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-   -   Uncle Sixty's Gearing Primer for Newbs (http://www.bikeforums.net/singlespeed-fixed-gear/716371-uncle-sixtys-gearing-primer-newbs.html)

Sixty Fiver 01-20-12 12:18 AM

Quote:

Originally Posted by bigbris1 (Post 13707275)
hai uncle 60

Where has you been ?

Rehabbing those knees ?

BezO 01-25-12 09:03 AM

These are excellent descriptions! I went with 46/17 (73.5 GI) with a bailout of 46/19 (65.8 GI) on 700x35c tires.
Quote:

Originally Posted by puppypilgrim (Post 12506287)
60-65 gear inches = good for older riders or weak knees or touring.

66 gear inches = good all round gear for flats and hills. Not too slow on the flats, not too hard on the hills and wind. Touring is even possible. Great acceleration from standstill.

46/19... I've only ridden this a few miles just to test it out. Not too bad on flats but excellent on hills. My ride home always includes a one block long, fairly steep hill and this was perfect. Still challenging but way more fun being able to keep up some type of cadence. And the mile of slight incline before the hill was great.

Not enough GIs to be my all around gearing though. A little too much spin on flats. I'll see if I'm up to switching gears for the commute home everyday.

Quote:

Originally Posted by puppypilgrim (Post 12506287)
70-73 gear inches = superb range. At 100 rpm, it produces 21.4 mph (34.5 km/h). At 100 rpm, the force required to turn the pedals is still relatively light. Anything is this gear range produces an excellent balance between acceleration, hill climbing, combating winds and flat road speed. Note that at 20 mph (32.2 km/h), approximately 80% of the power being produced by the human body is being used to overcome air resistance. This is why it is so hard to sustain any speed above 20 mph (32.2 km/h) during a daily commute. If you know how to spin, this gear range will not be slowing you down.

46/17... pefect all around gearing for me. I've commuted 2 1/2 times with this gearing. I immediately noticed the difference from 46/16. Much better acceleration. More spin at top speed. I don't have a speedometer, but I felt I was as fast as I was with 46/16. Fun on slight upgrades and not that bad on that one block long hill to get home.

I can't wait to try both gearings this weekend in the park. I'm guessing 46/17 will be near perfect; great on flats and quite challenging, hopefully still fun on the inclines. While 46/19 will be great for the inclines and not so great on the flats and declines. I'm sure it will be fun trying both.

GENESTARWIND 02-12-12 03:50 AM

I started on 46/18 with single and dropped to 46/17 on my first fixed setup. its good so far.

Jaytron 02-22-12 11:40 PM

Quote:

Originally Posted by GENESTARWIND (Post 13841514)
I started on 46/18 with single and dropped to 46/17 on my first fixed setup. its good so far.

Wouldn't that be gearing up, not dropping? :)

blissofbeing 03-05-12 08:04 PM

When I first starting riding fixed (around town not on the track) it was a 47/16 which is a 77.5, and I found it too low. Maybe I wasn't used to spinning so much, I felt like I was topping out and I couldn't go faster.

After awhile I upped it to a 47/15 (82.7) and I kept it at that. I ussualy ride about 20 miles a week commuting back and forth from my girl friends, my ride home has a pretty steep hill, but not that bad (~500ft climb total distance), and though I had to really push up the hill, I was OK with it.

When I built my new all city bike the chain ring I got was a 46, and I ordered a 15t and 14t for each side of the rear cog. When I first put it together I ran a 46/15 (80.9) which was actually pretty nice around town.

A couple weeks ago I flipped my rear tire to the 14t and have been riding the 46/14 (86.7) around town since then, and I honestly feel a bit slower on it than any of my other ratios. I just can't keep up my spin at that ratio, not in the city anyways.

So now with all this knowledge of what its like -for me- to ride a 77.5,80.9,82.7, and 86.7 I feel like for me something in the high 70s low 80s is ideal for me. I'll probably switch my hub around and ride the 80.9 for around the city.

My whole point in all of this is that its important for YOU to try a bunch of different ratios. I personally feel like @Sixty Fiver and @puppypilgrim recommendations are a little too low for me. But most of my friends actually ride between a 70-75 tops and most other forms I read people talk about 75 being too high for them. Is it just me or does anyone else get frustrated at low to mid 70s? Seems like I might be an outlier, or maybe I haven't figured out/don't want to spin that fast to go fast. ;)

Sixty Fiver 03-05-12 10:52 PM

Quote:

Originally Posted by blissofbeing (Post 13936167)
My whole point in all of this is that its important for YOU to try a bunch of different ratios. I personally feel like @Sixty Fiver and @puppypilgrim recommendations are a little too low for me. But most of my friends actually ride between a 70-75 tops and most other forms I read people talk about 75 being too high for them. Is it just me or does anyone else get frustrated at low to mid 70s? Seems like I might be an outlier, or maybe I haven't figured out/don't want to spin that fast to go fast. ;)

Most of your friends probably spin like gerbils on crack and you said you ride 20 miles a week... I used to ride 265 miles a week on a single gearing of 76 GI so running that gearing in the mid seventies was also about endurance and having a gear for every situation.

