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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 05-25-11, 04:46 PM   #1
Anthropy
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Changing from 71 to 69 gear inches - any benifits

I am running 71 GI and like going down the hills and up moderate hills. But sometimes, I would like a little more ease at hills.

Would I notice a lot by dropping to 69 GI?


Tom
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Old 05-25-11, 04:52 PM   #2
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I like 69 gi (42x16) for around town commuting, but you really have to spin like a madman on the way down a hill. How is descending for you now?
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Old 05-25-11, 05:10 PM   #3
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I am running 71 GI and like going down the hills and up moderate hills. But sometimes, I would like a little more ease at hills.

Would I notice a lot by dropping to 69 GI?

Tom
Not a lot. You'll probably notice it, though.

Fun Fact: I run 66.6 gear inches

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Old 05-25-11, 05:20 PM   #4
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I run the devil's ratio too and don't have an issue with spinning out on descents. Probably because I'm riding toward Hell.
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Old 05-25-11, 05:27 PM   #5
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I don't totally understand this gear ration thing yet. What would happen if I went up? I'm running a 42/16 (69 GI) single speed.
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Old 05-25-11, 05:31 PM   #6
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I use to run 63 GI (42x18 & 32c tires) and the hills were pretty easy, but I don't spin very well, plus going down hills sucked more. I wanted faster so I changed to 71 GI (42 x 16), which is better going down hills, but I still use the hand brakes to help slow me down. I thought of going to a 42x17 = 66.7 GI, to see if that was better. I like 71 for the straight ways, but this spring we have had a lot of 30 mph head winds that equal NO Joy. I am running 165mm crank arms.

I want something that is a tad bit easier on my knees (they hurt a lot some days), but will still give me some speed. I sometimes think that single speed is where I need to end up, but fixed had been so much fun this year, I hate to give it up.

Tom
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Old 05-25-11, 05:32 PM   #7
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I run 67 GI and only spin out when I'm booking it down the occasional hill we have in central Illinois.

A 2 GI difference is not a lot. Noticeable, but barely so.
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Old 05-25-11, 05:35 PM   #8
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I don't totally understand this gear ration thing yet. What would happen if I went up? I'm running a 42/16 (69 GI) single speed.
The bigger the gear ratio, the easier it is to go faster, but it takes more leg power to move. Lower ratios make it easier to pedal, but you don't go as fast if pedaling at the same speed as the larger ratio. Big is hard on legs and knees. If you can spin like the wind, or as 65er said one day "spin like a gerbil on crack" you can go just as fast as the big gear guys. Small gears suck going down hills. Remember, the only time you can stop pedaling is when you 1)take your feet of the pedals, or 2) you stop.
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Old 05-25-11, 05:40 PM   #9
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Hey Scrod. You have any 17 t cogs in stock?
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Old 05-25-11, 06:22 PM   #10
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I've been alternating between 18, 17, and 16 tooth cogs with my 46t chainring to get 69.8, 72.5, and 76 gear inches, respectively.

Are there noticeable differences going one-step up or down between the three? Yes, but not soo much.

A more noticeable difference is going for a 2-tooth difference.

If you want to just adjust your GI a few inches, then try a smaller width tire, like going from 28c to 25c or 25c to 23c.
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Old 05-25-11, 06:24 PM   #11
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Hey Scrod. You have any 17 t cogs in stock?
Yes sir.
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Old 05-25-11, 07:22 PM   #12
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Appreciate the offer, OP. But no. Not at that ratio.
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Old 05-25-11, 07:27 PM   #13
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Was I offering something? I'm so confused.


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Old 05-25-11, 07:32 PM   #14
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benifits

Though, I do suggest spinning.
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Old 05-25-11, 07:41 PM   #15
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Spinning? Whirling Dervishes?


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Old 05-25-11, 07:49 PM   #16
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Embedding skills.

Last edited by rustybrown; 05-25-11 at 07:51 PM. Reason: I luvs scrods
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Old 05-25-11, 09:32 PM   #17
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Does gear ratio affect the ability to perform wheelies or ride backwards? or any other kinds of "tricks?"
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Old 05-26-11, 07:44 AM   #18
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I'd imagine, because if you watch videos of bicycle acrobats and whatnot, they're front chainring is like, a 20 tooth or something crazy.
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Old 05-26-11, 09:44 AM   #19
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Does gear ratio affect the ability to perform wheelies or ride backwards? or any other kinds of "tricks?"
A short ratio allows you to accelerate quicker - in both directions. Takes less power to lock up and skid, it's easier to stop by backpedaling or ride backwards. If I had a lower gearing (I run 49x15, though that's about to change), I'd have an easier time track-standing - I'm having trouble balancing the back-and-forth acceleration the way it is. IIRC, acrobatics sometimes run 1:1 ratios.

Try initiating a wheelie on a geared bike - the power-surge on a low gear will make it easier than a high gear. I nearly flipped this week on an uphill climb with my road-bike because I left it in the granny gear when dismounting for a drinking-break. When I got going again on the uphill, that first stroke lifted my front into the air.
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Old 05-26-11, 02:07 PM   #20
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Most trick track riders i know are right around the 68 gear inch area on thier trick bikes, which isnt especially low, but lower than most people's street gerings.
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Old 05-26-11, 07:58 PM   #21
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I forgot I had an old Sugino AT 170mm crank set with 50 / 45 chain rings I could try, so I pulled off the existing crank arms, stuck these on with the 45t and added a couple of links to my chain. Took it out for a test drive and found it much easier on my knees, spinning is easier, and I can take the hills a lot easier. So this gets me 67.5 GI (45/18) and I did not seem to loose any over all speed. So, I would be in the same ball park if I had done 42/17 (66.7), which I might still do, but at least this test was pretty much free.

Now, I need to get the hang of not bouncing so much when I try and spin like mad.

Tom
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