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Duracel
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PostPosted: Wed Jul 15, 2015 4:53 am Reply with quote Back to top

Nice comments everyone. Now hopefully the OP learned something out of all of this!

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envy
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PostPosted: Wed Jul 15, 2015 7:30 am Reply with quote Back to top

Doubt it
 
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thudd
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PostPosted: Wed Jul 15, 2015 8:32 am Reply with quote Back to top

"Well, it's one (faster), isn't it? It's not ten. You see, most blokes, you know, will be (riding) at ten. You're on ten here, all the way up, all the way up, all the way up, you're on ten on your (bike). Where can you go from there? Where?"

11!
 
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suvlako
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PostPosted: Wed Jul 15, 2015 10:48 pm Reply with quote Back to top

did you guys see the article on the "One Up" 45 tooth conversion on Pinkbike today. looks like it's even easier to get that "granny gear" ratio now...

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BikerDodd
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PostPosted: Thu Jul 16, 2015 12:41 am Reply with quote Back to top

I'm trying to find a thing I saw the other day on gear ratio's and whats to gain and whats to lose. They basically made charts for the most common gear set ups by dividing from ring teeth by cassette teeth. It was interesting. Considering Interlock Racing and Praxis now make 11-40 and 11-42 10 speed cassettes it's almost worth keeping the 10 speed (especially if your doing a 1x) if your bike is already set up for a 10x. The actual gear ratio's don't vary that much compared to an 11 speed and you still get the range, minus the 10T from sram. However, considering Sram and Shimano now have the consumer priced 11 speed set ups (Sram GX and Shimano XT M8000) it may be worth the upgrade, or bike build consideration. In all out versatility, comparing weight consciousness to gear ranges and price, the 2x10 with a 24/38 chainring paired with the 11-40 cassette was the best option on paper. Not many people would be strong enough to push the 42+ third chain ring and the 42/45 rear cog would nearly be overkill with the smaller front ring. It was a good read, if anyone can find it.

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Evil_Patrick
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PostPosted: Thu Jul 16, 2015 7:16 am Reply with quote Back to top

About 6 months ago, I created an Excel spreadsheet that is fully sortable and has all the 1-by, 2-by, and triple chain ring and rear cog combos, with custom chain ring sizes as well. It was really helpful to me, as it allowed me to dial in the middle to closely replicate the 3 by 9 ratios that I knew and loved. That made a big difference to me. I tried a different set up and found it just weird -- wrong cadence / speed for the tech sections.

The sheet has a "master sort" to show how all gear ratios compare to each other, and it's color coded to make these comparisons even easier.

If anyone wants a copy, PM me your email address and I'll send you the file.

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suvlako
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PostPosted: Thu Jul 16, 2015 7:23 am Reply with quote Back to top

Does it account for wheel size and crank arm length? Most people forget that these are just as important to the equation as front and rear set up. Just sayin.

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BikerDodd
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PostPosted: Thu Jul 16, 2015 10:26 am Reply with quote Back to top

Gear ratios are just to calculate distance traveled. So if you have a 32 front and a 42 rear the ratio is about .76. So for every 1 full turn of the crack (100% revolution) the wheel will travel 76% of 1 full turn. To simplify it a 32 front against 32 rear is a 1:1 ratio. Take the wheel/tire diameter and multiply that by 3.14 (Pi). In Inches a 26" wheel will travel 81.64" with a 1:1 ratio and a 29 will travel 91.06". The leverage then does depend on rider weight and crank length. Obviously a longer crank will give more overall pedaling leverage but it really depends on the gear ratio and how far the wheel will travel. To make it nearly equal, assuming a 170mm crank and 160# rider, if you have a 1x set up you would want a 34t on a 26", 32t on a 27.5" and a 30t on a 29" to have about the same Mechanical Advantage. With those front chainrings and a 42 cog on the back a 26" wheel will travel 65.312", 27.5" is 65.625" and a 29" is 64.654". So in all of this the bigger the wheel, the smaller the gear ratio that's needed to achieve the same leverage, or pedal, rate given a set amount of force.

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DeepVI
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PostPosted: Thu Jul 16, 2015 10:37 am Reply with quote Back to top

Math! Quit being all science-y college boy!

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Evil_Patrick
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PostPosted: Thu Jul 16, 2015 12:21 pm Reply with quote Back to top

suvlako wrote:
Does it account for wheel size and crank arm length? Most people forget that these are just as important to the equation as front and rear set up. Just sayin.


Though they are important, neither changes the gear ratios.

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twowheelsdown2002
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PostPosted: Thu Jul 16, 2015 10:15 pm Reply with quote Back to top

Here is another really good calculator that lets you see visually how every gear compares to each other, rather than just number ratios. It has all the latest 10 and 11 speed cassettes. It also allows you to put 2 setups directly side by side, so you can see where the gaps are, and how each setup is spread out. You can also select "speed" on the display chart, and move the cadence selector up or down, and it will show you how fast you will be going in each gear. http://www.gear-calculator.com/
 
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twowheelsdown2002
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PostPosted: Sat Jul 18, 2015 12:28 pm Reply with quote Back to top

Here is a screenshot using the HTML5 gear calculator. I think it is one of the best gear selection tools out there for helping you choose what is right for you, and your riding conditions. You can see exactly what various changes will do, and where you will have to make compromises. Give it a shot, I think you will find it a very useful tool.

I used a 27.5 vs 29 on this chart with 3x9 vs 11 speed for comparison. As you can see, I really only lost 2 gears on top, while having a super low climbing gear. I rarely am in situations that I am spinning along at 30mph or more. And if you tweak the speed dial, I am doing 27mph at 120rpm, which is a cadence I have no problem spinning for a reasonable duration. That is a pretty good speed even on the road, let alone a trail. So for my uses, I am willing to sacrifice those speed gears, to lose over a pound of weight, have excellent chain retention, a super silent ride even in bumps, and no double shift/crossgear concerns. One button up and down. Works for me.
https://www.dropbox.com/s/0ioa195fni9krfd/Screenshot%202015-07-18%2012.15.10.png?dl=0
 
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twowheelsdown2002
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PostPosted: Sat Jul 18, 2015 12:37 pm Reply with quote Back to top

 
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bigworm
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PostPosted: Tue Jul 21, 2015 1:00 pm Reply with quote Back to top

My fatbike has a 1x10.

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DeepVI
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PostPosted: Tue Jul 21, 2015 4:03 pm Reply with quote Back to top

Your face is 1x!

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