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# Gear ratio

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# Gear ratio

02-17-18, 11:52 PM
#1
Godspeed7
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Gear ratio

Any one know a good gear ratio for riding in hilly areas on a fixed /single speed?

02-26-18, 03:33 PM
#2
fietsbob
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You say little how steep, what hill?, how strong are you, what have you tried so far..

Math..
Rear cog T divides front chainring T .... example 20 cog 40 chainring is 1:2, 1 rotation of the crank turns the wheel twice.

then measure your wheel size .. inch diameter .. 2:1 x 27" = a 54" gear ..

that is the math, remember that from school?

A hill, like stairs have measurements ... distance traveled, elevation gained.. that too can be expressed as a ratio.

so how steep/ hilly, ? and what gear? have numbers to define them..

....

Last edited by fietsbob; 02-27-18 at 06:10 PM.

02-26-18, 04:05 PM
#3
kingston
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02-26-18, 04:11 PM
#4
fietsbob
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03-30-18, 05:43 PM
#5
Dean V
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77" works for me. As long as the hills are less than a mile long and under 10%.
It is also very dependant on your weight, fitness, pedalling preference.
Trial and error is really the only way to find what suits you.
Also fixed you will probably want a bigger gear than single speed as you can't coast on the downhill.

03-30-18, 07:32 PM
#6
markwesti
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03-30-18, 07:58 PM
#7
Dean V
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I can't see how gear charts, calculators etc help.
It is a balancing act between how big a gear you can push up the hills and how fast you can spin down them.
No calculator will tell you that.
You just have to try it out. A handful of different rear sprockets is not that expensive.

04-08-18, 04:48 PM
#8
Godspeed7
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Thanks for the info.

04-08-18, 04:53 PM
#9
Godspeed7
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Originally Posted by Dean V
I can't see how gear charts, calculators etc help.
It is a balancing act between how big a gear you can push up the hills and how fast you can spin down them.
No calculator will tell you that.
You just have to try it out. A handful of different rear sprockets is not that expensive.

06-13-18, 03:16 AM
#10
fixiewarrior.
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46:15 is what I use for hills pretty climb friendly set up

06-13-18, 06:17 AM
#11
kingston
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Originally Posted by Dean V
I can't see how gear charts, calculators etc help.
It is a balancing act between how big a gear you can push up the hills and how fast you can spin down them.
No calculator will tell you that.
You just have to try it out. A handful of different rear sprockets is not that expensive.
I agree that you need to try out a few and see what works, but I have been riding fixed for a while, have a bunch of different gears, and sill use the calculators. Yesterday I went for a little 25 mile ride, and my top speed was just over 31 mph. I was spinning like crazy, so I thought about changing to a higher gear when I got home. I used the bikecalc cadence at speed calculator to determine that I was spinning at over 150 rpm at my top speed, which is about my limit. My average speed for the ride was a little over 19 mph, which means I spent most of my time on the flats in the 20-21 range, which is a cadence of around 100 rpm. If I add two teeth on the chainring it drops it down ~5 rpm or I could drop a tooth on the sprocket to bring the rpm down by ~7, but then I'd have to shorten the chain, so a bigger chainring seems like the way to go. I guess I could have just started swapping parts, but it's nice to have some idea of what's going to happen before I make any changes.

06-13-18, 06:23 AM
#12
Geegee
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Originally Posted by Dean V
I can't see how gear charts, calculators etc help.
It is a balancing act between how big a gear you can push up the hills and how fast you can spin down them.
No calculator will tell you that.
You just have to try it out. A handful of different rear sprockets is not that expensive.
i don't get them at all. Big number for big hills. Dont know.

06-25-18, 01:03 PM
#13
fietsbob
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06-25-18, 01:42 PM
#14
79pmooney

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As others said above, you have to see what works for you. I'm a hill climber, Love out of the saddle climbing. I have also been riding fix gear a long time. Long enough tha the reality that I am no longer a 20 something has sunk in.

I started riding in an 81" gear. (For gear inches, divide chainring teeth by cog teeth and multiple by wheel diameter. For road 700c, use 27". So 42 /14 X 27 = 81" for example.) The vets in my racing club quickly told me to reduce my gear to 42-17, 16 as I got strong through the season, (By the season end, as a strong racer, I was riding a 15.) I was strong enough to climb just about anything (at real cost!) with those gears. Now, coming down I always had brakes. In those days, it never seriously occurred to most of us to ride without. We were riding for training and brakes allowed us to ride faster (better training) and avoid crashes (potentially real setbacks in that same training).

