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Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

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Old 04-07-10, 08:30 PM   #1
Thrahl
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Should I Change My Gear Ratio or Keep It?

Right now I am running 42x16 and it feels like a am pedaling a bit too slow most of the time.
I only recently bought this bike and started to actually ride decent distances (10-15 miles every few days at an average of about 15-16mph).

I am wondering, should I buy a slightly larger cog, 17 maybe 18, or should I keep riding and wait for my legs to get stronger and consequently increase my average speed?

According to Sheldon Brown's gear calculator, with 42x16 @ 90 rpm, I will be going 18.8mph.
I can't keep a nearly 19mph constant for more than maybe 3-5 miles before I am tired.

42x17 on the other hand is 17.7 @ 90rpm and 42x18 is 16.7, both of which seem a bit more reasonable.

Right now, I am pedaling at nearly 80rpm which from what I have read is less than optimal and can tire my legs out faster as well as put more pressure on my knees.

ANYWAYS, what would you suggest? Keep the 16 and build some muscle or up to 17/18 and spin at the optimal amount?

Thanks for any help.

PS: and btw, I live in Florida where there isn't a hill within 20 miles (besides overpasses) so that is not an issue
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Old 04-07-10, 08:42 PM   #2
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Get an 18 and then work your way down. I was running 48x16 and was wondering why I was going so slow... and then I switched to a 17 and immediately picked up speed. I can go fast without spinning out and I don't have to worry about hills (other than bridges) as I live in FL too.
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Old 04-07-10, 08:42 PM   #3
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Absolutely, gear down if you feel uncomfortable in that gear. You will actually be able to sustain that speed longer. I'd suggest, trying the 17T first, and seeing if you can maintain 90 rpm w/o getting tired. Eventually, you can return to the 16T, once you gain strength and endurance. FWIW, I ride between 38 x 16 and 42 x 16, which is roughly the same as 42 x 18 and 42 x 16.
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Old 04-07-10, 09:10 PM   #4
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If you're running 42 :16, why would you get a bigger 17 or 18 cog? That would lower the gearing.

To me, running 69 gear inches is a very low gear.
Since you live in a flat area, I recommend you get a much higher gear. At least something in the mid-high 70s like 48 : 16.
But if you prefer spinning, then don't gear up as much, maybe around 46 : 17.
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Old 04-07-10, 09:20 PM   #5
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I am running 46x15 right now, but on my new ride am switching to 49x17.
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Old 04-07-10, 09:34 PM   #6
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I ride 49x16 and 52x17. I like the feeling of the higher gear if I'm going slow through traffic.
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Old 04-07-10, 09:54 PM   #7
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I used to run a 42x16 when my bike was single speed and I found that I spun out way too easily. I say keep that gearing for now because it felt just right for me. When I converted my bike to fixed, I switched my COG to 13T.
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Old 04-07-10, 10:20 PM   #8
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honestly did u just start riding? that's all i can think of as to why you would be considering gearing down.... if you buy a larger cog, your legs will spin faster BUT you will move slower, significantly so. a ratio of 42 x 18 is honestly ridiculous for riding on the road, especially in the topography that you describe. i'd recommend to just keep riding what you have for a bit. your legs will get stronger and you wont have to spend any money. also, with your chainring at such a small size you are putting more stress on your drivetrain than you would if you were running a higher gear ratio ( I run a 49 x 17 for instance).
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Old 04-08-10, 08:37 PM   #9
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Sorry for the late reply, I have been busy.
Basically, I have been riding a bike for a long time but have just recently (about a month ago) bought a "real" bike and actually started to learn about cycling.
I ride mainly for commuting and just for the fun of it.
I prefer fixed gear over geared because of the simplicity and the efficiency.

From what I have read, 90 to 100 rpm is ideal and will be most efficient.
For me to pedal at 90 to 100rpm I am going at a speed faster than I am able to hold for very long, as previously stated.

I figured that with a lower gear ratio, I would be able to reach 90 to 100 rpm while maintaining a more reasonable speed.

I don't know when exactly "spinning out" occurs but I seem to not be able to go much faster than about 28mph at my gear ratio which is much faster than I ever need to go.

I would imagine that with a 18 tooth cog I would be able to achieve 90-100 rpm fairly comfortably and sustain that speed for much longer therefore increasing my overall efficiency.
I could still hammer up to 24-25mph if I wanted to but I only go that fast if I am racing or just messing around.