I also use to ride at 80 gear inches and laid down the same mileage... dropping 4 gear inches just let me spin up a little faster and did not affect my top speed save for the fact I could hold it longer and keep things steadier over varied terrain.

ATleastHEtries 03-10-12 10:47 AM

what range is my gear ratio? im running 48-18 just droped down from 48-16.

Scrodzilla 03-27-12 06:44 AM

Extra medium.

jlind 03-27-12 08:53 AM

Quote:

Originally Posted by ATleastHEtries (Post 13955071)
what range is my gear ratio? im running 48-18 just droped down from 48-16.

Precisely, it's now 8:3 down from 3:1 (or 24:9 down from 24:8).

GENESTARWIND 04-19-12 10:28 PM

so right now I run a 17/46 and I may be picking up omniums on the super cheap but it has a 52 chainring. what size cog would I have to drop to, to keep the same setup?

Nagrom_ 04-19-12 10:33 PM

Quote:

Originally Posted by GENESTARWIND (Post 14121439)
so right now I run a 17/46 and I may be picking up omniums on the super cheap but it has a 52 chainring. what size cog would I have to drop to, to keep the same setup?

17/46? 9.75 gear inches. I like it.

46/17 = 71.4GI

52/18 = 76.2GI
52/19 = 72.2GI
52/20 = 68.6GI

Take your pick.

Spoonrobot 04-19-12 10:34 PM

52/19 is just a hair larger.

GENESTARWIND 04-19-12 10:40 PM

so 52/19 I shouldn't notice much of a difference?

bfloyd6969 04-20-12 08:00 PM

Quote:

Originally Posted by GENESTARWIND (Post 14121462)
so 52/19 I shouldn't notice much of a difference?

Not too much.

GENESTARWIND 04-25-12 03:33 AM

turns out the crankset i bought had a 49, not a 52. so ill be running 17/49 for now, see how i like it and maybe ill jump up to a 18 later i dunno..

Skinner 08-18-12 10:28 AM

Hello! I'm gathering information for my MTB to fixed commuter conversion.
Sorry if this question has been asked already, but is there any difference between 38/15 gearing and 42/17 or 45/18 gearing? All give 2.5 gain ratio and 65 gear inches for my 26 wheel.
Logically the 38/15 will weight less, but will it ride the same as 45/18?

Spoonrobot 08-18-12 11:15 AM

It's generally accepted that larger chain-rings and cogs wear slower than smaller combos so you'd probably want to use the 45/18 gearing. Weight difference should be negligible and all should ride the same if they have the same gain/gear inches.

tomatsu 08-18-12 12:18 PM

Quote:

Originally Posted by Skinner (Post 14621952)
Hello! I'm gathering information for my MTB to fixed commuter conversion.
Sorry if this question has been asked already, but is there any difference between 38/15 gearing and 42/17 or 45/18 gearing? All give 2.5 gain ratio and 65 gear inches for my 26 wheel.
Logically the 38/15 will weight less, but will it ride the same as 45/18?

Also be sure you have the chainstay clearance for the 42t or 45t chainrings. My MTB conversion just barely took a 41t on a single speed crank.

silmarillion 10-17-12 11:25 AM

Who has the best selection of chainrings/gears? I did a search in google but got tired of wading through hundreds of BMX parts...


What brands are the best?

Spoonrobot 10-17-12 12:31 PM

I like Retro-gression for cogs and Bens Cycle for chainrings.

Locally, Loose Nuts in Grant Park has (or had, it's been a while since I've been there) a good selection of fixed gear stuff since they got a bunch of stock when No Brakes closed.

If you're not picky about running 3/32 stuff you can usually find some good used cogs/rings at So-Po.

silmarillion 10-17-12 01:51 PM

Thanks!

I'll check them out. I want to get a bigger chainring for riding on the flats. I think the 46 is fine for the commute, but I need a little more if I ride flat terrain.

prooftheory 10-17-12 01:59 PM

Quote:

Originally Posted by silmarillion (Post 14851795)
I'll check them out. I want to get a bigger chainring for riding on the flats. I think the 46 is fine for the commute, but I need a little more if I ride flat terrain.

Did you actually read the first post of this thread? I'd recommend it.

silmarillion 10-17-12 06:52 PM

Quote:

Originally Posted by prooftheory (Post 14851826)
Did you actually read the first post of this thread? I'd recommend it.

Well yeah. I read through most of the first posts...Good stuff. Her' post Nazi.

prooftheory 10-17-12 07:20 PM

Then why do you believe that a 46t chainring is too small "for flats"?

silmarillion 10-17-12 07:45 PM

Quote:

Originally Posted by prooftheory (Post 14852813)
Then why do you believe that a 46t chainring is too small "for flats"?

Because my cadence is too high on the flat areas I do ride. If I go to the the Silver Comet Trail, which is pretty flat. I would like to be able to ride a little faster and keep my cadence around 100-110.

Is this a bad thing? If it is, then I guess you got me.

Sorry I asked.


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