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Rear Derailleur HOusing Loops.

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Rear Derailleur HOusing Loops.

Old 06-12-05, 06:19 PM
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Portis
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Rear Derailleur HOusing Loops.

Look at this image from Park tool. How many new bikes do you see with a huge loop on the rear derailleur that is that long? I'm not trying to argue one way or the other, i have just noticed that almost every bike i've seen on the showroom floor has short loops.

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Old 06-12-05, 10:18 PM
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It depends somewhat on the bike and I don't think that they've chosen the best example. Some full suspension mountain bikes shift poorly unless that cable housing loop is on the long side.
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Old 06-12-05, 10:22 PM
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A large loop is better for reduced friction. The "Good housing" photo is a bit extreeme though; the piece of housing that comes with Shimano shifters is not long enough to make a loop that large.
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Old 06-12-05, 11:02 PM
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This is better yet: Avid Rollamajig
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Old 06-13-05, 03:48 AM
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Originally Posted by cheg
This is better yet: Avid Rollamajig
I've used those in the past with great success on Shimano derailleurs. I'm using an Sram 9.0 on my current bike and it doesn't need one.
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Old 06-13-05, 04:34 AM
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thats what i like about the sram derailleurs, it requires a piece of cable 1/3 shorter than hte shimano ones and is almost straight
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Old 06-13-05, 06:35 AM
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Most cheap/poorly assembled bikes will have excessive loops on all the cables. When I performance tune those I end up chopping almost 18 inches of extra housing. Shorter means stiffer, until it gets so short it kinks on the cable. That is one of the reasons for housing stops on frames. Less housing to spring or drag.
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Old 06-13-05, 06:50 AM
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I tend to agree with Sara (our aviation/bicycle mechanic). As for the length of the derailleur loop, it depends on the bicycle. The trailercycle works better with a long loop, but the others I have work better with a loop as short as possible.

I haven't tried the Rooamajig. Anyone has lived through a few winters with it?
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Old 06-13-05, 09:26 AM
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I've not ridden a rollamajig through a winter, but I've been commuting with one for about 200 miles now, often through some pretty hairy weather, and certainly on raods with salt and tons fo crud. It has held up well (*knocks wood*).

I originally thought that it'd end up being a fairly useless gimmick. Not so - the reduction in shifting effort was dramatic.
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