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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 06-06-09, 01:03 PM   #1
Saberhead
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Wheel placement on dropouts

I changed out my chain a bit ago, and my friend who works at our lbs told me that when I change my chain I should place the wheel in the middle of the dropouts, have the chain be slightly longer, and not have it in the front of the dropouts(where it usually is).
Over time, the more I started skidding, I guess the wheel was progressivly getting closer and closer to the front causing the chain to becomes looser and looser, until it jumped off the chainring yesterday causing me to get into an unpleasant situation. Might I also add, since putting the wheel here, the chain has fallen off 3 times in the last month.

So, was there any logic to having the wheel placed in the middle of the dropout? It just seems like putting the wheel in the front of the dropout is a better idea since it's moving towards that point anyway, and this prevents the chain falling off. Where do you guys have your wheels placed? Does it make a difference? Maybe we just installed this on really badly..
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Old 06-06-09, 01:06 PM   #2
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mine is at the very back of the dropouts. It makes it easier to take off wheel and i have good chain tension. It really sketched me out at first b/c I thought my wheel was going to fall out of the dropouts or something but 2 good mechanics told me it was fine so I kept it that way. They said that as long as the axle bolt is completely covered by the dropouts that it would be fine.

If you put your axle too far forward in the dropouts then it's tough to get the chain off in order to remove the wheel and change the tire.
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Old 06-06-09, 01:08 PM   #3
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I personally place the rear axle toward the middle of the drop out as well. Reason being that it'll be a lot easier to get the chain off when you need to change a tire/tube while out on my bike. I never had a problem with the wheel getting loose and the chain falling off though. Maybe you didn't tighten it enough or the teeth on your track nuts are worn and are flat.
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Old 06-06-09, 01:12 PM   #4
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The wheel moving forward has nothing to do with axle placement in the dropout, and everything to do with the tension you put on the chain and the tightening method you use on the bolts/skewer. How do you go about doing those two things, and what tool do you use to tighten the nuts/skewer?
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Old 06-06-09, 01:18 PM   #5
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tighten axle nuts harder, tension chain tighter.

your chain should never derail with some good preventative maintenance.
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Old 06-06-09, 01:31 PM   #6
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wheelies are easier w/ it in a forward position
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Old 06-06-09, 01:42 PM   #7
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I think installing it badly might have been the culprit, and it makes sense that skidding loosened it. I had him retighten everything after I was done just to make sure I tightened the bolts enough, its just annoying how its happened so much.

So basically, it doesnt matter where you put the wheel in regards to placement in the dropouts, its all about chain tension and tightening bolts better?
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Old 06-06-09, 02:03 PM   #8
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skidding has nothing to do w/ anything..you put way more pulling force on the axle when you crank down hard
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Old 06-06-09, 02:07 PM   #9
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When I first got my bike, one afternoon of riding over curbs made by rear wheel tilt to the right by about 10 degrees. I readjusted it and tightened the f out of the bolts, and it hasn't budged. I'd put the wheel anywhere between the end and the middle of the dropouts to, like people said, make it easier to get the chain off. But yeah, your problem is probably just a bolt that's not tight enough.
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Old 06-06-09, 04:40 PM   #10
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As mentioned, as long as the axle nuts bite completely into the ends, you're fine. It doesn't take much forward movement to walk the chain off the chainring with a simple rotation, btw. You don't need to be able to lift the whole thing off at once. Positioning in the back half of the slot is OK if you never plan to change cogs to a smaller one later in the season.

That being said, it's not always possible to position it exactly where you want. Sometimes, the combination of front ring and cog make for a situation where you just have to accept what you get.
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Old 06-06-09, 10:36 PM   #11
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Sounds like someone needs a good wrench and a tensioner.
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Old 06-07-09, 12:22 AM   #12
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Quote:
Originally Posted by adaminlc View Post
Sounds like someone needs a good wrench and a tensioner.
Someone needs good arm muscle
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Old 06-07-09, 01:44 AM   #13
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either your track nuts suck or you're just not using enough torque. or both. axle placement in the drop outs is largely irrelevant.

if you dont have the strength to tighten properly, just get a 15 with a long[er] handle for better leverage. I have a peanut butter wrench and a park tool pedal wrench (pw-3) that are both great for leverage at home.

chain tension is one of the things you should check often so you dont throw your chain. I ride everyday and inflate my tires every other day -- when I do so, I also check my chain tension. Get a routine going and be mindful of the condition of your bike and you wont have such mechanical problems. Throwing your chain 3x in a month is rather ridiculous -- maintain your bike.

