# gear ratios?



## NukeDOC (Nov 11, 2011)

here in san diego, there are a lot of hills. usually nothing steeper than 15% grade. a lot of 10-12% though. i usually ride my road bike, but i like to commute with my single speed. 

currently im running a 48x17T gear ratio. i actually upped it from a 46x17T ratio because it wasnt fast enough haha. but now i am feeling the effects of the hills in my commute. 46x17 was ok, but i still would like to be able to climb a little better yet still have the ability to at least cruise at 18mph at least.

what size chainring would you recommend? i was thinking 44, but dont want to find out that im still killing myself taking the hills.


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## bayAreaDude (Apr 13, 2012)

Seems like a fixie just isn't the right tool for the job.


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## NukeDOC (Nov 11, 2011)

no fixie for me. only single speed. i need to coast haha. but yeah i agree, but cant justify a 3 mile commute to work on my full carbon roadie.

my commute home is about 360ft of gains, which are mostly just slight grade false flats. the last 65ft is what gets me at 12% grade. more of a speed bump but definitely rough with my current gear ratio. haha.

i wonder if there is a computer that tells you how fast your cadence will be at certain speeds, depending on gear ratio. i think something like that would definitely put me in the right direction.


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## NukeDOC (Nov 11, 2011)

ok i did some calculations. please correct me if i am wrong. 
given:
circumference of 700x23 tire is about 210cm
there are 160934cm in 1mile
thus approx 766 tire revolutions in 1mile

so:
a speed of 18mph would have 13788 tire revolutions per hour
thus about 230 tire rpms.
with a 44x17 gear ratio at 2.58:1 i would have a cadence of just about 90. 

so i guess i just gotta try it and see if i can get enough power from this ratio to get me up the hill now huh?


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## Schneiderguy (Jan 9, 2005)

Check out the Speed Calculator on the Wabi Cycling site. You can plug in various gearing as well as cadence.


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## Dave Hickey (Jan 27, 2002)

If you have a smart phone, there are a few gear calculator apps

I'm using one called "bicycle gears"

you've gone from 71 gear inches to 74 gear inches..

I run between 65 and 70 gear inches on my fixies/SS... At 70 gear inches, I have no problem running at 18mph..

Without knowing your fitness level it's hard to say but IMHO, you are good at your current set up.( 46 x 17) . I'd ride it more before you change again...


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## PSC (Mar 10, 2004)

I run a 42/17, and have no problem doing 17.5-21.5 mph(90-110rpms) with sprints up to 28 mph. I live in Seattle/Tacoma and have no problems with the short steep climbs and find myself passing guys on highend bikes on climbs all the time. On a SS I find you have to attack climbs just to get up them, so there is no time to relax. On a geared bike you can downshift and ease up, on a SS you don't have that option.


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## Fixed (May 12, 2005)

*tallest*

Use the tallest gear you can and still get up the hills. To me, it's that simple, and I do a lot of long fixed gear rides in the mountains.

What is the actual effect of using your 48x17? Sore knees, aching tendons, or just tired? If it's just tired, suck it up and you'll get used to it. If it's a joint issue, back off on the gearing until you get more used to it or discover your joints just can't handle it.



NukeDOC said:


> here in san diego, there are a lot of hills. usually nothing steeper than 15% grade. a lot of 10-12% though. i usually ride my road bike, but i like to commute with my single speed.
> 
> currently im running a 48x17T gear ratio. i actually upped it from a 46x17T ratio because it wasnt fast enough haha. but now i am feeling the effects of the hills in my commute. 46x17 was ok, but i still would like to be able to climb a little better yet still have the ability to at least cruise at 18mph at least.
> 
> what size chainring would you recommend? i was thinking 44, but dont want to find out that im still killing myself taking the hills.


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## JCavilia (Sep 12, 2005)

Work on your spin. If you want to ride a ss in huilly terrain, and want to cruise at a good speed, you're going to have to spin a high cadence. 90 rpm to get you 18 mph with 44x17 should be easy. You should be able to learn to spin 100 or more with some practice.



> so i guess i just gotta try it and see if i can get enough power from this ratio to get me up the hill now huh?


Power doesn't come from a gear ratio; it comes from your muscles. The question is whether the power you can produce will give you sufficient speed on those climbs with that ratio to put you at a comfortable cadence.

How are you doing that steep climb? If you're trying to stay seated, a SS just isn't going to work well. You're going to be at a low cadence, and you should be standing.


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## jtompilot (Mar 31, 2002)

My new SS has a 44x16. In group rides up to 25mph isnt to bad. The down hill at 36mph trashed my legs after 10 seconds. I have only done short climbs up to 7% grade, not alot of fun but doable.

Spin baby spin.


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## NukeDOC (Nov 11, 2011)

thanks for all the replies guys. i am comfortable with spinning up as high as 110 over about 5-10 continuous. so i think i will be good with 44x16. i am not sitting as i climb smaller steeper hills. im definitely out of the saddle. its just that with my current 48x17 i find myself snaking (zigzagging) up the hill to be able to get up when i would rather just go straight up. so yeah its a matter of getting tired, and not so much an issue of pain. as i get stronger ill start adding teeth to my chainrings.


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## axlenut (Sep 28, 2010)

Hi, a 44x16 is a 72.4 inch gear so it would be almost the same as the 46x17 (71.2) you had on the bike. Changing the rear freewheel cost less then changing the front chain rings so if you still have the 46 maybe consider putting it back on and trying a 18 tooth freewheel. That would give you a 67.2 inch gear. 18 to 20 MPH should not be a problem with a 67.2 inch gear.

Later, Axlenut


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