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Old 02-28-14, 12:15 PM   #1
Chesterton
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Spinning rear wheel makes cranks rotate

Hi all, I have a Pashley Roadster Sovereign with a Sturmey-Archer X-RD5(W) 5-speed hub. Recently, I have noticed that spinning the rear wheel by hand caused the cranks to lazily rotate. This is true for both directions. Also, turning the cranks backwards by hand makes the wheel turn as well. Does this suggest a problem with the freewheel equivalent inside the hub itself, or is it possibly due to an overtightened cone? Is it possibly to accidentally overtighten the cone when retightening the axle nuts after tensioning the chain? What should I be looking into first? Thanks for any advice you can offer!
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Old 02-28-14, 12:25 PM   #2
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how tight is the chain? sometimes if the chain is too stretched, the friction will cause what you describe. Has it always done this, or just started? Have you worked on your hub, or removed/reinstalled your rear wheel recently?
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Old 02-28-14, 12:26 PM   #3
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For what you describe to occur there must be sufficient friction present between the wheel and the rear drive component. In an IGH I believe overly tight cones could cause that issue, as the driving components are directly linked to the axle. An overly tight chain could also produce that effect, as well as a hub that has not been properly assembled.
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Old 02-28-14, 12:39 PM   #4
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it just shows that your freewheel in the rear hub has more friction than the friction in the bottom bracket. it's always one way or the other. one could just as easily complain that the pedals (crankarms) don't turn when freewheeling the rear wheel. not that you are a complainer.

that doesn't mean your drivetrain won't benefit from lubrication or adjustment though.
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Old 02-28-14, 01:05 PM   #5
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I don't think it is the chain tension because I just replaced the chain last night and there seems to be quite a bit of play in it. I know I noticed this a few weeks ago, but I'm pretty sure it wasn't always like this.

I have not so far had to remove the rear wheel on this bike in the three years I've owned it but I have repositioned it in the dropouts to tighten the chain from time to time. Is it possible to screw something up by tightening the axle bolts unevenly?

One thing I should have mentioned is that I ride this bike pretty much daily year round, including in the winter salt and slush. The hub is pretty filthy right now. I wiped the sprocket off when I changed the chain but it's really quite grimy behind it still. Can dirt and grime introduce friction there? I would have thought it was sealed well enough to prevent those problems.
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Old 02-28-14, 01:31 PM   #6
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The cranks will walk when the chain is too tight or when the rear bearings have excessive preload - SA hubs need a small >< amount of play to make them operate properly.

Also make sure that the shifting is properly adjusted as if the hub is not completely in gear it could cause this to happen... on older 3 speed a hubs a bike that will "lazily" walk the cranks in 1st will often not do it when the bike is in 2nd or 3rd when the hub is spinning as freely as possible without that little bit of parasitic drag you get in lower gears. Again, these are things that you usually only notice when the bike is up on the stand, when you are riding the weight of your feet on the pedals will negate this.

On an SA 5 speed 3rd gear is the same as second on a three speed as it is essentially a 3 speed with an overdrive and underdrive.

Basically, make tsure the drive is clean and the chain is not too tight, make sure the shifting is adjusted properly, and check the hubs bearing preload... if you have set up QR axles / hubs it should feel like a QR hub before the QR gets clamped down where there should also be a tick of play.
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