So my advice? Have a lockring spanner and chain whip, put on a smallish chainring (42,43 or 44) and buy several cogs. 15 through 18 would be a good start. Experiment. When you look at your next rear wheel, seriously consider a flip-flop hub, fix-fix. Then you can leave for your ride with say a 16 and a 17, You can even go totally crazy like I did 7 years ago and have a custom fix gear made that you can run from 12 to 24 teeth on and buy all the cogs. Carrying a chainwhip, I can ride up true mountains then come down in a gear that is really fun. (That bike has ridden to, up and around Crater Lake.) But like fix gears 100 years ago, I have to plan ahead. It takes me 2 minutes to flip my wheel and 5 to change out a cog. I still do a lot of hills the old way, grunt up and spin down just like when I started 42 years ago (almost exactly today!)

If you haven't gotten very far into buying cogs and chainrings, seriously consider going to an all 1/'/8" setup. (There are two single spee/fix gear standards: 3/32" which is the 1960s and '70s 10-speed standard chain and gear teeth width and 1/8" which is the oldest standard and still used on kids single speeds, IGH setups and on the track. (Both are used on the track, but the 1/8" is more common and the preferred for the stronger riders. 1/8"{ has two advantages for you: longer wearing - both chain and gear teeth - and more resistance to being thrown off when spinning fast - a bigger issue for riding road hills than on the velodrome.

I'm guessing you are relatively new to fix gear riding. Welcome! It's a great journey!

Ben

06-25-18, 01:53 PM
#15
79pmooney

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Originally Posted by kingston
I agree that you need to try out a few and see what works, but I have been riding fixed for a while, have a bunch of different gears, and sill use the calculators. Yesterday I went for a little 25 mile ride, and my top speed was just over 31 mph. I was spinning like crazy, so I thought about changing to a higher gear when I got home. I used the bikecalc cadence at speed calculator to determine that I was spinning at over 150 rpm at my top speed, which is about my limit. My average speed for the ride was a little over 19 mph, which means I spent most of my time on the flats in the 20-21 range, which is a cadence of around 100 rpm. If I add two teeth on the chainring it drops it down ~5 rpm or I could drop a tooth on the sprocket to bring the rpm down by ~7, but then I'd have to shorten the chain, so a bigger chainring seems like the way to go. I guess I could have just started swapping parts, but it's nice to have some idea of what's going to happen before I make any changes.
I used to ride up to Skyline Blvd over Oakland, CA from the sea level island of Alameda (Juaquim Miller), turn around at the top without stopping and fly down. Despite being 2 lanes on either side of a parkway median and California drivers, I was never passed on the way down. (45 mph?) Always a 42 x 17. 225 rpm? Yes, it was completely nuts. (And yes, when I rolled back into Alameda, I did not have a single tight muscle in my legs from that 1000' climb!) Oh, I used aluminum slotted cleats and quality Binda toestraps pulled tight!

I am no longer that crazy.

Ben

06-25-18, 01:58 PM
#16
kingston
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Originally Posted by 79pmooney
I am no longer that crazy.
That's amazing. I start to feather the brakes at around 150 so I don't bounce off the bike.

06-25-18, 04:42 PM
#17
79pmooney

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The bouncing is because you aren't relaxing your leg muscles completely. The more completely you relax, the more fun, faster and safer downhills become. And you get to benefit all the rest of the time too; both riding fixed and on gears since your muscles aren't fighting other muscles that aren't completely relaxed. (The two great techniques for practicing that relaxation are fix gear downhills and riding rollers. Both are not fun at all until you teach your legs that skill.)

A comment re: chain length - any good fix gear chain can be riveted repeatedly with no issues at all. Just make sure you have good (and equal) pin extension beyond the plates. I stay away from the "sexier" chains with shorter pins. (The one KMS 1/8" chain I bough had considerably less pin extension than the Izumi chains I usually use. Yes it ran quieter, but I am much more interested in the chain simply working!)

Ben

06-25-18, 05:12 PM
#18
kingston
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Originally Posted by 79pmooney
The two great techniques for practicing that relaxation are fix gear downhills and riding rollers. Both are not fun at all until you teach your legs that skill.
I'm pretty sure my skills have plateaued. I ride rollers all winter and most of my early season training fixed. By this time of year I'm riding mostly geared bikes outside. There aren't really any hills where I live so I'm fine with a max rpm of ~150.

08-13-18, 01:38 PM
#19
STSCOWBOY
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Originally Posted by Godspeed7
Any one know a good gear ratio for riding in hilly areas on a fixed /single speed?
Thats too subjective a question.

How many watts can you produce, how fast can you spin, how steep/long are the hills to name a few.

08-18-18, 10:54 AM
#20
Thetank
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Get on a geared bike, ride the hills and find out what gearing you're most comfortable at and match the gearing to your fixed gear.

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