I don't understand how someone could run something like 46x15 on a fixed gear seeing as you would basically be mashing constantly (or riding at 22mph most of the time, in which case bravo)

So I think I am going to end up getting the 18 tooth and just riding that until I feel that I am spinning out the gear and then I can just change back to the 16.

Thanks for the help.
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Old 04-08-10, 08:55 PM   #10
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I think you have a very sensible plan. It doesn't matter what gearing other people use, but what you find comfortable and efficient. One thing I would suggest is to not jump from an 18 to a 16, but to first go to a 17 for a while before going to the 16. One way to assess your progress is to get a heart monitor, and watch your heartrate. Over time as you gain fitness, your heartrate at your set speed will drop. Best results will be obtained with your sustained heartrate between 65% and 85% of your maximum.
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Old 04-08-10, 11:31 PM   #11
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Tejano makes a valild point: that all that really matters is what feels comfortable and efficient, not what we, the random people on the internet, find permissible. I guess what it really boils down to is what is comfortable to you? I, personally, don't like keeping a high cadence on flat just to keep up with my friends who all have a higher gear ratio (I actually rode 42 x 16 for a while, it's a great beginner gear for learning fixed) you, on the other hand, may like to keep up a higher cadence. If you do decide to switch parts, make sure to keep your old stuff so that you can do the inevitable gear up when your new ratio becomes to easy to push. I've been riding 49 x 17 on hills for a while and am happy with it but its starting to get too easy. Then again I'm also about to build a road bike (c'mon tax dollas!!!!) so I'll probably just leave well enough alone.
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Old 04-09-10, 05:29 AM   #12
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No one can tell you what gear ratio is best for you. If you are serious about FG/SS riding, the best advice would be to buy a few cogs, learn how to change them, and experiment. With more experience you'll develop a good understanding of what gear ratios work for you and when to use what gear ratio. For riding on the streets, I use several gear ratios ranging from 39/16 (lowest, used in the winter with cyclocross tires) to 49/16 (highest, used in warmer months for high intensity road rides). I also ride several intermediate ratios. The ratio I select depends on the time of year, where I am riding, how far and how fast I intend to ride, my current fitness level, and a lot of other variables. If I had to chose one gear ratio, it would probably be somewhere around 72"-73", but, of course, I rarely ride that gear...its usually above or below that.

Riding offroad is another area that involves careful gear ratio selection. After years of riding singletrack fixed and ss, I've developed a refined sense of what gear ratios work best for specific trails and my ratios range between 34/22 to 34/14. Understanding gear ratios and how to choose them is an important skill for the SS/FG rider and something that most geared riders and many FG/SS riders are totally clueless about.

Last edited by mihlbach; 04-09-10 at 05:34 AM.
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Old 04-09-10, 12:37 PM   #13
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Thrahl, I think you are misunderstand how gearing works.

"From what I have read, 90 to 100 rpm is ideal and will be most efficient."

Where have you read this? And what do you mean by "most efficient?" And why would you care about efficiency, whatever that means? You're immersing yourself in a new physical activity that takes work. (I'm guessing by " most efficient" you "easiest.")

"to pedal at 90 to 100rpm I am going at a speed faster than I am able to hold for very long"

You've not been riding very long. Keep riding.

"I would imagine that with a 18 tooth cog I would be able to achieve 90-100 rpm fairly comfortably and sustain that speed for much longer therefore increasing my overall efficiency."

It turns out, though, that to ride a given distance, 90 rpm is going to take about the same amount of energy no matter what gear you're in. Work equals force times distance. For a given distance with a larger cog, it's easier to turn the pedals, but you have to turn them more often than you would with a larger smaller cog, so it's a wash.

Here's an interesting link about John Howard's 152 mph ride which set, at the time, the land speed record for a bike. Howard's bike, with it's huge, single gear, was towed up to a high speed on the famed Bonneville Salt Flats, and he rode behind a motor vehicle which knocked out the problem of air resistence.

Here's a bike with a huge gear ratio (that can barely be ridden a slow speeds):




I'm not saying you shouldn't get another cog and try it out, but it won't make it any easier for you if you intend to turn the pedals at the same rpm.
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