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Old 05-16-07, 09:15 AM   #1
Monoborracho
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Low Normal R/D?

I'm thinking of upgrading a touring bike to 9 speed and Jenson has an LX M580 low normal R/D for only $32. I would be using bar end shifters. This means they would both work in the same direction. Anythoughts on low normal for a touring bike?
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Old 05-16-07, 12:40 PM   #2
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It works fine. Having to pull (or twist) in same direction for more "gear" on both sides is more intuitive than conventional setup. It does take a while to unlearn old habits.

It'll drive you nuts if you have more than one bike with different rear derailers.
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Old 05-16-07, 02:55 PM   #3
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Low normal is great because it'll downshift under load easier. This is handy when you're grinding up a hill and need to downshift. I really like it for bar ends--very intuitive. On both sides, up is higher gear, down is lower gear.
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Old 05-16-07, 07:43 PM   #4
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I say buy the derailer- it's a great price and you'll get used to shifting pretty quickly. You'd be looking at maybe a little over $130 for a new 9 speed chain, cassette, derailer and bar end shifters. That's a darn good deal for a very strong drivetrain.
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Old 05-17-07, 07:37 AM   #5
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Quote:
Originally Posted by mycoatl
Low normal is great because it'll downshift under load easier.
I'll have to disagree. On a low normal, you are depending on the spring to pull the derailer onto lower gears while under a lot of torque. The spring isn't that strong. On a high normal (regular) derailer, the cable pulls the derailer on to the lower gears. The cable can put much more force on the derailer for high torque shifts. It's not a huge difference but enough that I don't like the low normal on mountain bikes.

High normal front derailers are entirely different. Those are far superior to the low normal fronts. You can really force shifts to low gears while grinding uphill. No waiting until you've eased off on pedal pressure for the shift to happen.
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Old 05-17-07, 11:23 AM   #6
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+1 to cyccommute
I went with a high normal (LX RD-M570) on my current build for the very reasons he stated.
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Old 05-17-07, 05:21 PM   #7
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Quote:
Originally Posted by cyccommute
I'll have to disagree. On a low normal, you are depending on the spring to pull the derailer onto lower gears while under a lot of torque. The spring isn't that strong.
I'll have to disagree. The chain is not under significant tension at the point where it starts to wrap around the cogs--the point at which the rear derailer does its thing. This is why rear derailers are "better" and fundamentally different than front derailers, which have to move the chain while it's under some tension from the pedals.

I've used both low-normal and regular derailers, and the low-normals have fast and sharp downshifts, while the top normals do a little better at upshifting. The direction in which the shifter has to overcome the constant pressure of the derailer spring is going to be slightly less efficient.

FWIW, though, I think the best reason to choose one or another is to get the levers to move in whatever direction you like.
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Old 05-17-07, 06:33 PM   #8
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Ah, if the low normal derailers don't downshift under stress better than the tradtional ones, why does Shimano make them?

Touring and MT bikes both need better downshifting than better upshifting, hence the low normal derailers.
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Old 05-18-07, 08:09 AM   #9
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Quote:
Originally Posted by tacomee
Ah, if the low normal derailers don't downshift under stress better than the tradtional ones, why does Shimano make them?

Touring and MT bikes both need better downshifting than better upshifting, hence the low normal derailers.
In the mountain bike crowd, RapidRise is commonly referred to as RapidFail. Most everyone I know that has one on a mountain bike is now in the category of 'had' one on the mountain bike...we've swapped them out because the low normal doesn't downshift better. Nothing quite like being in the middle of a steep climb, hitting the button and...nothin'

And come on, Shimano does stuff because they want to sell more stuff. Otherwise we never would have had u-brakes, Biopace, Octalink, different sized axles on different year hubs, RapidRise, RapidFire, 3 (or more) different incompatible cassette systems and about a dozen different chainring patterns. They change things because people have to buy new stuff because the old stuff is impossible to get parts for.
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Old 05-18-07, 07:24 PM   #10
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My RapidRise MTB is humming along fine, thank you. I can't honestly tell you that it downshifts better, because both taditional and RapidRise derailers seem to work fine for me. Professionally, for all the bad press the low nornal systems have gotten, I honestly don't think they die any faster that the old kind. Really, I don't say to start trouble.

I think the whole Rapidrise deal is just another Biopace thing. It's love or hate. I still have bike with Biopace chainrings, BTW.
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