Last edited by Geordi Laforge; 06-07-09 at 03:13 AM.
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Old 06-07-09, 02:19 AM   #14
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Quote:
Originally Posted by Saberhead View Post
I changed out my chain a bit ago, and my friend who works at our lbs told me that when I change my chain I should place the wheel in the middle of the dropouts, have the chain be slightly longer, and not have it in the front of the dropouts(where it usually is).
Over time, the more I started skidding, I guess the wheel was progressivly getting closer and closer to the front causing the chain to becomes looser and looser, until it jumped off the chainring yesterday causing me to get into an unpleasant situation. Might I also add, since putting the wheel here, the chain has fallen off 3 times in the last month.

So, was there any logic to having the wheel placed in the middle of the dropout? It just seems like putting the wheel in the front of the dropout is a better idea since it's moving towards that point anyway, and this prevents the chain falling off. Where do you guys have your wheels placed? Does it make a difference? Maybe we just installed this on really badly..
You have 2 issues.

1) Chain tension
2) Your rear wheel is sliding in the dropout

Chain Tension:
I think that person was referring to how long to cut the chain. NOT how to position the wheel for use. I think you misunderstood him. If you cut it too short, then you can't use bigger rings/cog combos. If you cut it too long, you can't use smaller rings/cog combos.

When setting the wheel which sets the chain tension for actual use, think of a chain like a bracelet. Too lose and it will fall off. Too tight and it will be restricting. If you have a 48x16 gear the rear wheel will be in one spot. Then if you decide to roll a 48x18, the rear wheel will be set a bit closer.

Dropouts are long in order to make room for different gear combinations (front chainwheel + rear cog). If there were an "optimal" position, then the dropout would be vertical, NOT horizontal.

Your chain fell off because it was too lose.

Quote:
The chain tension on a fixed gear is quite critical, and is regulated by moving the rear axle back and forth in the fork ends. If the chain is too tight, the drive train will bind, perhaps only at one angle of the pedals (chainwheels are not usually perfectly concentric). It should be tight as it can be without binding. If the chain is too loose, it can fall off, which is quite dangerous on a fixed gear.
-- Sheldon Brown

Setting chain tension is one of those things that is much harder to explain via text than it is to actually do in person.



Rear Wheel Sliding:
This is because you aren't tightening the bolt enough and your legs are so awesomely strong that you are pulling the bolted wheel forward. Get a $10 BMX chain tensioner and that will solve that problem...or tighten the bolts tighter.
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Old 06-07-09, 02:35 AM   #15
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OK, here's the best video I could find. It's about motorcycles, but It sort of helps.

NOTE: IGNORE what he says about suspension. Just pay attention to the footage of the TIGHT, BINDING chain and the loose functioning chain. Now, the 1" to 1.25" slack he mentions is appropriate for a motorcycle, but not a bicycle. A bike chain is much, much smaller, so the functional range is also smaller. I run my chain with about .25" (at the tightest section) to .75" of slack.

Pay particular attention to how he checks the chain, moves it along, then checks again. This is because chain tension changes because unfortunately the chainrings, chainring bolt holes, or cogs aren't perfectly round. Higher quality parts (Campy Record, Shimano Dura Ace, FSA) are closer to perfection. But, few are absolutely perfect.

http://www.youtube.com/watch?v=2ljRtU-pjTk

The way to adjust the chain tension in a bike is to move the rear wheel back and forth.

I stand behind the rear wheel, loosen the nuts then place my left hand between the downtube and the rear wheel effectively pushing it back. I then lock the drive-side (right) bolt with the wrench. Check the tension and adjust accordingly. Once it's right, lock the left nut. Then lock them both extra tough to avoid slippage. Then I lock my chain tensioner to keep my wheel from sliding forward during my super awesome sprints.

Last edited by carleton; 06-07-09 at 02:41 AM.
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