crank turns faster than the chainring .

*the companies over drive, speed drive, version is a 1.6x , so a 34t acts like a 54t,then, chainring turns faster than crank arms .

Last edited by fietsbob; 04-17-14 at 09:22 AM.
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Old 04-17-14, 09:27 AM   #3
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And Velo Orange is big on the 46/30 doubles , inquire there as to which of their several models would be fastest shifting , if that is your criteria.
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Old 04-17-14, 09:58 AM   #4
Drew Eckhardt
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Quote:
Originally Posted by Johnny Rebel View Post
My question: is that jump between 15 and 18 (14.7 gear inches to be precise) going to be a pain in the butt gap (68 to 82 jump) or am I overthinking this? The top end and low end of this setup should be swell for me. Thanks for your thoughts!
I don't use gearing which has any 2 tooth jumps up to the 19 cog, and most other road cyclists seem to eschew such big gaps through the 17 cog. To do that I ran 50-40-30 x 13-14-15-16-17-18-19-21 in the 8 cog era, providing a straight block for plains rides but low like 42x28 for mountains. When Camapagnolo discontinued 13-21 I upgraded to 9 cogs instead of living with 13-23 8 cogs.

Obviously your tastes may vary and you're in a better position to know what suits them than the rest of us.

Last edited by Drew Eckhardt; 04-17-14 at 10:10 AM.
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Old 04-17-14, 10:23 AM   #5
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I also find two tooth gaps in the smaller cogs unpleasant. My current setups are 50/39/26 triple cranks and 12x27 or 13x29 10-speed cassettes. As you've discovered fewer cogs and wider overall ranges leave BIG holes in the middle.
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Old 04-17-14, 01:41 PM   #6
Mr IGH
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Quote:
Originally Posted by Johnny Rebel View Post
...My question: is that jump between 15 and 18 (14.7 gear inches to be precise) going to be a pain in the butt gap (68 to 82 jump) or am I overthinking this?...
Here's how i approach the issue:
I prefer a cadence between 85~100rpm, that's a 15% range. If the gear change is larger, I have to change my speed to accommodate my cadence preference. If I shift up and the step is greater than 15%, then I have to increase my speed to be comfortable. This isn't that big of a deal when riding alone but it is when riding with another person or a group.

Another issue is where you have that big step. You have it in the "sweet spot" of 70 inches. Most of my riding is done in gears from 50" to 80", having nice small steps in that range is nice, esp if you're riding in a group.

What's the big deal about keeping the triple and using the half step? It works well until the cassette hits 9 speed.
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