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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 05-18-05, 04:15 PM   #1
emayex
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48x16 is a bad gear combo if skidding is expected...correct?

should i try top stick with that prime rule?
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Old 05-18-05, 04:17 PM   #2
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So they say.

To be honest, I can't say that I've ever observed this, but it sure stands to reason. I can't think of any way reality wouldn't play out according to the theory.
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Old 05-18-05, 04:19 PM   #3
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depends - around 70/75 inches is good for starters
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Old 05-18-05, 04:20 PM   #4
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It seems to me that as long as you rotate your tires on the rim, or even just change where the chain falls on the cog rather regularly, you'd be fine.
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Old 05-18-05, 04:20 PM   #5
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dude....
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Old 05-18-05, 04:24 PM   #6
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Wow, how much time do you have on your hands?
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Old 05-18-05, 04:31 PM   #7
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A chain ring with 43t, 47t or 49t gives the same number of skid patches as the number of teeth on the sprocket.

I just now put a 47t chainring on my Pista, with a 17t cog, for 72.7 gear inches.
I didn't do it for the skid patches (I don't know how to skid) but rather because I wanted that specific gear inch.

Interestingly, I noticed I could put this chain ring on the outer position of the Sugino RD crank, and it looks 1000% better.
I flipped over the EAI sprocket, so the flange faces inboard, and I now have the most perfect chainline imaginable.
I mean perfect.
This didn't move the pedals, which leaves me with the same Q-factor or "tread" (as Sheldon puts it) as before, and so I can't think of any negative to this.
Looks good.
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Old 05-18-05, 04:32 PM   #8
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I have no trouble skipping with 48x16. I have been wearing through the tires pretty fast, though...
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Old 05-18-05, 04:48 PM   #9
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Quote:
Originally Posted by Ken Cox
A chain ring with 43t, 47t or 49t gives the same number of skid patches as the number of teeth on the sprocket.

I just now put a 47t chainring on my Pista, with a 17t cog, for 72.7 gear inches.
I didn't do it for the skid patches (I don't know how to skid) but rather because I wanted that specific gear inch.

Interestingly, I noticed I could put this chain ring on the outer position of the Sugino RD crank, and it looks 1000% better.
I flipped over the EAI sprocket, so the flange faces inboard, and I now have the most perfect chainline imaginable.
I mean perfect.
This didn't move the pedals, which leaves me with the same Q-factor or "tread" (as Sheldon puts it) as before, and so I can't think of any negative to this.
Looks good.
I'm not sure if my math is any good at the end of the day, but I think 49x14 is only going to give you 2 skid patches. Then again, if you're rockin' a 92 inch gear you don't need any advice from me ;-)

Last edited by r-dub; 05-18-05 at 07:08 PM.
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Old 05-18-05, 04:51 PM   #10
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I'm a skidder. I use 49x18. I need all the life I can get out of my tires. Even if it means believing in this voodoo called "mathematics".
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Old 05-18-05, 04:56 PM   #11
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before i killed the bike i was riding brakeless on 50x14...
not for everyone tho...
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Old 05-18-05, 05:09 PM   #12
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See this thread. Don't use 48x16 if you skid: with this combination a full revolution of the crank produces exactly three revolutions of the cog, so you'll always be right back where you started, leaving you with a grand total of one skid patch if you always skid with the same foot forward.
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Old 05-18-05, 05:50 PM   #13
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uhhh...damn, i took algebra and calculus but it was 20 yrs ago. so, if i have 48/18, that reduces to 8/3, or 2.6666etc, meaning 3 patches, correct?

i had no earthly idea.

very cool.
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Old 05-18-05, 06:31 PM   #14
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You can skid with ANY gearing if you practice...it might not be the ideal...but don't get up your gearing based the skid factor, base it on what you are comfortable riding, and then learn to skid with whatever gearing that may be.

I ride either 52/16 or 52/17 (brakeless) depending on the day and I can skid fine...I don't skid for show, I skid when I need to stop quickly only, but with toe clips and a little weight on the handle bars, its fine.
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Old 05-18-05, 06:35 PM   #15
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itll only give you, as said, three skid patches which is much less than desirable. i ride 50*16 and i think it works well. anyone have any idea how many patches that is?
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Old 05-18-05, 06:44 PM   #16
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Quote:
Originally Posted by honduraz10
itll only give you, as said, three skid patches which is much less than desirable. i ride 50*16 and i think it works well. anyone have any idea how many patches that is?
i believe that gives you 8 skid spots (if you skid with the same foot forward). if you skid with either foot forward, - i don't know how to do the math. in some cases the # doubles, in some cases it doesn't.
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Old 05-18-05, 06:48 PM   #17
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Here's a handy calculator that tells you how many skid patches a gearing will give you:

http://xjeffx.freeownhost.com/
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Old 05-18-05, 07:08 PM   #18
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if you are just a little mathematically inclined, you can always calculate your skid patch numbers on the fly. Divide the cog teeth number by all common denominators between cog and chainring. Whatever's left is number of skid patches. This is why the prime numbered chainrings give the most patches...no common denominators.
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Old 05-18-05, 07:14 PM   #19
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Also, there seem to be two different issues being discussed here.

1) skidding and tire wear - you want to choose a gear that allows for max skid patches.
2) ability to induce a skid in specific gears - not my forte, but I think this just depends on the person and the total gear size rather than specific combinations.
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Old 05-18-05, 07:14 PM   #20
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buddies

i can skid.....ive been around for a while

im just talking about skid patches...and i was just checking my own thoughts....wow
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Old 05-18-05, 07:46 PM   #21
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noisebeam posted this chart in this thread.

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Old 05-18-05, 07:49 PM   #22
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cool thanks for the chart...so my 52/17 looks awesome for skid patches..
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Old 05-18-05, 07:57 PM   #23
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Actually there are many other factors at work in determining the life of one's tire through skidding.

Skidding technique comes into paly a lot here. For example: if you can skid in multiple positions during the pedal stroke, then the number of skid patches will change.
Also the way you skid- If you just skid in a straight line, rather than 'powerslide/fishtail' the rear of the bike, the skidding wear will be different.

For some, myself included, when I lay down a big skid, tend to push the cranks backwards during skidding, so the rear wheel actually is traveling backwrads, but the bike is skidding forwards. I also like to let the pedals 'move' slightly when skidding forward and backwards- whihc also distributes the wear over the entire the whole tire more evenly.

Tire size, material and construction all are important when thinking about tire life and skidding.

So my friends, just the raw # of skid patches is not the only thing in play here.

My real life experience:After 1+ month riding 44x16 (4 skid patches), with lots of skipping, some skidding, has left me with a pretty evenely worn tire , probably due to the factors that I outline above.
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Old 05-18-05, 08:41 PM   #24
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i'm riding 48x16 right now and try not to skid but since drivers generally suck it happens more than i'd like. anyways, 48x16 feels awesome but i am going through tires pretty fast. i was thinking maybe going to 48x17 but i don't know how much that is going to change my riding. i like the cruising speed i achieve with this gear ratio but i also want to have more skid spots. i guess i just want to know how much different will it feel?
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Old 05-18-05, 08:55 PM   #25
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47/16 should feel pretty much the same.

I'm curious, do you find that your tires are excessively worn in any particular areas?
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